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mailboxTWiM regularly receives listener email with corrections, comments, suggestions for show topics, requests for clarification, and additional information. A selection of these is archived on this page.

TWiM 61 Letters

Nate writes:

Hi my name is Nate. I am a senior in high school aspiring to become a microbiologist. I heard about this podcast through a class I took on biotechnology and have been listening for about 2 months. I really enjoy it and the other two shows even if I don't quite understand everything you talk about, but I grasp most things. So a few weeks ago I attended a biotechnology summer academy for high school students where we study one certain topic for three weeks with a professor at the college it was at. My subject was about the microbes that make up the stromatolites in the Great Salt Lake and why it's important that we understand it. I learned that they are made of Cyanobacteria and certain types of archea. The Cyanobacteria don't really make sense because they don't have a very high salinity tolerance, especially as high as the GSL which is 33% at parts of the lake. But yet they are there. I also learned that the rock is formed by the waste of the microbes which is calcium carbonate. These rocks have the potential to help with global warming. I'm not saying that I agree with the idea of global warming or not, but it is happening a little bit. So that brings up the question, Can we harvest and "grow" these rocks in a lab until they are big enough to put into the wild to "catch" some of the carbon dioxide in the atmosphere? I would like to hear your input on this subject as I didn't have a lot of time at the academy to study it. Thanks

[I asked Hazel Barton, here is her reply]

Actually this is a pretty good question and a number of folks have thought
about microbial CO2 sequestration in just this way.

Many of the carbonate rock deposits (limestone) from about 360+ million
years ago were formed during high periods of CO2, and we believe the CO2
was sequestered as rock by microbial activity. It dropped the atmospheric
CO2 levels and preserved it in a form that is obviously stable over
geologic time scales.

The problem we have today is the ion. To precipitate CO2 as carbonate,
you need a divalent ion. In the ancient oceans, there was plenty of
calcium around, so it was deposited as calcium carbonate (limestone).
Unfortunately, that easy source of calcium has been exhausted, so the
problem comes in generating the ion for the carbonate to precipitate. It
takes quite a bit of energy to do synthetically, so there's no net loss of
greenhouse gases. If someone could come up with a handy ion, generated
from a more passive process (such as decomposition in garbage), then we
could certainly sequester CO2 this way.

A good PhD project!

The stromatolite question is quite a bit more complicated and has to do
with the saturation index of carbonates in seawater when the CO2 levels
drop (from photosynthesis) - I can elaborate on that more if you need, but
the ion is still problematic.


Jim writes:

Hi guys,

This Google Plus community knocks off socks when just skimming through the photos/captions! Don't want anyone to overlook it.

Smithfield, VA

Robert writes:

In TWIM #60 @1:06:23 Michael Schmidt suggests that glucose for fermentation from biomass is a necessary step in production of fuel ethanol. Fuel ethanol and other low molecular weight compounds can also be produced by autotrophic anaerobic fermentation of syngas. Syngas is a mixture of carbon monoxide, carbon dioxide, and hydrogen produced by pyroclastic treatment of a wide variety of organic material including ligno-cellulose, recycled tires, sewage sludge, and natural gas or methane. These reactions have been studied for many years and are being commercialized by Coskata.

Never underestimate the ability of microbes to scrounge a living from nearly any environment with water and energy available.

Jesse writes:

Hello TWiM team! Thank you for the hours of entertainment and education you provide. I have a somewhat morbid question for you that's fairly random--I forget what inspired it exactly--but it has been bugging me: normally when an animal dies, it decays, but what happens if that animal is totally free from all microbes? So, what happens if a germ-free mouse dies in a sterile environment and no one disposes of it for a while? Does it decay somehow, or just dry out maybe?

Thanks again for all you do,

TWiM 60 Letters

Kelly writes:

I’m reeling from this episode!! The symbiosis, the web of life, the energies, chemicals, organisms of
evolutionary progression shaping our world naturally and by human intervention with unknown consequences, then you all tie it to the brain microbiome alterations affecting behavior! Yes!!!
A recent quote from a researcher says soon we’ll call our immune system the bacterial interaction system!
Yes! The microbes rule our world and us. God is bug. Oh the heresy!
This is what we see with inflammation therapy…bugs rule even if you can’t culture them with Koch’s postulates.
I have a Talmudic question:
If most alphaproteobacteria are phototrophic, and the brain doesn’t get sunshine, does vitamin D endocrine system dysregulation have an effect on their population in the brain?

Vitamin D hormone transcribes the AMPs to balance our bugs.
Why we use olmesartan to correct vitamin D dysregulation.
Angiotensin and Systems Thinking: Wrapping Your Mind Around the Big Picture

thank you!!

[the following email was sent to TWiP but I think TWiM listeners will like it]

Joe writes:

Vince and Dickson,

Here is a follow up on your biofuels question. To make fuels from crops succeed we need a biotech breakthrough that I really thought someone would have done already. Basically we need a bug that eats cellulose and converts it back to sugar so you can ferment it. Personally, I think there is a Nobel Prize in it for the group that creates an e. coli strain that converts cellulose to sugars. Once you have that, then you can feed the farm animals the corn and run your tractor on the corn stalks! Or you could use hay or grass clips or wood chips or waste paper, whatever is available cheaply. Until we get that bug, ethanol from corn will just be a niche technology.

People will keep pushing to use corn crops or other high sugar crops to make fuel, but the economics are not good and the lost opportunity costs are too high. Look how the modest current efforts in the USA have pushed up food prices and still required government subsidies to be competitive. No doubt there is a listener out there with lots of arguments for how great ethanol from corn is but I don't see anything like the margin needed to make it a viable market changing crude oil substitute.

