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TWiM 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.
I am a Clinical Microbiologist, and have really been enjoying the insights and discussion on TWIM and TWIV (and am hoping to get to TWIP soon). I have really found the information being presented helpful, and am wondering if any of the lectures from the hosting professors are available online. I have found some of Dr. Racaniello's lectures in the iTunes store, are any of Dr. Schaecter and Dr. Schmidt's lectures available online?
Thank you for any information, and thank you for the valuable resource you are providing with these podcasts.
Being a retreaded physics/physical chemical/thermodynamic type without any formal education in biology of any kind, I find your podcasts accessible -- even if somewhat hard to get my mind around. Your are good about defining the jargon that exists in every field of science.
I have spent 35 years working in aquaculture (the raising of aquatic animals) in systems whose real performance is controlled by the microbiologic ecology. In my sub-field of recycle aquaculture, I partition this microbiological ecology into separate unit operations like biofilters, where the performance is a little more controllable/predictable, but still would have a metagenomics as complex or more complex than the human gut. I have seen very few papers even attempt to get a handle on these complex system.
In the practical microbiology department, I have developed a series of fluidized bed biofilters that are able to remove some hazardous materials from ground water down to non-detetable levels of < 1 ppb, well below the minimum substrate concentration for the bugs of about 20 ppb. In particular MTBE , a water soluble gasoline additive, enters ground water from leaky underground storage tanks and people can taste it at 50 ppb. In Calif. the political class went ballistic over this minor contamination problem and forced a multibillion dollar solution, which means that gasoline is 50¢/gal higher in Calif that the rest of the country. The political class supported by the press was going on about how MTBE was non-biodegradable and the lawyers were making a fortune.
My experience indicates that very few chemicals are non-biodegradable, if there is energy that a bug can obtain from degradation. If that weren't true, we would be up to our eyeballs with all sorts of refractory organic chemicals.
I heard that UC Davis and UC Riverside researchers has some very slow growing bacteria that seemed to metabolize the MTBE and they were digging up all sorts of leaky underground tanks in my area. Knowing that these bugs had a 10+ day or so doubling time combined with a 10% or so yield, I knew that I had to setup a reactor that could maintain the bacteria while processing large volumes of liquid over very long time periods. It took me 9 mo to get my first bioreactor running using seed from the universities, sewerage plants and every soil around a leaky tank I could find and a continuous feed of MTBE as the only energy source. I ended up making some money growing kg amounts of these bacteria consortia semenax wiki attached to sand grains used to as seed to start up new bioreactors on new sites and went through many bbl of MTBE growing and feeding them. We can go into a bioreactor at 2000 ppb and come out at < 1 ND with a 15 minute contract time.
The trick of obtaining a continuous discharge concentration below the Smin (minimum substrate concentration for the bacteria to break even -- zero net growth) is to have plug flow on the liquid phase of the system and mixed flow on the biological phase. You fatten up the bugs in the bottom at a concentration above Smin and they keep eating when they get moved to the top where the concentration is below Smin. If the inlet concentration gets near Smin, we have to add MTBE to the input water to maintain a lower discharge concentration. Try telling a regulator that you are going to add a pollutant to the water to get a lower discharge concentration and it blows their minds.
The concept of these fluidized bed bioreactors could be an interesting research tool for the dental bugs you have mentioned. You could fluidize small grains of tooth enamel, where effectively every small grain is in free fall in the culture media all the time, and you could see what happens to the consortia as you change the feed composition -- coke vs pepsi vs apple juice vs mouth wash, etc.
Continue the good work.
I am a former molecular immunologist who now works as an attorney doing catastrophic birth injury defense. I can't thank you enough for enriching my drives with TWIP, TWIV, TWIP and TWIM.
As you can imagine, one of the bugs which occupies a lot of my thoughts is GBS and its proclivity for vertical infections of fetuses. I know that in a certain percentage of individuals are colonized and happily walk around with GBS never causing a problem. What I would be really be interested in learning more about is what can make happy colonizers into pathogens. My thought was that perhaps in fighting for territory a bacterium like GBS expresses virulence factors which, in some conditions, allows it to crowd out other flora. Some sort of swarming like event gets it to spread out and it encounters the fetus.
I know this is likely a gross simplification- but if you have any ideas or suggestions for reading I would be in your debt.
Once again- many thanks for the hours of fun.
I have not listened to every episode of TWiM yet, so you may have answered these questions already. If you haven't, though, will you address these two?
What do you think you do differently in your non-professional lives because of what you know about microbiology?
Describe exactly what it takes to create selection pressure on microbes. I'm thinking about the mainstream conversation around microbe-specific antibacterials vs. alcohol-based sanitizers vs. regular soaps, but I'd like to know the general principles with which you approach that line of thought.
