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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 143 Letters

Peter writes:

Greetings TWiM Team

Thinking about the revised estimates for the number of bacterial and human cells in the body from 10:1 to about 1:1, I was wondering what the microbiome cell to self cells ratio is for different species.

I presume that it would depend on diet with herbivores  having a higher proportion of microbial cells than omnivores and that omnivores would have a higher proportion of microbial cells than  carnivores. I would guess that the smallest gut microbiome  would belong to humming birds that exist on nectar and insects.

Has the size and diversity of the microbiomes of different species ever been investigated?


Roman writes:

Dear TWIM hosts,

Love your podcast, keep it up.

Could you give me a name or link to the sound track you use? You say it's by Ronald Jenkees, but it is still hard to find.



Intro: Remix to a Remix from his first cd, Ronald Jenkees.

Outro: Stay Crunchy from Disorganized Fun

Find them at


TWiM 142 Letters

Carole writes:

Dear Vincent and hosts of TWIM,

I am a long time listener and fan of your weekly TWIM podcasts. I really enjoyed the latest episode in which you discussed a paper by Kelly Wrighton and colleagues, and was especially happy to hear you talk about chemistry! On that note I'm writing to tell you and your listeners about a seminar series entitled the Chemistry of Microbiomes, organized by the Chemical Sciences Round Table of the National Academies of Sciences. In separate workshops the series addressed Earth, Marine and Human Microbiomes, and we were fortunate to have Kelly Wrighton speak at the Earth Microbiome seminars. The talks have been archived at . If you tune in next Wednesday, Dec. 7, you can watch the final talks of the series in the All Systems seminar to be held in Washington DC.  Listeners can email or tweet questions during the talks.

Wishing all of you happy holidays.


Mark writes:

Hi Michele

I am that rare thing, a British baseball fan (and ASM member), and I have been rooting for the Cubbies this last post-season.  On top of their amazing win, my American post-doc, Morgan Feeney, just pointed out that, in the very early 1900’s, before they were called the Cubs, the Chicago NL team were briefly called the Chicago Microbes (due most likely to Chicago’s famously bad sewage system of 120 years ago – basically the river).

Take a look at this link:

Also the attached newspaper clipping.

Best wishes!


Professor Mark J. Buttner

Head, Department of Molecular Microbiology

John Innes Centre



Supti writes:

Hello I had a question regarding specialized transduction, what are the consequences of the portion of the genome of phage which remains attached to bacterial chromosomes as a result of faulty excision? I mean does it lead to any kind of useful mutation?

Thank you


TWiM 141 Letters

Tom writes:

For the article letter about microbial batteries, I think CV refers to Capacitance times Voltage, which is stored charge. In electronics, current is abbreviated I not C.

The claim in the letter got me thinking about microbial batteries and I wrote a blog post about their theoretical capacity. They have potential!

Nancy writes:

Hello TWIM team,

Since discovering you all I have been binge listening to TWIP and TWIM. Most enjoyable to listen to the discussions and very good leavening for the mind.

The point I wish to make seems so blindingly obvious that I hesitated to write to you about protecting patients from infections in the hospital. All this hand sanitizing and of its cleaning goes on but where is the attention paid to the patients' hands?

There is no hand sanitizer offered before meals or on hand by the patients' beds. I have not seen this visiting my local hospital as patient or visitor.

Maybe I am completely wrong and this protocol is in place  but if not this is a big missing component.

Thanks for the hours and hours of fascinating knowledge.



TWiM 137 Letters

Daniel writes:

Long time listener, first time writer. It has been far too long for me to offer my sincere gratitude for the podcasts. Some years ago I was a welder working a very boring job and I managed to get through my day by listening to podcasts and lectures. These podcasts and lectures convinced me to give up my boring day job and go to the excitement of university. There I progressed in biochemistry and developed a love for science, and went on to a Masters and am now working on my pHD. You can’t imagine the excitement and fulfillment when I heard our paper was featured on your podcasts (That one about diderms and monoderms). All that work seems to have paid off and it truly feels like I am a real scientists now.

So thank you!