I will show my age and tell you that as a senior chemical engineering design project in 1980 at Purdue, we looked at how to convert crop waste materials (like corn stalks) into fuel and it wasn't pretty. The only real way to break down the cellulose was to grind it up and treat it with hot fuming sulfuric acid in big reactors. Fuming sulfuric is 98% concentrated acid that is saturated with sulfur trioxide gas, brute force chemistry for sure! As I remember, you could get pretty good conversion of the cellulose, but the ugly part was separating the good stuff from all the waste acid and the non reactive lignin. Once you got all the acid out of the good stuff, then you still had to ferment the sugars. It is not surprising that you don't see anybody running this process to make fuel! We need a biotech solution to break down the cellulose without all the mess. I think folks were looking at the microbes in termites' stomachs as a place to start., but I have not heard of any progress on this in several years.

I will add that biofuels are not the only option for our fuel supply. For the past 100 years, we have had repeated dramatic reports that we are about to run out of oil and yet it never seems to happen! I remember a particularly detailed one in Scientific American about 10-15 years ago with beautiful graphs and everything. Each time the trumpets of doom sound, some smart engineer or geologist comes up with a new way to extract more oil. I don't see any reason why this trend will suddenly stop this time, we still have lots of tar sands, deep oil, and shale oil that have not been touched. Please note that I am not expressing a political view on the social correctness of these options just the technical aspects. Even more impressive are the reported quantities of frozen methane hydrate clathrates on the ocean floor that would likely be fairly easy to extract. Some estimates are that there is more than 10 times the amount of energy stored there than in all the oil we have ever used. Obviously none of these fossil fuels address the CO2 generation concerns that many people have.

Wind, solar, hydro and even nuclear power all have their places and I hope their niches keep growing as the technology improves, but nothing comes close to competing with chemical energy as a cheap, portable, high density source of energy. One just needs to look at biology to see the truth of this; plants fix the suns energy into chemical forms that then cascade through the food chain ever evolving into more complex forms. How cool is that!

Thanks for helping me stretch my brain each week! Thus ends "This Week in Chemical Engineering"!

Warmest Regards,

Joe Griebstein
EH&S Manager, LSG

Robin writes:

How about phage fossils?

Now that we know that phages have an apparently symbiotic relationship with mammals, is it too farfetched to imagine that some phages were once incorporated into - and expressed - in metazoa?

One line of research might be a search for such fossil sequences in the genomic databases that already exist. Perhaps someone is already doing it?

The reference to salicylates in my last email was prompted by Dr. Schacter's comment that methyl salicylate reminded him of acetylsalicylic acid, and to show how the acetyl group was important in the clinical effects of the latter.

Thanks for such thought-provoking and paradigm-shifting discussions!

TWiM 59 Letters

Oscar writes:

This is the greatest TWiM ever. (#58)

I've always been interested in evolutionary complexity and for the last seven years or so I've been unable to think of evolution in terms of traditional survival of the fittest on an individual level--at first it just seemed too simple. But through these years of rumination on the subject often provoked by a science story in the news (or on a science-ey show (radio-lab, I'm looking at you--I love you but I'm looking at you)) that approaches evolution through the perspective of survivability of the individual as opposed to survivability of a complex ecosystem of interactive life-ey things and then failing to see obvious conclusions because of this narrow view, I'm nearly unable to conceive of the idea of an 'individual' organism having any meaningful impact on (even short term) evolution.

This episode of TWiM starts with Elio giving a very masterful explanation of the paper: Underground Mycelial Networks Carry Warning Signals to Plants. His gentle and thorough description makes me long for an opportunity to attend a lecture class with him. He is truly a masterful lecturer with managed digressions that are interesting and make it clear that he is processing the information further as he speaks making the reality of hearing a brain (or brain-biome) at the top of its performance and with such great depth of knowledge really tangible and exciting.

Of course the content of that paper is also remarkable and Vincent and Michael do spectacular jobs of interjecting and referring to relevant information as well as questioning things where it's due. The dynamic in this episode is really great.

Then to top it off the second paper about the Brain Microbiome is as amazing as the first paper. During the discussion of this paper one can really feel the excitement and disbelief from the trio as they consider the implications of how this can change our understanding of the brain. I'd like to add that I wasn't at all surprised by the fact that our brain has it's own microbiome (I actually was a little surprised that it wasn't a foregone conclusion).

This episode was truly enlightening and highly entertaining. I was so riveted to the entire thing--I felt like that's what witnessing the moon-landing for the first time must have been like--it's real discovery and really cool.

So thanks TWiM guys and keep up the work. I don't care if you don't produce an episode every week, just get them out occasionally because this is important stuff that people need to know.

Finally: I'd just like to throw this out there: I'm at the point now where when I seriously think of how things evolve, all pieces of a system have to be taken into an account. It's easiest for me to grok if I consider a physical space and all of the life and non-life inside it and then also to consider a significant time-period that must include thousands if not millions of generations of changes and co-dependencies that have developed and curated. I know life has evolved to evolve (I can give a number of examples of that) and I know life has evolved to evolve to evolve (I even have a couple of that) the next level isn't easy to see but I guarantee it's there and it probably recurrses an innumerable amount of times in ways that are both simple and complex and we just have yet to understand.

I'll leave you with this: Despite the appearance of randomness guiding the evolution of the beaks on Darwin's finches I promise that the beaks of those finches have evolved to have high-rates of randomization and likely even environmental influences that either magnify or reduce the amount of randomness that's displayed--after all, evolving a trait that helps them evolve will increase survivability and that's the meaning of life.

Thanks for the great TWiM!