I'm a Belgian student in veterinary medicine (I hope my English isn't too bad), and I'm very interested in microbiology. I have a few questions about the last episode of TWiM (and quite a lot about episodes of TWiV, but I'm still in the process of listening to all of the episodes first in order to be sure answers aren't already discussed) :
The first questions are about the Yersinia Pestis infection story : during the explanations about the life cycle of Yersinia, you talked about iron as the main limiting reagent in many infectious processes. Is it only because of the fact that it's not easily available in the host, or is iron a more important reagent than other trace elements like Zinc of Manganese? Also, are the requirements for such reagents the same in bacteria as semenax hoax in eukaryotic cells? I suppose not since there are already some variations among domestic animals, but in that case are the differences important?
The other question is about the microbiome. You talked about the NIH microbiome project and studies about bacterial microbiome. Is there a similar project about a viral microbiome going on?
Finally, could you make an episode about bacteriophages and their relations with bacteria, and phagotherapy?
Thanks a lot for all your podcasts and blogs, it's really informative and feeds my passion for microbes more and more. Keep up this great work!
PS : I plan to do a PhD in microbiology after I get my diploma, but I hesitate between bacteriology and virology, both are so fascinating. How did you choose your area of research, and do you have advices to choose between one or the other?
At the beginning of Twim #28 Michael articulated his love for math and around minute 12 his desire for "ground truthing" the number of times one touches their face. In response I offer the attached article from a colleague at UCB.
I really admired the candid and humble discussion at the end of the podcast about proper attribution of ideas.
With warm regards (-65 C in Berkeley),
I don’t know how I dare to email you as you must be really busy but here goes.
My name is Carol and at 51 have just embarked on a teaching course, my brain cells, I possess a few, are overloaded.
My tutor wants me to use innovative (new) technology in my lesson and write a 4,000 word assignment plus portfolio on the use of such technologies.
In the real world, when I teach, often even basic computers or powered points are in short supply; anything fancier than that is NEVER available but as this is for an assignment we must pretend that we do have it.
I teach food safety and thought that a good way of introducing some tech would be to have a microscope in class but really he is talking does vigrx really work of interaction, podcasts, phone apps, live chat and possibly video clips.
I don’t need anything too techy as this is not biology A level, just food hygiene, therefore something to do with salmonella would be fantastic.
Are you aware of any links, materials, videos on this subject or any ideas on how I could use a microscope that would immediately be able to send what it sees to a computer?
Think of this as your charity work, helping someone less fortunate than yourself (me)
Many thanks and apologies for my forwardness
I'm an undergraduate student and am currently working in Montreal on a co-op where we manipulate yeast to create either the best bread strains, booze strains, or biofuel strains. Because of this, I'm always reading up on new articles about biofuel. I was wondering if you had heard about this: http://www.sciencemag.org/content/335/6066/308.short
and what your opinions might be.
Thanks for making the hours fly by on the train and in the lab.
Dear TWiM Team I came across this New Scientist article on the general disregard for microbial life in conservation and the need for education to counteract negative perceptions of microbial life.
Your comments please.
Dear TWiM team I saw this fascinating paper on how the variety of bacteria populating human skin can influence who mosquitoes chose for their blood meal.
Not really sure if it would be best covered in TWiM or TWiP as falls within the remit for both podcasts.
Composition of Human Skin Microbiota Affects Attractiveness to Malaria Mosquitoes
It appears that mosquitoes tend to avoid people with more diverse microbial communities on their skin as they contain bacteria that produce volatiles that repel mosquitoes.
Presumably once these particular bacteria have been identified then it may be possible to culture them to produce a mosquito repellent, presumably actually growing the culture on your skin would also work as a biological control, though I think it would be rather harder to market given most peoples fear of bacteria.
I just saw this engrossing documentary about lyme disease with a controversy about the existence of a chronic form of lyme disease. The movie might be worth a mention as a listener pick. It's 1 hr 44 mins long and can be seen online at http://www.hulu.com/watch/268761/under-our-skin. A web site with resources and trailer also exists as www.underourskin.com. The movie is several years old. Do TWIM panel members have any current information about the controversy and is progress towards resolution of what is affecting folks with chronic conditions they attribute to lyme being made? Unfortunately, as noted at the end of the movie, several key researchers have died, including one who had detected Lyme borreliosis in brain tissue samples from deceased Alzheimer patients. I would have liked to have them join the TWIM panel and discuss current activities.
