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.
Dear TWiM Team,
I just finished listening to the TWiM 35 on LPS in Vibrio (among other topics). Dr. Elio Schaechter mentioned a field in Microbiology that I think is of great interest to the scientific community and should definitely be covered in a podcast. The topic is: Outer Membrane Biogenesis in Gram-negative bacteria. For decades people have been hypothesizing and trying to find an evolutionary link that would answer the following questions: how did a second membrane in bacteria come about and was the last universal common ancestor (LUCA) a single or double-membraned organism. These questions are extremely difficult to address and rely heavily on bioinformatics and phylogenetic analysis.
I'm the first author of the paper that I'm suggesting here as a resource for a potential podcast. I've read extensive amounts of scientific literature before the paper was finalized and published in Cell to realize that currently, there are no favored hypotheses and the very few hypotheses that exist are highly controversial. In our paper we structurally characterize (using electron cryo-tomography) the process of endospore formation. The process is typically thought of as exclusive to Gram-positive bacteria members of the phylum Firmicutes, however, we imaged a Gram-negative organism (Acetonema longum) that is also able to sporulate! Through our structural studies, phylogenetic profiling and biochemical analysis we showed that A. longum possesses a true outer membrane. Not only that, after sporulation, the spore is surrounded by two membranes both of which originated from the inner membrane of the mother cell. Upon outgrowth, the second membrane of the spore becomes the outer membrane of the bacterium and therefore is remodeled from and inner into and outer membrane. These are fascinating new results that may provide us with a missing link between Gram-positive and Gram-negative bacteria and give insights into how an outer membrane may have evolved.
Here are a couple of links to the paper I'm suggesting and a commentary by Dr. W. Vollmer on this work:
Dear Prof. Schmidt, I listened the podcast in Microbiology that you recently contributed together with Vincent Racaniello, Joseph John and Elio Schaechter. You made a very nice summary and commentary of the International Symposium on Staphylococci held last August in Lyon.
Furthermore, I would like to thank you for all your nice words about the symposium that we organized and on our recent opinion paper titled “Inferring reasons for the failure of S. aureus vaccines in clinical trials” and published in Frontiers Cell. Inf. Microbio.
Fabio Bagnoli, PhD
Novartis Vaccines & Diagnostics
Hey TWIM-MERs -- this is from a wildlife rehab newsletter, thought you might be interested:
MRSA in Wildlife
One of the most notorious and hard-to-treat bacteria in humans has been found in wildlife, according to a new study in the Journal of Wildlife Diseases. Researchers isolated methicillin-resistant Staphylococcus aureus (MRSA) in two rabbits and a shorebird. Wild animals may act as an environmental reservoir for the disease from which humans could get infected.
Molecular typing of the isolates showed that the shorebird carried a hospital-associated strain of MRSA, while the rabbits had community-associated strains. The rabbits' MRSA also was resistant to tetracycline, which is common in farm animals.
Perhaps most troubling of all was that one of the pigeons carried a Staphylococcus bacterium that, while still sensitive to methicillin, was resistant to the antibiotic vancomycin. "Vancomycin is used as a last resort in MRSA infections," says study co-author Shylo Wardyn, “and vancomycin-resistant staph strains are rare in humans.” Abstract: http://www.jwildlifedis.org/content/48/4/1069.abstractlink
Happy Halloween greetings Twim Team.
For a slightly microbiology themed Halloween costume I constructed a Plague Doctor mask.
You can see its construction on the instructables site:
Comment: I feel like this issue is quite broad and interesting and was hoping that ocean geoengineering might be worth discussing. It's my understanding that scientists are wary of such approaches, to say the least, but this event seems to demonstrate a certain necessity for the international community to come to terms with geoengineering and sort out strategies and methods. As a layman, I'd be very interested in what you guys have to say!
Quick excerpt from the beginning of the article:
"A controversial American businessman dumped around 100 tonnes of iron sulphate into the Pacific Ocean as part of a geoengineering scheme off the west coast of Canada in July, a Guardian investigation can reveal.
Satellite images appear to confirm the claim by Californian Russ George that the iron has spawned an artificial plankton bloom as large as 10,000 square kilometres. The intention is for the plankton to absorb carbon dioxide and then sink to the ocean bed – a geoengineering technique known as ocean fertilisation that he hopes will net lucrative carbon credits.