Oscar Prill
Technology Director
Lionsgate Academy

Mark writes:

Hi Vincent et al
I have been listening to TWiM for several weeks after moving to a new job that requires me to undertake a one-hour drive to work. I enjoy the show very much: in fact, I enjoy it so much that I am thinking of setting up a similar podcast this side of the Atlantic.

But this is not the reason I am writing.

I listened to your discussion of the brain microbiome this week. And, even though I note the question mark in your title after the term "brain microbiome", I think you were not skeptical enough.

OK, I admit that the paper presents an internally consistent story. But they don't report trying to grow the bacteria. And, rather than one organism, they would have us believe there is a kitchen sink's worth of microbes in these brains. Remember when we look at most sterile samples, we assume that a mixed growth equals contamination! And alpha-proteobacteria are common contaminants of water supplies, even in the International Space Station!

But more generally, as Carl Sagan put it, extraordinary claims require extraordinary evidence! And IMHO the evidence presented here is not compelling enough to overturn over a century of microbiology and histopathology. If these bacteria are really there, would we not have seen them already? If we look at precedents, we could be looking at the next Helicobacter pylori and these authors are going to be Nobel laureates. But I think a more plausible precedent is XMRV or arsenic life, both of which turned out to be nonsense. Go take a look at Ioniddis' paper "Why most published research findings are false"

Only time and attempts at independent replication will tell what is going on here. But I am prepared to wager that in ten years time this paper will have been discredited or forgotten.

Keep up the good work!


Professor Mark Pallen
Professor of Microbial Genomics and
Head of the Division of Microbiology and Infection
Warwick Medical School
University of Warwick

Robin writes:

TWiM #58: The brain microbiome

The brain microbiome would have been outright heresy in the latter 1960s when I had medical microbiology in med school. Today's facts are stranger than the wildest imaginable fiction of a bygone era.

Both papers go to show the enormously complex interconnectedness of all things.

The idea of signals transmitted through a network of mycorrhiza suggests a slow intelligence with signals acting over hours or days instead of milliseconds as is the case with neurones. An awareness associated with such an intelligence would have little commonality with what is familiar to us. Even though chemical inputs equivalent to smell and taste, mechanical inputs equivalent to hearing and touch, and light inputs equivalent to vision could affect such a system, they would be so different that it may be impossible to form a concept of such awareness.

It is to be noted that in Eastern traditions, awareness is consciousness with content; appropriately organised complex configurations of matter and energy will manifest awareness just as non-magnetic pieces of iron in a magnetic field will manifest magnetism.

Methyl salicylate is present in large quantities in oil of wintergreen: even a teaspoon if ingested can cause severe salicylate toxicity. Aspirin is acetylsalicylic acid. It is less irritating and less toxic than methyl salicylate. The intrinsic stickiness of blood platelets depends on platelet cyclooxygenase, which is inactivated by acetylation by acetylsalicylic acid. A single tablet of aspirin will inactivate the platelet cyclooxygenase in all the platelets. It also affects the other blood cells, but unlike platelets, they regenerate their cyclooxygenase. Platelets have to be replaced by newly formed platelets. Since platelets have a lifespan of seven days, a tablet of aspirin is good for two to three days.

Eli writes:

Hi Vincent et al!

I was listening to the TWIM episode #55: In the copper room, about bringing down hospital infections.

You mentioned two things as being the main problem. The first one was high occupancy rate.

Quote from the episode:

"The second and this is probably the most important reason, is that you can't tell that things are dirty - from a microbial perspective. And we don't routinely survey the area to ask what is the microbial load"

I am thinking, what if the bacterias could somehow be made visible. It would be real cool if material could be engineered to change color to show if there is a high level of bacterias and other pathogens, to alert that a surface needs to be cleaned. It doesn't necessarily need to be visible to the naked eye, but just if some special lights got shined on it. I have no idea if it will be possible, I just liked the thought.

As you say, the main problem about hospital infections, is that the problem is invisible. And if things are invisible to our eyes, it is harder to shine mental light on it, because we don't directly get reminded about it on a daily basis. Hereby my wish for "bug luminol" is passed on.

Joe writes:

Hi guys

I really enjoyed the discussion of PULs on the most recent episode of TWIM. I had a minor correction with respect to the discussion of the connection between diet and IBD. During the discussion, one of you talked about a progression from ulcerative colitis to Crohn’s disease. In fact – these diseases, although categorized as inflammatory bowel diseases, have fairly different (albeit poorly understood) etiologies. UC is generally restricted to the colon while CD can be localized anywhere between the mouth and anus. Also, IBD patients generally have one or the other – but not both. They don’t really progress from one to the other in any individual patient.

Keep up the great discussions of the wonderful world of bacteria and human health.


Joseph McPhee Ph.D.
Michael G. DeGroote Post-Doctoral Fellow
Coombes Laboratory
McMaster University, Department of Biochemistry and Biomedical Sciences

Dave writes:

Most interesting talks on copper in disease transmission reduction environments. How about silver?

I possess several pairs of army socks (literally), a percentage of the fibers (3%? 12%?) woven into which are microcoated (or embedded, or something) with silver. The purpose is suppression of undesirable (potentially mission-defeating) microbes.

I believe they are effective. I believe there is some literature on the efficacy of silver, and rationale for its selection over copper. I think I've seen some ventures at explaining the mechanism, but I don't have the stuff in my head and can't go looking. Worth observing that they seem to enable wearing socks for more than one day without getting stinky.

