Dr. Robert Kelley writes:
Dear Twim Docs,
I just finished listening to the latest episode it Twim on the microbiote's effects on obesity. There was discussion about the use of donor feces in the treatment of human disease. I thought this might be of interest.
Harnessing the Healthy Gut Microbiota to Cure Patients With Recurrent C. Difficile Infection
This study is currently recruiting participants.
Love the show.
Robert Kelley, Ph.D,
I teach high school AP Biology and Microbiology and have a question about ATP sythesis via oxidative phosphorylation in Gram-positive bacteria (and I guess archaens, too). In mitochondria, chloroplasts, and Gram-negative bacteria, it is possible to concentrate cations (hydrogen or sodium) in an enclosed space to drive ATP synthesis through chemiosmosis. I do not, however, understand how this is accomplished in Gram-positive bacteria and have been unable to find a satisfying answer on my own. Some things I found seem to indicate that the cell wall may trap hydrogen ions (I read something about secreted enzymes not gaining function until they made it all the way out of the capsule due to lower than optimal pH levels) or that aerobic respiration only occurs at high efficiency in the deepest layers of biofilms (something about protons concentrating when the attaching surface has a negative charge), which leads me to believe that Gram-positive bacteria are indeed pumping proton
s out into the surrounding extracellular fluid in the hope that they can be used before they diffuse away.
Microbiology is not my native discipline, but I have become enthralled (in no small part due to the TWi family of podcasts) as I try to both improve my Micro course and interject a healthy respect for our evolutionary forebears into the AP Bio curriculum. Any additional information you can provide would be greatly appreciated.
Just to pound on an older discussion topic of hand sanitation here's a link to a recent study that shows gloves didn't help reduce MRSA and VRE infection, link.
Thought this site, livingto100, might be of interest, perhaps to listeners as well. I expect only another 10 years, at best, and now apparently will make it to 97! Hah!
I have three brief responses to TWiM #66:
1) I always enjoy the episodes with all four of you best of all. Every episode is good, but the ones with all four are especially a treat. Thank you.
2) With regard to the subject of what should be meant by "microbiome," I think that the word should refer to the genes, rather than the organisms, in a given environmental context. I do not think that this is what the word currently does mean, but that is what it should mean. There are two reasons for this. First, as Elio noted, the term is currently redundant over "microbiota," and there is nothing gained by having two words that mean the same thing. The second reason is more complicated. Basically, it seems to me that it is possible for the word "microbiome," considered as a catalog of organisms, to become meaningless when pressed too far. That is to say, E. coli K-12 and E. coli O157:H7 are very different organisms. The former has ~4.3 x 10^3 genes, while the latter has ~5.4 x 10^3. Nevertheless, they both classify as "E. coli." This means that, when one speaks of the "microbiota" as a sort of catalog of the different species that live in a given environmental context, one elides over a lot of the diversity that is found there. To speak of molecules instead of organisms avoids this problem. Therefore, it is simply more useful to make the term "microbiome" refer specifically to molecules instead of microorganisms.
3) Michael has a good point about the need for a word that covers both the microbial and the host molecules that interact with each other, but this concept needs its own third term. Assimilating this third meaning into the already confused term "microbiome" would only further tangle up the mess that Elio is rather conscientiously trying to untangle.
Every episode is a treasure. Keep up the good work.
To my valued friends at TWIM:
Having recently read a Watson book on DNA history, I was reminded of an old TWIM episode that included an 'old timer' who gave numerous stories about his work at Woods Hole and Cold Springs Harbor. The episode may have actually taken place at Cold Springs.
Even though I could tell that the history being related during this episode qualified as 'precious', I was clueless. Now, having read this book, I would give my right arm to hear this gentleman tell his stories about these labs in the 50's, 60's and beyond. But…I can't find the darn episode!!! Can you please help?!? I will send you my right arm!
your avid fan and listener, Andy
P.S. it's my own fault of course that I don't have ALL your episodes; most of them continue to fill up my phone and laptop and always will. I realize I can access the few that I reluctantly deleted. Isn't it a law that I would be looking for the rare deletion…
P.P.S. I will spare you the hearty approbations that your show deserve; you must get those all the time. TWIM gives meaning to my life! literally, I guess.