George is the former chief executive of Planktos Inc, whose previous failed efforts to conduct large-scale commercial dumps near the Galapagos and Canary Islands led to his vessels being barred from ports by the Spanish and Ecuadorean governments. The US Environmental Protection Agency warned him that flying a US flag for his Galapagos project would violate US laws, and his activities are credited in part to the passing of international moratoria at the United Nations limiting ocean fertilisation experiments
Scientists are debating whether iron fertilisation can lock carbon into the deep ocean over the long term, and have raised concerns that it can irreparably harm ocean ecosystems, produce toxic tides and lifeless waters, and worsen ocean acidification and global warming."
Thank you for the great podcasts,
I just found the latest edition of Clinical Microbiology and Infection and read about a concept that is new to me: culturomics.
Maybe you'll be as intrigued as me by this concept. It contrasts well wil all the high-throughput-genomics hype these days. It might be a good article to put on the show (some day?).
Here are the links, I am happy to forward pdf's of the articles to you if needed.
Culturomics: a new approach to study the human microbiome
Microbial culturomics: paradigm shift in the human gut microbiome study
And again, thank you for three great show to walk, commute, run, bike and do housework to:)
All the best,
Registrar in clinical microbiology
Vestfold municipal hospital, TønsbergNorway
I just stumbled upon your podcasts last week and wanted to say that I enjoy them all (TWiV, TWiP, and TWiM). While listening to episode one of TWiM I began to think about the significance of finding human DNA in a bacterial genome. While this discovery is certainly very exciting I do have one question, doesn't the nature of LINEs make this discovery somewhat less remarkable? They are reverse transcriptases, which are built to copy and insert themselves into host DNA. I think this discovery may be due to the fact that LINE elements are very mobile sequences, and N. gonorrhoeae may be the 'victim' in this case. What are your thoughts on this? And would you feel different if the DNA found in the bacterial genome contained a gene for a membrane protein (or other random human gene) instead of a LINE?
TWIV, TWIP, and now - of all things TWIM? it just doesn't get any better. As an adult 'back to schooler' and beginning-again science learner, I can't believe my luck at beginning my ed adventure into science and beyond, during the era of the "Axis of unsee-able" - the TW's. Once I listen to a TW discussion, the book (especially those dratted ch's on microbe-human interactions and all the replication stuff - aarrggh) comes alive. Here I was last week wishing you TW guys had a microbiology podcast, and poof - my prayers are answered! I thought my ears would pop out of my head as I listened along to TWIM #1, and actually understood stuff! This makes learning fun! You guys have a somehow magical combination of hard-core geek-ism, humor, loopbacks to clarify things for the "LlL's" (less learned listeners), and way too cool: all the heavy hitters seem to be gettin' together to chit chat - thanks a 10(-)7th mol or something like that (clearly more to learn!) Let's vote you folks along with Sal Khan as "egalitarian educators" of the year(s)..
(by the way the piece of human DNA stuck in there on Ng thing was really "eerie", as Sal Khan of Khan Academy would probably say. And, the copper thing - why can't microbes eventually get around that, like they get around everything else eventually - temp, salinity, pH, penicillin? Years from now I'll realize this was a dumb question, but for now it has Viagra me wondering).
Hi Vince, was just about to download TWiV when I saw that you have actually released the first episode to TWiM on the microbeworld website and I just can't stop jubilating. I strongly hope this podcast would be successful as TWiV and TWiP and I appreciate your help very much Vincent..You really helping some of us and I just cant thank you enough.
I pray for long life, happiness and good health for you, your family and all your friends helping you out to bring such an imparting tool in our lives and you all will be blessed anytime someone listens to any of your wonderful podcasts. This is just a thank you message and my questions will be following next.
All the best and goodluck.
Ken (BioCrowd) in case you've forgotten me.
Here's a couple of ideas for signing off the show: "Another TWIM is added to the culture." "Another TWIM enters the culture." - Stephen
First of all, congratulations to professor Racaniello and Racaniello Media Corporation for this new initiative. I am a regular TWiV and TWiP listener from Brazil, and just when I had listened to all episodes, you release this new podcast. Now I can only expect This Week in Vertebrates, or This Week in Plants. Until then, let me make my first TWiM question:
Many times I have heard the explanation that the smell that comes after the rain is caused by antibiotics produced by actinomycetes and other bacteria in a silent war for space. But I have never seen a decent reference to support this. People always say it but do not cite any source. Is it true, and do you have a good source for this?
Thank you all for making another fantastic podcast. I hope you inspire other researchers to do the same, or else Racaniello corp. will end up having 10 or more podcasts, and this is monopoly! Best, Atila Iamarino
p.s. thanks also for introducing Futures in Biotech, its a great podcast too and I am impressed. I'm listening to old episodes, from 2006 to 2008 and many of the discussions are about research that I have only heard last year. I'm anxious to get to the new episodes and know what will be published in 2015.