Interesting aside: I went looking for army socks after hearing an ER doc describe managing the pain of 36 hours on his feet by wearing wool army socks. His belief was that the wool provided a sufficient secondary cushion to dampen the impact of walking all day on concrete floors (which have no give, relative to asphalt or whatever). My feet have plagued me with easily acquired aching, so I went looking. The socks, combined with placebo action, seemed to provide noteworthy reduction of discomfort. As to heat objections, which seem culturally common among us, he reported year-round use without problem. I found them entirely comfortable, probably downright insulating, when worn in Fresno summers under boots, and certainly no worse than conventional or lightweight socks, so I ratify his year-round prescription, since they're pleasantly warm in winter too. (pause for breath) Not itchy either, in this formulation, to the contrary of old complaints about wool.

Anyway, recently I went to the military/police gear store for more socks. I was disappointed not to find the familiar thick wool, but did decide to try the new blends. Some were thinner wool blends, and others blend cotton with synthetics such as lycra, I guess. I sprung for some, and was so pleased with the (quite inexpensive, relative to Walmart work socks) performance of the silver blended ones that I went back for more. This model is near knee-high, so has the benefits (for those to whom it matters) of compression as well, potentially reducing edema and whatnot.

Anyway, whatever. Much enjoy the show(s), encountered on internet radio Science360 (which you might mention sometime). Hope you find the bit on silver vs. copper interesting. Maybe it suggests a further look along the table of elements.


Tim writes:

Michael Schmidt's enthusiasm and passion for all science is always wonderful to listen to. Hearing him discuss his own work was even more of a treat. Congrats to him and his collaborators on their great work telling a fantastic and relevant story!

- Tim

Bernadeta writes:

Dear TwiM podcasters,

Thanks for another great episode! Each TwiM/P/V episode you do brings me so much inspiration and I wait impatiently for another one to come. Usually, though after each episode I have more questions than answers, which I think is great because that what science is based on, like Feynman said: science is expanding frontier of ignorance the more we know the more there is to answer.

Regarding the last episode, I always find these phage-bacteria arms races very fascinating; they are a perfect example of how evolution can work in short period of time.

On last episode it was mentioned that CRISPR/Cas system takes up DNA randomly irrespectively of whether that would come from a "helpful" or a "bad" phage. If the process is random then would it also take up DNA that was acquired through transformation or transduction?

Can Cas somehow distinguish if it's a phage DNA or not?
Is it maybe specific for some kind of base modification like hydroxymethylcytosine that are found often in phage DNA, or does DNA sequence has to be of certain size, or maybe the DNA has to be either linear or circular (but if circular then why the phage induced resistance islands do not get accidentally incorporated into the CRISPR locus)?

Can one do a BLAST search to find if the spacer sequences in CRISPR locus are exclusively from phages or sequences from other sources are also present? I know that it would probably be of no use to incorporate random sequences into the system but then I presume that there has to be a mechanisms for distinguishing where the DNA comes from?


Andy Camilli writes:

As far as we know, the capture system is random. The phage CRISPR/Cas even occasionally captures a piece of its own genome, which is a big mistake, because it will then degrade its own DNA! What we find in these instances, is that points mutations have arisen, either in the spacer or in the target in the phage genome, that abrogate hybridization of the crRNA and thus degradation is prevented. Presumably, these mutations are selected for rather quickly.

-Dr. Camilli

Charlotte writes:

Re: ASM Discussion - I wonder how much journal's biases against publishing negative results contributes to misconduct.

Peter writes:

Hi TWiM team
I hope you were able to see the Google tribute to Julius Richard Petri:

Not sure about the streaking technique shown in the doodle though.

Jim writes:

Dr R:

This is old on uTube, but new to me. Can I suggest it as a listener's pick. Surely a similar dance be created from all the fields your podcasts represent!

I heard about the dance from class 129 by Dr. Gerald Cizadlo. His engaging manner is somewhat like yours and just this year he began offering an online version of this class, Bio 3020.


Smithfield, VA

Jim writes:

Hi Y'all,

Dr Schmidt, on TWIM 35, after the 2012 ASM conference, you mentioned use of the Quartzy networking cards at many poster sessions. Did you see the cards used this year, were they more prevalent (3,300 used last year), and were poster sessions as plentiful as last year? Have the cards stimulated any competitors?


Jim Vandiver
Smithfield, VA

PS: TWIM 56 at the ASM was awesome, just awesome! It's like listening in on a discussion between Einstein, Edison and Feynman.

Peter writes:

Dear TWiM team
I see that the Oregon Senate approved a bill establishing brewer's yeast, Saccharomyces cerevisiae as Oregon's official state microbe.

I can understand the popularity of brewers yeast, what other microbes do you think could be chosen as official state microbes?

I think food and drink related microbes would be favoured by most people so various species of Lactobacillus may be popular.

On that subject I see that there is a paper on microbiological profiles of ŞALGAM, the Turkish lactic acid fermented turnip and black carrot drink:

It is a popular drink in Turkey but rather an acquired taste for those unfamiliar with it.


Jacob writes:

Hi all,
My Dad sent me this article after I sent him a link to your episode on biospeleology.
It's about biofilm sheets in underwater caves under the Australian desert that glitter in the torchlight due to calcite crystals that are formed in the biofilm.

Jim writes:


Here's a link to a Maker site that discusses how to do a 3D print of your brain.

Smithfield, VA

TWiM 58 Letters

Daniel writes:

Dear Vincent and his fellow TWIMsters,

Hello, my name is Daniel, I am a first year graduate student at Michigan State. I would like to thank you all for making a great podcast. I recently caught up to the most current episodes by having my own TWIM marathon during my 6 hour drive home to Wisconsin over the holiday break.

I'm not sure where to begin explaining how much I value this podcast. As someone who cares for outreach, education, research and in general having a good time with science, you folks are first rate. This series has been accessible all the way through for grandparents to grad students. When things maybe get a little to verbose you have done well to bring it back down. But you also make it just intriguing enough to hold the attention of the grad student in me. I have even been known to actually follow along in the articles. :) And of course I have had a great time learning and exercising my mind while listening in. You guys went even further to impress me with the discussion of Jo Handelsman's research last time, it gave me lots to think about for the future. Please keep up the great show!