I feel I need to give a shout out to my pHD program. The pasteur institute has an international pHD program where they call for applicants every year and provide an amazing 3-year pHD program. This institute is probably one of the best for doing science and I couldn’t picture a better pHD. Here is a link:

As for our paper thanks for the nice overview. To address Dr. Schaechter’s comments about seeing how the systems compare between E. coli and the Negativicutes I have this for you:

First of all remember E. coli is one of the most “evolved” bacteria there is. They have a large genome and incredibly complex systems (probably not the best model system due to that, but that’s history). See attached tree (It is pretty rough, so don’t make a big deal about the deep nodes, Monoderm phyla in grey, No root so don’t pay attention to what is ancient). The Negativicutes are so extremely distant that it is amazing they posses the same systems and any genomic synteny. However with the pili (some supplemental figures in the paper) it is clearly the same system. The BAM/TAM system is drastically different and matches the more closely related Fusobacteria, and other Terrabacteria beautifully. We have a lot more to say on this story and we will have more fun articles coming months :)

Daniel Poppleton

Anthony writes:

Climate influence on Vibrio and associated human diseases during the past half-century in the coastal North Atlantic.


TWiM 136 Letters

Steve writes:

Hi Microbophiles,

Here's an interesting little historic snippet from The Lancet.
Venerable bacteria: In another interesting history of science piece, The Lancet gets bully over Koch's bovine TB samples--but not over the tragedy of him advising that this form of the pathogen was not significant for human health, and thus delayed the introduction of basic meat and milk hygiene and testing.

It seems that the good and the great nearly always put their foot in it somewhere!

All the best,


Where it has been hot and sticky for some days (and nights: most people don't have air conditioning in UK homes.).   Incidentally: how does one get black mould stains out of pillowcases? Yes: that sticky!  :/

Anthony writes:

"The plague of 1665-1666 was the last major outbreak of bubonic plague in Britain, killing nearly a quarter of London's population.
It's taken a year to confirm initial findings from a suspected Great Plague burial pit during excavation work on the Crossrail site at Liverpool Street.
About 3,500 burials have been uncovered during excavation of the site.
In Germany, molecular palaeopathologist Kirsten Bos drilled out the tooth pulp to painstakingly search for the 17th century bacteria, finally obtaining positive results from five of the 20 individuals tested from the burial pit.
"We could clearly find preserved DNA signatures in the DNA extract we made from the pulp chamber and from that we were able to determine that Yersinia pestis was circulating in that individual at the time of death," she said.
"We don't know why the Great Plague of London was the last major outbreak of plague in the UK and whether there were genetic differences in the past, those strains that were circulating in Europe to those circulating today; these are all things we're trying to address by assembling more genetic information from ancient organisms."

Steve writes:

Hi TWiM team,

Just to say thanks for your interesting discussion of the points I raised regarding uses of gut gas analysis/fingerprinting, and hand hygiene in the context of declining use of copper coinage.

One or two of my points weren't expressed very well:

I hadn't intended to convey the sense of a general increase in the spread of infectious diseases‎, but more in the increase and spread of antibiotic resistant strains. The widespread use of antibiotics and antiseptics in hand and surface cleaners has, most likely, produced the general decline in infection that the team noted, but, previously, there would have been a good deal of copper in circulation on people's hands in addition; and bacteria on the fingers would frequently be brought directly into contact with copper metal, which would kill them before they could be passed on. This may have held back the spread of antibiotic resistance.

It does strike me, that, from what I hear in your podcasts, antibiotic resistance does not have to arise denovo very frequently: it is a part of the general  variation which just needs to be selected by knocking out the‎ remainder. Also, you have noted that horizontal transfer, even between unrelated bacterial species, begins almost immediately, when they are mixed  together. Given this, it seems to me that antibiotic resistance has taken a surprising long time to spread and become a major health concern. It could be, that the metals in our environment were holding it back, until recently, when our metal pipes and handrails were replaced with plastic and plastic coatings, and we reduced our use of coins in favour of plastic cards, paper, and electronic transactions.

The second remark--about mosquito's stance on it's legs--left me puzzled as to why it wasn't understood by the team. Having spent many a night scanning my walls and ceilings for nearly invisible mozzies, that whine in one's ear, as soon as the light is turned off, and then vanish again when it's turned back on, I had become very familiar with the, two back legs in the air‎, stance of the common mosquitoes, here.