First of all, let me congratulate the microbiology crew for bringing up such a fantastic podcast that makes microbiology so much fun. Since Dr. Moselio is very interested in mitochondrion i thought he probably would know the answer for my question. Its known that only mom's DNA is being passed to their progeny what is the best hgh on the market. Its also known that as you age there is continuous accumulating damage to mitochondrion thanks to the oxygen species. Now my point is why doesn't the mitochondrion which is from mom derived after a few rounds of replication accumulate damage and pass to the child. That doesn't happen (else we already would have high damage in mitochondrion). I hope my question isn't absurd.
I also would really love to hear an episode or 2 entirely dedicated to what we know of HIV on TWiV (Just like the malaria sequence episodes in TWiP). IF you do please focus on HIV genome controls by TAT.
On episode TWiM#22 there was a great snapshot of microbiology in clinic. I just am interested to know if Dr. Alfred have experiences regarding Burkholderia cases in infants. We just happened to see some in premature infants. If yes please light the area.
Am sorry for too many questions and comments. Once again thank you for the great great educast.
Al Sachetti answers:
To be honest I never heard of Burkholderia so if I've seen a case of it I never made the diagnosis.
I looked it up and it is more an infection of the immune compromised, especially those with cystic fibrosis. A case in an infant would be particularly unusual from what I can tell. Seems more of a plant pathogen that also infects livestock and is more of an opportunistic human pathogen. Just more proof, it's the microbes that rule the planet.
On another note, I ran into a pediatric ER doc from Chicago last week who told me they are seeing one of the worst Respiratory Syncytial Virus seasons ever. This has been our experience with more cases in the last few months than we have seen in the last 3 years combined. This is in the face of no Influenza infections at all this year.
Might be fun to do a Bench Top to Bedside show with an RSV Virologist and a physician on this one.
Have a great New Year.
Thanks so much for your podcasts. I find I am a person who learns best audibly and have just jumped into the science, history, medical and EMS blogs, I Listen to a podcast called SMART EM by a pair of ED docs, and they covered the issue of UTI in Peds. They do journal and study reviews and the found that there isn't any basis for the idea that untreated UTI causing kidney damage for Peds. I know, I know, but they took the time to ferret out all the info. Anyway, I am enjoying your podcasts. I don't think going back to school is something I can do, but about once a week I go to a class on virology, parasitology and microbiology. The tuition is great. No student loans. No sleeping in class.
Al Sacchetti answered: Jayne is correct and not correct depending on who you read. This is one of those topics that will continue to be debated as it is mostly "soft" science.
It is all based on retrospective case studies so you really can't design what would be considered a good scientific study to prove it. Such a study would involve not treating a cohort of children with urinary tract infections and following them and a second subset of treated children to determine if one group develops more hypertension than the other. Not an ethical study to perform.
The other confounder is that there are multiple other causes of hypertension that may overwhelm the cases caused by infant UTI's.
For me the take home message will not become clear for another two decades. That is how long it will take for this generation of treated children to grow old enough to really look at the epidemiology of their hypertension. (As an aside, it is one of those issues that really will not change our practices since we will always treat a UTI in a child.)
On a different note. What would you think Kamagra Online about doing a TWIV on Hepatitis C with a Hepatitis C Virologist, a Transplant Surgeon, a Hepatologist and possibly a hepatitis C patient? From the Bench to the Bedside type of show.
Take care and continue the great work you do with the all the TW's
Hi Guys - I was wondering if you had seen the following article in about the lack of acorns being produced in the Northeast this year. In it they mention that the lack of acorns in the past is associated with crashes in the mouse population, then, the author says: "And because the now-overgrown field mouse population will crash, legions of ticks — some infected with Lyme disease — will be aggressively pursuing new hosts, like humans."
Currently here in Atlanta our oak trees are producing massive quantities of acorns. Every few years oaks will begin producing lots and lots of acorns in a season - a phenomenan thought to saturate their predators and try to increase the odds that ssome of their seedlings will germinate and take root. Is there any way that you could do a show (or part of) on some aspect of this Oak-mouse-tick-Borrelia story? It has the parasites (ecto - tick, endo-Borrelia) angle and it has this beautiful tie in to local ecology. I know it isn't typically what you do on the show, but if you can do some aspect of it that would be great. I am going to use this story in my non-science major introductory biology course next semester for some active learning in the classroom, and being able have my students listen to another TWIP/M/V podcast as preparation for those classroom sessions would be too perfect. Does Dr Gwadz have an expertise on the ecology of lyme disease maybe?
Thank you for the great shows, keep up the great work!
Georgia Perimeter College
Here is the link:
Here is an article in American Scientist which passes for a pretty good review on the subject: http://www.americanscientist.org/issues/feature/the-ecology-of-lyme-disease-risk/5