I also wanted to share a paper with you all that I thought about after listening to TWIM #47: Resistance On the Surface. Michael said something that made me remember it during his discussion of the paper in reguard to conjugation. He said, "It's having sex wicked fast!", and you guys went on to exclaim about how fast conjugation was happening.

In this Science paper by Babic et al. in 2008 they are using a very beautifully designed experiment to visualize DNA transfer by conjugation, and it agrees... wicked fast! I suggest the supplemental videos. The experiment involves a recipient strain that is Dam- or defective for DNA methylation by Dam methylase, and which has a SecA-YFP fusion . (Note by MGS--- it is not is SeqA ) SecA being (correct me if I'm wrong) the protein that keeps replication from occurring when hemi-methylated DNA is present in the cell. Effectively keeping multiple rounds of replication from occurring at once since newly replicated DNA has not yet had the time to be methylated on the new strand.

The result of this recipient cell is no DNA methylation, or SecA-YFP binding and diffuse fluorescence. The donor cell, however, has Dam methylase and will donate methylated DNA during conjugation. When this happens, the donor DNA will become hemi-methylated upon replication allowing SecA-YFP to bind and show a localized fluorescence to that DNA. This means we can watch it happen at a single cell level! They do show a rather surprisingly fast transfer of DNA, as well as make other neat conclusions in the paper which include the use of a red fluorescent gene on the donor DNA to measure expression of conjugated DNA, but the e-mail is long enough already. It's not a bad read, and I hope my explanation was TWIMable enough.

Thank you for providing a wonderful supplement to my microbiology education, and Happy New Year,


Here is the link to the article.

Robert writes:

I am listening to eps 49 and heard the mention of biodynamic vineyards. Biodynamic farming is similar to organic farming, with the addition of such things as burying dung in the horn of a bull and sprinkling magical powders around the farm. Take a look, it's quite entertaining total nonsense.

Clark writes: [this email was read on TWiM #56 but not published]

I'm slowly getting caught up with TWIM after Christmas and just listened to episode 43. I came away very confused and I hope you can clarify something for me.

I understood that the major problem with using phages for disease was due to FDA regulation. However when speaking about acne you suggested that there were ways for the FDA to approve them as a type of drug treatment. If this is the case, then why on earth aren't they being used to treat anti-biotic resistant TB or other such diseases?

If you could do a show on the interplay between the FDA, government regulation and commercial use of phages to control disease I'd be quite excited. I confess I get confused when hearing about the problem of antibiotic resistance on the one hand and phages on the other.

Todd writes:

it's true

(also, I love your podcast, and in the future when I write a longer letter I'll explain more why I love the podcast)

Erik writes:

Long time listener, 2nd time emailer. ID doc. Mostly i treat HIV patients and hospital acquired infections. You've talked a lot about copper as an antimicrobial and that ancient civilizations might have used it to reduce war wound infections. I'm not aware of it's use in modern wound care. However silver based products are used a lot in wound care and on catheters, etc. I would be interested in understanding the antimicrobial properties of silver, and in why copper is not used topically if it is so effective at killing bacteria. Thanks.

Jim writes:

Hi all,
Thought Michael Schmidt might like this reference. It is to a Canadian podcast called Quirks and Quarks.
The reference is:

In this episode, they discuss a paper by Jayne Danska talking about diabetes in nonobese mice. The outcome of diabetes can be changed by changing the microbiome in young mice. It reminded me of Michael' s thinking on how the microbiome might come into play in the future.
I found it very interesting after hearing the TWIM episode.

The paper appeared in Science.

Best Wishes,

Justin writes:
Hello to the TWIM team and guest(s) I have written to TWIV but this is my first letter to TWIM. I was recently watching a documentary about
how beer was the driving force behind beginning agriculture and numerous other massive human accomplishments and the documentary
mentioned skeletons from 500 BCE containing tetracycline. My first reaction to this was where is my computer I have to find this article.
Well I did find that the orgiginal discovery in the late 1980's was meant with extreme skeptacism (not surprisingly) but then I also found
an article from 2010 with more data to back up the claim. Now, I am not one to interpret Mass Spec data very well but would love to hear
what the TWIM team thinks of this. Here is a link I found to the article in the American Journal of Physical Anthropology

Thanks to all for the wonderful podcast,


Robin writes:
Alaric the Great

One would expect that Italians would be familiar with Alaric the Great.

Alaric I (Gothic: Alareiks; 370 – 410) was the King of the Visigoths from 395–410. Alaric is most famous for his sack of Rome in 410, which marked a decisive event in the decline of the Roman Empire.

TWiM 57 Letters

Wink writes:

Great HAI work! I'm not through it yet. I want to question, though, whether fomites are really important in influenza transmission. I don't think so.
Wink Weinberg (ID)

[flu can transmit by fomites in guinea pigs: ]

Bernadeta writes:

I'm a second year microbiology undergraduate and I very much enjoy all of your podcasts; they are a great pleasure to listen and I wait for the new ones every week.

Since the last episode was all about copper I would thought it would be appropriate to point out this paper published in Nature in 1984- "Why whip egg whites in copper bowls?".
Who would have thought that a paper about copper bowls and cooking could've been published in Nature :)

I also think that this paper could be shortly discussed one one of the podcast: traditional mutational study but seems quite perspective- what do you think?
"Identification of Salmonella Pathogenicity Island-2 Type III Secretion System Effectors Involved in Intramacrophage Replication of S. enterica Serovar Typhimurium: Implications for Rational Vaccine Design"

Thanks again for your podcasts and keep them coming!
Kind regards,

Frank writes:

Bravo Michael!