I had assumed this was a general thing among those that hold themselves at an angle to the surface, but, following your team's confusion, I checked more Google images, and see that there are, indeed, as many pictures where all six legs are used, as there are of those where the back legs are held aloft or just left loose. I don't know how many species I'm looking at though.

One could imagine that the back legs might be needed for purchase while the proboscis was penetrating the skin, but then can be relaxed as‎ grip is transferred to the proboscis itself; but those on my walls hold their back legs aloft though they are not feeding, so it seems to be a preference, or have a specific purpose.   I had speculated that the raised legs may serve as aids to sensing air currents, and so contribute to the mozzie's uncanny ability to avoid swatting hands! Possibly the stripy legs of some species could be used in signalling too.

Anyhow, I have always found this stance an interesting observation. I further note, that the same places where the mozzies land, are frequented by Pholcus 'daddy long legs' spiders, but they rarely get caught. Both the spider and the mozzie have the same habit of doing high speed push-ups on their spindly legs, from time to time. I hope it's not catching!  :)

Hope this explains my points a bit better.
Many thanks for your, always thought provoking, podcasts.

(Weather now uniformly grey, cool, and still.)

Vincent: I asked Kristen Bernard at UW-Madison:

Mosquitoes often don't use the last pair of legs, but will use all six for balance especially once blood fed.


TWiM 135 Letters

Reed writes:

Dear Vincent, Elio, Michael, and Michelle,

I've just recently finished TWiM number 133 and wanted to comment about the use of the term "secondary metabolite" throughout the episode and often in the primary literature. Michael pointed out that a secondary metabolite is a molecule that is produced by an organism as it reaches stationary phase.

This is actually one of several characteristics that are used to define what a secondary metabolite is. Other common features are that secondary metabolites are "small" molecular weight compounds, they are not involved in the normal growth of an organism, and that they are dispensable for growth and fitness of the producing organism.

However, while many of these molecules are non-essential under laboratory conditions, they may be critical for survival under natural conditions. For example, siderophores are critical for scavenging iron under iron-replete conditions. Pyocyanins produced by Pseudomonas aeruginosa are involved in redox homeostasis. Bacillaene produced by Bacillus subtilis is essential for defense against lysis caused by Streptomyces sp. Mg1 and predation by Myxococcus xanthus. Lugdunin highlighted in the episode is another such case.

Additionally, many of these molecules are produced during multiple growth phases and are not exclusively limited to stationary phase. Taken together, these few examples illustrate that secondary metabolites may be far from "secondary" in their physiological importance. It is for these reasons and more that many have taken to calling these wonderful molecules "specialized metabolites"!

Thank you for the podcast!

Anthony writes:

He withered away for 7 years. Doctors didn’t realize his passion was killing him.
According to the paper, when doctors initially tried diagnosing the man’s illness, they overlooked his daily hobby: playing the bagpipes.
Tests conducted on the man’s bagpipes found a slew of fungi and yeast living inside the musical instrument.
Inside the air bag was a mixture of Paecilomyces variotti, Fusarium oxysporum, Rhodotorula mucilaginosa,and Penicillium species. In a petri dish, they formed a psychedelic swirl of green, orange and red mold.
Henrik writes:


thanks for providing so much information!

I have a mast cell activation syndrome and recently was by Prof. Dr De Meirleir in Brussel to look for chronic infections as a possible cause for mast cell dysfunction. He found that I have positive serology for Tularemia, so it seems that I was in contact with the any of the F. organisms.

He did some follow up tests I will only get to know next month.

My question is: Can the organism F.T. establish chronic infections or will the host either always die or kill the pathogen completely?

Thank you very much,


I asked Katy Bosio:

There have been a few reports of chronic infections with Tularemia, but I think those were largely restricted to the early days of antibiotic therapy (see Public Health Reports, 1926, 41:1341) and were symptomatic.  They also started with a known exposure to F. tularensis.

It sounds as though the listener may be asking if F. tularensis can cause sub-clinical disease, i.e. infection without detected signs of illness.  There is not much data on this either, but there have been some reports suggesting that it is possible (Emerging Infectious Diseases, 2010, 16(2); Emerging Infectious Diseases, 2015, 21(12)).  


