Neeraj writes:

Hi TwiMmanosomes,

                     It was great listening to the latest TwiM and just when I thought I was already amazed to saturation by the diverse world of fungi (thanks for explanation Elio), along came Salmonella BonJovi (and the title “Its my life” totally suits it). I was particularly intrigued by the ability of the pathogen to downregulate the flagellar machinery but was left wondering, if this is probably one of the reasons why flagellin (a component protein of flagella) has never been developed as a vaccine target against gram negative bacteria (kindly update if you think or know otherwise)  Yes… in Infect Immun. 2010 Feb; 78(2): 746–755. Published online 2009 Dec 7. doi: 10.1128/IAI.00806-09 PMCID: PMC2812208 PMID: 19995892  Evaluation of Flagella and Flagellin of Pseudomonas aeruginosa as Vaccines

Victoria L. Campodónico,1,†* Nicolás J. Llosa,1,2,† Martha Grout,1 Gerd Döring,3 Tomás Maira-Litrán,1 and Gerald B. Pier1-

?. And just when I was thinking that maybe the same is true for the LPS O-antigen, along came Elio again, and asked my question (what a Psychic). It was like I was part of a classroom with 50 million questions in my head but now I can only remember 2 of those. I am sure they will come back to haunt me later when I hit the bed . But it’s the kind of mental exercise that I absolutely thrive on and that is why there is nothing more fascinating to me than the mysteriously complex world of the microbes. It’s like anything we can innately and adaptively to try and curb their invasion, the microbes have an alternate mechanism right up their sleeve. So please continue the great work and continue to educate us.

Happy Holidays,


P.S: Thinking of gram negatives, another question that I was thinking was something to do with the usage of gram-negative E.coli for making proteins. I was wondering if we know the precise reason for the preferential use of Gram negative E.coli for heterologous expression of protein? Was it simply because it was the first model system ever used or was there a more rational scientific reasoning behind it? In today’s world several gram positives like Lactococcus Lactis, Bacillus Subtilis etc are also being used for protein production but E.coli remains the favorite model organism. A literature search didn’t yield much clarity, so I thought I will relay my queries to the esteemed panel of TwiM. Thanks for your feedback.

Lisa writes:

Dear TWiM team,

This past semester I designed and taught my first ever undergraduate course on Bacterial Pathogenesis at San Jose State University.

As an avid and long-time listener to TWiV and having done both my graduate and postdoctoral training in virology, the thought of delving into bacterial pathogenesis was daunting to say the least! Where to start?  

So began my TWiM listening and it was been wonderful! In particular, having the opportunity to listen in to discussions by experts in the field on current and fundamental topics in microbiology was absolutely essential. The papers discussed on TWiM provided critical insight into microbiology topics that I could incorporate into my lectures. CRISPR-Cas9, antibiotic resistance, harnessing bacteriophages for antimicrobial therapy, V. cholerae, Type VI secretion systems etc. I included links to relevant episodes during lecture and many of my students began listening and commented on how wonderful it was to have access to these episodes as a resource for their learning.

Beyond scientific content, the career advice was also incredibly helpful. For example, a number of the students were interested in the Clinical Laboratory Scientist program and I suggested listening to TWiM #52 to gain further insight into the program. Please accept my thanks to the entire TWiM team for all the time and effort that goes into these podcasts – they have had a huge positive impact in my little corner of the world.

On a separate note, I ran into Vincent at ASV this past summer and he encouraged me to not give up on my dream of becoming Professor. Twenty-seven faculty applications later, I just recently accepted a tenure-track Assistant Professor position at Midwestern University and I am SO excited to start. There are not words to express how grateful I am for all of the podcasts and words of encouragements over the years – these podcasts truly bring science to life.

Thank YOU!


Lisa Kronstad


Lisa Kronstad, Ph.D.

Postdoctoral Scholar

Blish Laboratory  | Grant Building S164    

Department of Medicine  | Division of Infectious Diseases

Stanford University

Johannes writes:

Dear twim team,

I stumbled in a really non-scientific website (9gag) over an highly interesting article in ScienceNews, which led me to an article in cell (open access!!!) :

Emergence and Spread of Basal Lineages of Yersinia pestis during the Neolithic Decline

Nicolás Rascovan et al. Published: December 6, 2018

It reports the finding of the well preserved DNA of an ancient Y. pestis strain in a Neolithic mass grave in Sweden.

I would like to leave the discussion of this article to you. Your entertaining way of breaking down the paper might help to debunk the reaction it had on 9gag:


Plague DNA is no apocalypse!

Thank you for your tireless work to educate the world!

Best regards,


Leiden, the Netherlands

Rich writes:


First of all many thanks for another very interesting podcast.  

SNVs were mentioned when you discussed the Yersinia paper which made me think of SNPs, and I wasn’t clear what the difference between SNP and SNV was.  

I carried out an internet search and believe that SNP and SNV can be used interchangeably, but if a distinction is made then an SNV is generally used to refer to an individual, while an SNP refers to an SNV that is present in multiple individuals in a population (>1 percent).  I would be interested to know if this is the rule or whether there is something missing.

Many thanks.

Steve writes:

I know you don’t have listener picks on twim but if you did this would

be mine

and the youtube channel