I formerly developed a oxygen radical (not ozone) surgical instrument sterilizer so have dealt with the difficulties of disinfection and HSAs. Successfully sold to Stryker Instruments.

You mention the problem of economically obtaining copper hardware due to the pervasive use of plastic. If you think about our common household plumbing fixtures, it is clear that plastic can be plated with many metals and shipped around the world by air.

Plastic plumbing fixtures are typically plated with electroless copper followed by nickel then chromium. Air shipment is not an issue so your former plating vendor simply did not have the technique/knowledge to give you a sturdy uncontaminated injection molded part. I was involved on the development of many of these processes in the 70s. Rhom & Haas is still a major supplier of plating solutions and methods.

Similarly, any metal part can be easily plated in whole or in part with copper or copper alloys by the OEM. A quick swipe with ammonia will remove finger oils which could allow bacterial film growth and will expose fresh copper surface.

Despite all this antimicrobial furor, I look forward to the "omic" studies identifying how many HSAs are from the environment vs. the patient. Microbiome studies seem to be showing that microbial diversity balance rather than eradication is often the key mechanism of maintaining health.

Thanks to all you TWIV, TWIP & TWIMmers for creating and maintaining one of the most educational, accessible and plain old FUN scientific forums ever!

Best Regards,


Jim writes:

I was amazed to see note 13 in the caption for this article out of Apr/May 2013 AARP magazine about use of copper alloys on frequently touched surfaces. Copy of that page attached as a PDF.

Smithfield, VA

He sent

Lori writes:

I love your show, especially the recent episode about the use of copper in hospitals.

I am a nursing student at University of Nevada, Las Vegas and I am always cleaning patient bed rails and call lights. Patient hands are not the only thing that comes in contact with bed rails. The rail is also frequently used by nurses to temporarily hang pieces of tape while inserting an IV or changing a dressing. The tape, with all its germs attached, is removed from the bed rail and taped onto the patient's skin in close proximity to an open wound.

A future study might include the pathogens transmitted by stethescopes. People are pretty good about washing their hands, but I never see anyone cleaning their stethescope. It is my very unscientific, empiric observation that the stethescope is one of the biggest fomites in any hospital. I have seen copper writing pens for sale, but I am not aware of anyone who makes a copper coated stethescope.

Another possible fomite is employee badges, they come in contact with our patients when we lean over them (I stuff mine in my pocket so it does not contact the patient.)

TWiM 55 Letters

Jennie writes:

Hello TWIM friends!

Jennie here - a long time fan of TWIV, then TWIP and of course happily learning from your great TWIM podcasts.

Thanks to Michael Schmidt's fascinating discussions - including those regarding copper and microbes - which have really got me thinking. (Copper's natural anti-microbial activity can lower nosocomial infections by decreasing pathogens on hospital surfaces. To plagiarize Mr. Schmidt's own site at the Department of Microbiology and Immunology at the Medical University of South Carolina: "The 4th leading cause of death in the United States, behind heart disease, cancer and stroke, is Hospital Acquired Infections (HAI) where approximately five percent of the patients admitted to US hospitals will acquire an infection.  Very little is known of what fraction of these infections result from a microbial contribution obtained from objects present in the built environment."

It appears that copper does have a contribution to make - and I can imagine that there will be some formidable costs in changing surfaces from plastic & alloy & steel to copper.

To decrease costs of switching to copper surfaces for commonly touched fomites (microbe carrying objects) like IV poles and steel hospital infant bassinet units - you're talking to an OB nurse here - I began to think about a 6th or 7th grade experiment we did in school when I was a youngster with copper plating.

With that in mind - I did a quick search for a video on copper plating on Youtube and found this video - which just gives you a peek at how easy it can be to copper plate existing metal surfaces. I'm wondering if this could potentially be a cost saving application for some institutions. Will it be necessary for institutions to re-purchase when perhaps they could resurface?

Of course, I hope that you realize how very much your team has done and is doing to increase our understanding of the tiny denizens without and within us. What an adventure!

Special thanks to you Vincent for sparking greater excitement and transparency in science. Thanks to Jo Handelsman - soil microbes are so vital and so unknown - thanks for the recent apple orchard soil discussion and for her deeply appreciated advocacy for women - Yay! Of course Elio Schecter and Stanley Maloy - fantastic!

Yours with warmest regards

Jennie BSN RN

“In the world through which I travel, I am endlessly creating myself.”

Frantz Fanon

TWiM 54 Letters

Jacob writes:

Hi all,

Saw this media release from the Australian Institute of Marine Science about researchers isolating a combination of probiotic bacteria to assist in the prevention of Vibrio infections of spiny lobsters in aquaculture and thought of TWiM.