Catharine (Katy) M. Bosio, PhD
Senior Investigator
Immunity to Pulmonary Pathogens Section
Laboratory of Bacteriology
Rocky Mountain Laboratories
Hamilton, MT


TWiM 134 Letters

Nathan writes:
Dear Vincent, Elio, Michele & Michael,
Thank you all for the wonderful podcast!  It’s a great gift to humanity and science communication.  It would be great if you could discuss the really interesting paper by Din et al recently published in Nature.  TWiV listeners know about viral-based anti-cancer therapies and successes such as Amgen’s T-Vec.  Now here’s a bacterial based approach.
Keep on podcasting.
Nathan in Chapel Hill

Cindy writes:

Hi TWiMmers,
I'm finally writing to say how much I enjoy your podcast after a year of listening. I was just listening to the latest episodes for a while because I'm lazy and you have years of podcasts to go through... but you weren't updating fast enough to satiate my appetite. I have been going through your feed for the last couple of weeks (while still listening to the latest updates) and cannot believe the goodies I've been missing out on! I considered #11 to be my favorite until I listened to #131 just today. I try to take anything about the microbiome with a grain of salt, as Elio suggests, but find myself picking my jaw off the ground after each episode that focuses on it. The way you TWiMers present the data and explain the experiments (either good or bad) make them easy to understand for us laymen/women. I knew nothing about bacteria other than there are really gross ones in bathrooms until this last year when I decided to go back to school for a marketing degree and fell in love the first time I looked through a microscope. I'm 27, a first year college student, mother of one, starting a career in Microbiology from scratch and still can listen to your podcast with some understanding because of how well you present it. Every episode I listen to keeps me hungry for more and so intensely curious about the world that is all around us and is so vitally important, as we continue to find out, that I sometimes finish an episode almost giddy with excitement over the work that is being done. Episode #131 is one of those episodes. Thanks for taking the time to spread the good word that is science and thanks for keeping it accessible.

Keep up the good work!

Steve writes:

Hi Microbies,

A research snippet mentioned in this week's Lancet, prompts me to get in touch with a couple of questions I've been meaning to run by the team:

Firstly: I've been wondering, while reading and hearing of all the remarkably technological work going into characterising the gut microbiota by brute force processing, why I never hear of 'gut gas fingerprinting', as a more simple method of characterising the makeup and activity/health of both the microbiota, and the host?

It seems to me, that a 'cheap and cheerful'‎ GCMS readout from a fresh faecal sample, could actually prove to be a very useful diagnostic and research tool--particularly so, if trace gas composition could be associated with particular microbial communities and disease conditions. Maybe microbiome researchers should routinely do GCMS on their samples when they do their PCR etc: it could reap great rewards as the data mounts up.

This actually struck me, when I was listening to Dickson discussing the 'foul smelling diarrhoea' associated with Giardiasis: most people probably think that all faeces smell foul, so how is the patient to describe degrees of foulness? This could be quite important to me, as I am disabled by severe bloating in combination with severe cramping in the small intestines, but, there seems to be no way on offer from doctors, to find out what is going on, other than occult blood tests and x-rays that show nothing.‎ Colon checks out OK, but what of the rest?

I've had breath tests that were indicative of overgrowth, but not of what by (This did not respond to penicillin antibiotics.).  At the same time 'normal' bowel movements can give off a powerful, almost petrochemical/mercaptan odour, which, most certainly is foul.   It seems to me, that routine GCMS‎ fingerprinting, could remove the uncertainties associated with describing odours, and be a valuable aid to diagnosis and identification of problems in hard to reach places.

The article that reminded me to ask about this, was actually on the issue as to whether, or how much, microbial gases 'control us'‎ by the production of 'gasotransmitters', so it looks as if gas and trace gas analysis could determine good biomarkers for all manner of purposes.  

Come to think of it, I do remember that someone was trying to develop an 'artificial nose' for detecting disease states in similar manner to the dogs that we hear of that can smell skin cancers. So gas/VOC sampling, both internal and external, surely should be getting at least as much attention from microbiologists as whole microbiome DNA, proteome, etc. sequencing?

What do you think?