Keep up the good work,

12 December 2012
Winning combination of bacteria found to combat deadly marine pathogen
Research conducted at the Australian Institute of Marine Science (AIMS) has delivered promising results in combating Vibrio owensii - a bacterium that is responsible for mass mortalities of cultured ornate spiny lobster larvae.
The high commercial value of the ornate spiny lobster (Panulirus ornatus) means it has the potential to be an important product of the Australian aquaculture industry. However, nutritional deficits and bacterial disease during the long larval phase of the species makes captive rearing difficult.
Scientists from AIMS and the University of New England (UNE) have been able to isolate a large number of bacterial cultures – or probiotic candidates – from wild lobster larvae and their natural prey items, and from the lobster aquaculture system at AIMS in Townsville. After successive tests, they found that a combination of two probiotic bacteria, referred to as PP05 and PP107, provided the most effective protection against the pathogen Vibrio owensii, enhancing survival of the larvae by as much as 80 per cent.
AIMS Research Scientist, Dr Lone Høj, who led the project, said “Our work has uncovered a winning combination of “good” bacteria that appear to dramatically improve larval survival. In a further study we looked at how and why these two bacteria were so effective when working together against Vibrio owensii.”
UNE PhD student Evan Goulden said “This research highlights the value of identifying biocontrol agents that are able to intercept the infection cycle of a serious aquaculture pathogen, as such the study represents a milestone in proving the value of using probiotic mixes to prevent microbial diseases.”
“Disease management is critical in food production systems and this is particularly true for seafood produced in aquaculture systems. The development of alternatives to the antibiotics currently used in such systems is becoming a national priority in countries around the world” says AIMS Principal Research Scientist, Dr Mike Hall.
‘Identification of an Antagonistic Probiotic Combination Protecting Ornate Spiny Lobster (Panulirus ornatus) Larvae against Vibrio owensii Infection’ is published in PLOS One:
‘Probiont niche specialization contributes to additive protection against Vibrio owensii in spiny lobster larvae’ is published in Environmental Microbiology Reports:
The authors are Evan Goulden (AIMS/UNE), Mike Hall (AIMS), Lily Pereg (UNE), Brett Baillie (AIMS), and Lone Høj (AIMS).
Media contacts:
Dr Lone Høj, Research Scientist, (07) 4753 4364; 0408 716 094; This email address is being protected from spambots. You need JavaScript enabled to view it.
Dr Evan Goulden, Research Assistant, University of New England,0439 446 204, This email address is being protected from spambots. You need JavaScript enabled to view it.
Dr Lily Pereg, Senior Lecturer, University of New England, (02) 67732708, 0427063057, This email address is being protected from spambots. You need JavaScript enabled to view it.
Wendy Ellery, AIMS Media Liaison, (07) 4753 4409, 0418 729 265, This email address is being protected from spambots. You need JavaScript enabled to view it.

Trudy writes:

Dear TWiM team,

Since the topic of patent law came up on episode 48 I wanted to add my two cents. Six months ago, I switched to a career in patent law after 12 years as a bench Virologist. I have found this job to be very challenging and rewarding, and I'm currently experiencing a rather steep learning curve. However, the reason I'm writing is because I did want to mention that one does not have to be a lawyer, or even plan to go to law school to practice patent law. Many firms are willing to hire PhDs with no prior experience in patent law as science advisors or patent agents and train them on the job. The reason they're willing to do that, is because of their extensive background in science, which is imperative in this particular legal field. In our firm, all of our six science advisors have PhDs, and three of our five attorneys do as well. Although learning the law is pretty difficult, in my opinion, it is much easier to learn the law on the job than it would be to learn the science, and I have tremendous respect for the two attorneys in our firm who do telephone directory ireland reverse phone lookup not have PhDs, because they seem to be so well versed in the science as well. I recently asked one of our partners (who has a PhD) how much of what he learned in law school he has actually applied to this particular job, and he said “zero”! On the other hand, attorneys do make a lot more money, and there are certain things that they can do that a patent agent can't do, but my point is that a PhD is more than enough to have a rewarding career in patent law. Personally, I have absolutely no desire to go to law school!

Thanks again for continuing to provide so many different stimulating and thought-provoking topics.

Kind Regards,

Jim writes:

Esteemed Sages:

Post-Sandy seems an appropriate time for a TWIM devoted to mold since the storm generated many opportunities to deal with it? I'm also battling it in my ventilation ducts to the extent that we replaced all the supply lines beneath the house and some of the returns in the attic, and installed an electrostatic filter upstream from a HEPA-type filter, plus a UV light by the heating/cooling coils. Over the years I've inspected the ductwork for integrity and cleanliness and just didn't think we had conditions that allowed mold growth until we found 7 of 23 supply lines each of which that looked inside like they were spray-painted with black primer over a good many feet. Meanwhile outside we've been unable to prevent black mildew from growing in playing-card patches on treated wood coated with mildewicide-infused stain and exposed to sunlight about eight hours a day.

I bought five mold collection kits containing petri dishes and growth medium just before detecting the seven register lines. At first they seemed a good idea to apply now and perhaps in the spring or summer, but then I found this site with considerable mold information that seems reputable. My interpretation of what the site says is that conditions and materials contributing to mold must be removed to fix problem. While removing bad ductwork helps I don't think it corrects the condition problem(s). The site says sprays and chemicals don't work! And sampling with my kits followed by lab work to identify mold types won't tell if harmful mold is at levels requiring action. In addition, unless you use laboratory grade filtration, it won't reduce the presence of mold to livable levels, and UV radiation is only good directly under the light, not particulates flying by. Electrostatic filters apparently only remove a small amount of mold-related material as do good filters, but not all and probably not enough for sensitive people, plus they work best if the ventilation fan runs continuously. Much harmful mold material is too heavy to get sucked into any ventilation system, anyway, and is only removed by vacuuming often, mopping and washing fabrics. Finally, only an expensive, trained environmental specialist can do a good evaluation, prescribe corrective action and determine if that action has been effective. This site shows we have just one such specialist in my state,Virginia, about 300 miles away.

Do you folks agree our best approach would be to napalm the house and replace it with a stainless steel cube, or wear environmental protection suits, or move to who-knows-where....? Of course the guys doing all the ventilation work used no respiration protection, but then they were all in their 20's and 30's versus our 70's.

So what's going on with mold nowadays, anyway? Is there more of it? I've no problem understanding why you need to remove wet and moldy plasterboard and carpeting, but have seen home shows where mildew-stained woodwork behind the wallboard is sprayed with something which they implied would fix the problem. You're the only really reliable source of complete and competent knowledge on the topic, so many of your listeners should appreciate your comments.