Secondly: I've been listening to your various conversations on hand washing and ‎the problems attendant on trying to control spread of infections. I've been meaning to ask two things:

1: How the heck does anyone clean under fingernails, when most bathrooms do not seem to contain nail brushes, and the brushes available in shops become like the one in the attached picture, very quickly?  The only way I've ever really got my nails clean was with a high pressure flat jet on the garden hose--which is not really practical indoors. Perhaps there is scope for some kind of bathroom jet nail cleaner? Or an entire rethink of the bathroom basin to make it an enclosed device for jet-sterilising hands only.

2: For Michael:  As a child, I remember being, frequently, told to wash my hands after handling money (which in those days meant big coins), because 'you don't know where it's been'. Despite this, most kids would have a few big copper coins in their pockets, most of the time, and be continually handling them with sweaty fingers (Especially holding them still while running!).   

Children, and a good many parents, would have had copper, silver, and brass in appreciable concentrations in the sweat of their hands, almost all the time.‎ Far from being agents of disease spread, it seems likely that the universal use of copper and silver coinage must have played a big part in the prevention of disease spread.

(Actually, a lot of people don't even seem to like pockets these days, so that might be another confounding factor I hadn't considered. Perhaps the answer is to make mobile phone covers of copper: phones rarely leave most people's hands?)

In addition to this, there was pretty much universal use of copper and brass for door handles, hand rails, curtain rails, door push plates, pots and pans, keys and locks...   We were constantly charging ourselves up with microbe killers wherever we went, and this was obvious from the beautiful sheen/patina on 'public metal'‎ created by the touch and sweat of many thousands of hands.   How quickly those coins went dull and green when left at the back of drawers...   (How easy it is to recall the taste of copper! My mouth waters at the thought! I wonder if today's children know that taste?)

So, it seems quite plausible to me, that the switch to paper and plastic money and electronic transactions, and away from the best metal in the coinage that remains, coupled with the near disappearance of decent metal door and window 'furniture'‎, bathroom plumbing, and handrails, could be the single most contributive cause of the modern spread of diseases, by contact.

What does the team think?

Your very good health.


At a sticky 24C, as it's better than opening windows and letting mozzies in!  (Ooh: Which reminds me: Why do they have 6 legs when they only use 4?  :) )


TWiM 133 Letters

Arthur writes:

Hello TWIMers!

I'm a graduate student working in mycoplasmology and I  must say I've been overjoyed to hear the past few episodes mention our tiny friends!

Elio's mention of their unique mechanism of moving ("Gliding Motility") made me think of a recent paper from the group in Japan under Dr. Miyata - you may find the paper quite interesting (attached)! They've done a lot of work on mycoplasma motility, and local US researchers such as Dr. Mitch Balish at Miami University also have made great advances in this field.

In discussion of the Mip/Mib system, one thing that has caused some head scratching in our lab has been why the microbe cleaves the Fab portion rather than the Fc? The human species (M. genitalium and M. pneumoniae) don't have the serine protease (at least based on homology searches) and bind to IgG nonspecifically - it makes you wonder why the microbe has conserved that binding protein? Quite a neat area that needs more work!

Thanks for such an interesting podcast and keeping me preoccupied during my hours in the mouse facility!

Warmest Regards,


Frank writes:

Dear Drs. of TWIM,

Two observations on pili conduction.

TWIM #51 featured Hazel Barton discussing her discoveries of microbial excavation of caves.  Barton’s comments on the role of Geobacter electron transport in speleogenesis would be very interesting.

Secondly bio-batteries would seem to be far ahead of their time.  These energy sources that are so valuable to low C/V biological systems are likely not going to be useful in our crude, relatively high C/V electronics.  I have to imagine that our current electronic technology will eventually discover and utilize biomolecular processes to accomplish computing and communication.  At that time, bio-batteries will come into critical use and we can start to approximate the complexity and elegance of multicellular organisms.

August Gloom pervades the northern California coast where the temperature is Ugh point 7 (15.5C) and the humidity is only a optical tease of much needed falling water.
Thanks for all the education.  Your importance can’t be overestimated!

Best Regards,

Aptos, CA


TWiM 132 Letters

William writes:

Hi TWiMers;

It is a nice late July evening here in Berkeley - 60F/15.5C - no fog, but we have had a bit less than usual summer fog this year.

Ran across this article which is fascinating  because it falls into the category of "what you thought was obvious, in fact is not."

"Lichen: Apparently Happy Couple Really A Threesome"
"Lichens come in two basic flavors. One forms a thin, film-like layer on rocks and trees. The other kind is composed of "macrolichens" that grow big leafy, branching or vine-like structures. It's the latter that seem to harbor the yeast.
The discovery started when Toby Spribille, a postdoctoral fellow in McCutcheon's lab, was studying two lichen species collected from the mountains around the Missoula, Montana campus - Bryoria fremontii and B. tortuosa. The two species are distinguished by the presence of vulpinic acid in B. tortuosa, which also gives it a yellow colour. However, genetic tests showed that the known fungus and alga in both lichen species were identical.
But Spribille and McCutcheon found the genetic signature of a third species - a basidiomycete yeast, present in both of the lichen species but more abundant in the yellow version. They and their colleagues went on to test 56 different lichens from around the world, and found each had its own distinct variety of basidiomycete yeast."
See "Lichen: Apparently Happy Couple Really A Threesome"
Bill (William) Johnston
Berkeley, CA

Anthony writes:

Until quite recently, Potter’s accomplishments and her experiments in natural science went unrecognised. Upon her death in 1943, Potter left hundreds of her mycological drawings and paintings to the Armitt Museum and Library in Ambleside, where she and her husband had been active members. Today, they are valued not only for their beauty and precision, but also for the assistance they provide modern mycologists in identifying a variety of fungi.
In 1997, the Linnean Society issued a posthumous apology to Potter, noting the sexism displayed in the handling of her research and its policy toward the contributions of women.

Christoph writes:

Dear TWiM overlords (in a gender neutral way)!

Michael had a very interesting interpretation of what coccolithophores were, when commenting on Kyle's letter in TWiM 131!

He correctly identified two out of the three Greek/Latin words in there, but that steered him in a in funny direction, as he thought they were rock eating cocci and not Haptophyte algae.

Let's see what I can remember from learning two dead languages in "Gymnasium" (German grammar school):

Cocco-litho-phore consits of "cocco-" from Greek kokkos = berry (score Michael) , "-litho-" from Greek lithos = rock (score Michael) and "-phore" from Latin ferre = to bear / to carry (this one Michael got confused with trophos = feed)

So Michael turned the "Cocci-Rock-Bearers" into "Cocci-Rock-Eaters". Close, but no cigar!

Indeed the, the "Cocci-Rock-Bearers" got their name from carrying tiny scales of calcium-carbonate, the coccoliths (I presume this was close enough to be called "rock" since their fossilised remains makes those impressive cliffs of Dover in the UK). Their ability to turn carbon dioxide into calcium carbonate combined with their high abundance in temperate oceans makes them highly important to the global carbon cycle, but unfortunately also highly susceptible to ocean acidification. One of their prettiest members Emiliania huxleyi has even been featured on TWiM before (TWIM 34

Hope I didn't screw this up too badly and embarrass my former Latin/Greek teachers...

Keep up the great work, the TWiX empire is awesome!

Maybe you could feature more free living eukaryotic microbes (and their viruses)?! It seems like they get lost somewhere in the gap between TWiM and TWiP, but their rare appearance is always a delightful listen (like TWiM 94)!


PS: The weather in Vancouver BC is currently 21˚C, 73% humidity, 0% chance of precipitation and apparently pretty windy with 29km/h (although a quick look out the window can't confirm this..)


TWiM 129 Letters

Steven writes:

Dear Vincent et al,

Firstly, congratulations for keeping up such a wide range of thought provoking podcasts, and maintaining such a tremendous output. I find they all leave me with more questions than answers, which is, I think, a sign of good science.

On the latest TWiM, I listened with fascination to Elio's round up of species able to manage without mitochondria (I wonder: will Wolbachia ever be reduced to the status of organelle?), but then I found myself feeling decidedly uneasy as I listened to the review of the paper on using a phage lysate as a novel antibiotic against bacteria.

Our 'traditional' approach to antibiotics (and, indeed, anti-cancer drugs, and pesticides), through simply prospecting for active chemicals in the environment‎, and then using them in a haphazard way--both through the profit motive, and misuse--has, in every case, led to the development of resistance and the danger of a return of morbidity to pathogens long thought 'tamed'.