Smithfield, VA

Don writes:

When do we get to hear the results of Michael's experiments and interventions with copper and microbes?. The suspense is killing me, or did I miss it? Please continue your marvelous podcasts.

TWiM 49 Letters

Robin writes:

The matriarch of a hunter-gatherer band might prefer males to be assigned to specialised training in hunting skills. So the subconscious bias probably goes back a couple of million years to the early days of Homo before sapiens.

Chip writes:

Saw this paper in my inbox this morning and thought It might be a good fun discussion paper on an upcoming TWiM episode!


Meimei writes:

Dear Dr Racaniello,

I do not have the talent for a M.D-Ph.D. at Columbia, but I am madonna pokies definitely a huge fan:)

It's striking how and where the interaction of antibody and bacterium occurs (TWIM #48)! Learned a lot from listening to your interpretation of the paper. Many Thanks!
Just have a question about one antibody and one bacterium. Is it commonly considered more than one antibody molecule per bacterium?

Many Thanks, again!

P.S. Can this finding extent to the interaction between virus (e.g. HIV) and neutralizing antibody? It might be we just look at the wrong place for all those years!

TWiM 48 Letters

Sierra writes:

Hello Racaniello et al.,

I am a plant pathologist for a vegetable seed company in Washington state.  I listen to TWIM, TWIP and TWIV podcast while I read extensive disease resistance screens.  I started out studying microbiology as an undergrad and discovered plant pathology that allows me to study microbes and plants together.  Listening to these podcasts keeps my mind engaged while looking at thousands of potentially disease baby plants.  I really appreciate what you all do to put together such intellectually stimulating topics.

If I may suggest a topic as well.  Iron sequestration and uptake in bacteria is very fascinating and affects many aspects of bacterial life.  I may be biased as I worked on iron uptake during my Ph.D. I have listened to many of the TWIM podcasts and iron pops up in discussion now and then.  It would be nice to listen to a discussion of this topic from your perspective.

Keep up the good work,


Eric writes:

Dear Twim:

Episode 2 had a career inquiry from a listener.  The listener was considering additional graduate work Pokies, but was not sure which way to go or whether to invest the required time and energy in an MBA or Ph.D.

May I suggest intellectual property as a career path?  Most patent attorneys are former "lab rats."  Patent attorneys enjoy a good salary and interaction with some very intelligent and interesting people.  Though considerable work is required, intellectual property can be a very rewarding career.

Best regards,


Patent Attorney

Flagstaff, AZ

Ori writes:

Hello all!!

Quick follow-up from Twim 47. 

It seems that many bacteria have means to take up foreign DNA and integrate it Into their own chromosomes. This definitely can provide a selective advantage depending on the nucleic acids being taken up. On the other hand, transferring your own DNA to another cell seems to be quite unselfish. For example, if I had some form of an antibiotic resistance gene, why would I give it away to others that would, in the end, compete with me for nutrients? In essence, what is the selective advantage for giving away nucleic acids?

Thanks a lot and have a happy holiday!

TWiM 47 Letters

Maureen writes:

I love all your series (TWIM,TWIV, and TWIP) and learn immensely from them. I am a Clinical Research Nurse and work at NIH in the National Institute of Allergy and Infectious Disease (NIAID) unit that houses the KPCR  patients that you may have recently read about.

I'd like to hear a discussion about this isolate as you educate everyone so thoroughly. Our hospital has worked diligently to track and eliminate this organism from our hospital and we've just about succeeded but I'd still like to be better informed about KPCR. Thanks.

P.S. Please Please Please start a TWIB!! We work with so much that I still need to be educated about various bacteria.

Thanks immensely for all the education you give us.

Jim writes:

Hi Vincent and Friends,

Thank you very much for the informative and often imaginative discussions that take place in TWiM. It's a real pleasure to listen to such a quality, fun, easily accessible (and free!) source of microbial material. I'm sure you are often thanked for taking the effort to put it out there, but I wanted to add my voice. As a cell and molecular biology student it offers some wonderful connections and points of interest to my education.

My question relates to a recently published book by Trudy M. Wassenaar that I have been reading, titled "Bacteria: The Benign, the Bad, and the Beautiful." Has anyone read this book, and if so what are their thoughts on it? I would recommend it to those with a broad interest, or who need an introduction, like students such Pokies as myself. It offers an incredibly interesting and diverse description of bacteria and is easy to understand. I actually picked it up because it was recommended by the google+ "Microbiology" account (

Thanks again, and warm regards.

Steve writes:

TWiM Audio File with Interactive Transcription

Here is a link to a partial, video I created from the TWiM 06 audio file: I created a video file from the audio file so that I could use the YouTube captioning tool to import an interactive transcript -- minutes five (5) through twelve (12). I created the time-coded transcript using an online tool called Subtitle-Horse, (

If you click the interactive transcript button on the button-bar (Like, Dislike, Add to, etc) just below the video player, you can see how the transcript works. The transcript is indexed, time coded to the audio.

Potential Benefit of Interactive Transcription

The time-coded transcript text could be parsed and placed in a database for easy query. Then all included audio/video files are text searchable and associated to the segment of the source audio/video clip.

Collaborative Transcription

On TWiV a number of people have completed or are working on transcripts. In my experience, transcription is a time intensive process. To lighten individual time commitment, it would be nice to get several people to work collaboratively to transcribe one TWiV audio/video. Although far from perfect, the subtitle-horse online transcription tool could be used for this.

Volunteer to Help Transcribe

As a first step, if interested, I’d be interested in coordinating a collaborative transcription of a TWiV session with one to three others.
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