Isn't it time we learnt our lesson?   This new attack on the natural resource offered by phage, clearly shows that we have not. By all means, search for an active phage, but, for all our sakes: don't go spiking its guns!

I found myself with a sense of deja vu as I recall my concerns when B.t. products began to be used as pesticides, even though the live bacteria had long been used as a proper biological control--no patent fortunes to be made in that, of course.   

Using the natural process, bacteria multiply in the target species and destroy it from within: using bacterial products as sprays that don't multiply, the pest may or may not absorb a lethal dose, and resistance is much more likely to develop (Applying it via the GM route, pests are still able to sample a leaf, and reject it and go somewhere else: not so if they had swallowed whole bacteria.).‎

No doubt, resistance develops more slowly in insects than with the case of antibiotics and bacteria, but I think that the end result is inevitable: a useful living biocontrol has been rendered ineffective, due to our obsession with finding the active ingredients of everything and using them 'pure'.  (The same thinking was applied to the food industry when 'nutrition' kicked off in the 19C and gave us white bread and sugar, from which we still have not recovered.)

Whilst prospecting for antibiotics has been recently given a second chance through the new methods of cultivating bacteria‎ 'in the wild', it seems clear that there is every intention of going on with 'business as usual', mass producing every new find, and then cashing in until resistance develops.

Meanwhile, other countries have, apparently, been using the much more logical approach, of letting whole phage target, and destroy, pathogenic bacteria, all along.   Why are the 'Westernised' countries not pursuing what would seem to be a much more likely way to  combat bacterial drug resistance than carrying on the way we have been?  [Presumably the drug cos don't see fortunes in that approach.]

The rather lame 'excuse' seems to be that us fussy 'Westernised' people would not accept 'live' viruses inside us, whereas we don't mind poisonous chemical drugs. I think that the willingness with which we shovel 'probiotic' yogurts, and even consider stool transplants, demonstrates that it would not be so difficult to market phage as the next big natural medicine--And in this case, it really would be medicine!

Undoubtedly, phage therapies will have their own intrinsic problems to overcome--getting around our immune defenses for one--, but the fact of their quite long history of use shows that ways have been found.   So: What right do we, who have squandered all our 'magic bullets', have to start stripping down the medicinal phages used by other nations, to their basic components, in order to extract and squander the magic from them too?  

What we witness in the phage lysate paper discussed on TWiM, is the start of an assault on the essential medicinal resources of other nations, that could saddle them with pathogenic bacteria made immune to their natural phages, and, leave them and ourselves powerless to fight disease.   And, in a worst case scenario, we might even upset the entire balance between phage and bacteria that has kept the latter under control for billions of years.

I am, of course, only a lay observer of all this, but it rather strikes me, that playing loose and free with the essential tools and weapons with which phages prevent our world from simply piling up with bacteria, when we know that our own methods always result in resistance‎, is a much more dodgy thing to contemplate, than all those 'gain of function' experiments we argue about.   These, indeed, could be called 'loss of function' experiments, because, used the way we know they will be used, they, indirectly, could result in the reduction in effectiveness of some of the most vital housekeeping components of our ecosphere.

I hope I'm wrong, but I think history is on my side.



Ben writes:

Dear Twimers,

I recently discovered your excellent podcast and have been going back through your archives discovering many gems. My favorites so far include the discussion about the Bobtail Squid with Margaret McFall Ngai in TWiM #10, the discussions of Ehux in TWiMs #34 and #37 and the discussion of Centenulid Flatworms in TWiM #21.

I'm an artist and have no scientific training so I listen without expecting to understand everything, but when things get a little too technical I'm always sure that you all will bring the discussion back around to a point that I can readily understand. This is something I really appreciate so thank you for your effects to clearly communicate the intricacies of the fascinating and exciting world of microbial science.

I recently came across this paper that I thought might be of interest

This is an example of a substance that is generating what seems to be a beneficial alteration of the gut microbiota. I found it particularly interesting that the species involved is Akkermansia muciniphila-one that regulates mucus in the gastrointestinal tract. Given that the mucosal lining of the intestine is an important area for communication between host and microbe I wondered whether the ecology of the intestinal mucosa might be in interesting subject for a future TWiM.

Kind Regards


Sydney, Australia

Anthony writes:

Experimental evidence of a symbiosis between red-cockaded woodpeckers and fungi


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