Jeanne writes:

Dear TWiM,

With regard to the question about culturing gut microbes from Drosophila:

I was lucky enough to take a sabbatical in the lab of Dr. Angela Douglas ( in the Fall of 2012, where I worked on the gut microbiota of Drosophila.  Her lab found that the diversity of gut microbes in lab-reared  Drosophila is quite low, comprising just 5-6 taxa, almost entirely Lactobacillus and Acetobacter (Wong ACN, Ng P and Douglas AE, 2011. Low diversity bacterial community in the gut of the fruitfly Drosophila melanogaster. Environmental Microbiology 13: 1889-1900. Pubmed link).  These are easily culturable, although they grow better in low-oxygen environments.  Cultivation techniques for these bacteria can be found here:

Hope that helps!



Dr. Jeanne Kagle

Professor of Biology

Mansfield University

Mansfield, PA 16933

Steve writes:

Hi Microbophiles,

Happy New Year (And Happy Birthday to Vincent).

I have to say it was good to hear a TWiM (118) where I understood every word! 🙂   Having bee‎n a mushroom collector in my time, it was like revising the morphology section–right down to the sterigmata!

I had often wondered how the spores managed to ‘stop’ and fall down‎ between the gills, but perhaps the air viscosity is sufficient as Elio says. A further point to note may be that the mushroom cap is elevated on the stipe so as to get the spores above the lamina airflow that hugs the ground, close to, and into the turbulent air that carries them aloft.  [You might also observe that the gills are always gravitationally aligned, even if the stipe is bent: the spores have to be able to fall down unimpeded.]

Where it comes to the assertion of the importance of fungal spores to cloud formation, I have to refer you back to your programme on EHux, and other phytoplankton, where we were told that the production of dimethylsulphide as a result of breakdown of sulphur-containing metabolites, was the key to controlling the World’s weather, as the DMS leads to the formation of sulphate aerosols that act as nucleation foci for water droplets, much as the fungal spores are mooted to do in today’s podcast.

Without reading into this before writing whilst it’s still fresh in my mind, I would suspect that, as they are derived from molecular processes, the aerosol particles may be smaller than even the fungal spores, and give more nucleation foci  ‎per m3 than obtained from even the large number of spores mentioned.   

So, on the whole, I think I am more inclined to stick with the phytoplankton than the mushrooms in importance as rainmakers, though I think that almost any dust particle, including spores, will act as a nucleus too…

…Or do the sulphate aerosols need particles to condense on just as the water vapour does?  :/

Many thanks for all your great podcasts, and I look forward to many more in the New Year, especially as I have now caught up with the story so far on TWiV, TWiM, and TWiP.

All the best,





Steve writes:

Hi Vincent,

          TWIM is one of my top 3 podcasts-an excellent way to relax-thanks for a great job. I enjoyed Bullers drop, fungal spore ejection and discussions of potential life on MARS but what about some discussion of life in Earths subsurface, where most microbes on/in Earth live, at depths down to several kilometers and at very low metabolic rates! They play a major role in geochemical cycles and natural resource formation. The paper below is an old one from Casey Hubert at UoC and talks of bacterial spore transport and so on. I think survival and transport of micro-organisms within and between planets would make an interesting episode for readers. Discussion in more detail of microbial survival on interplanetary transport and landing via meteorites would also be interesting, which you touched on in the spore/MARS episode.

Thanks and best wishes. cheers steve

Hubert, Casey, Alexander Loy, Maren Nickel, Carol Arnosti, Christian Baranyi, Volker Brüchert, Timothy Ferdelman et al. “A constant flux of diverse thermophilic bacteria into the cold Arctic seabed.” Science 325, no. 5947 (2009): 1541-1544.

Peter writes:

Dear TWiM team.

I saw this advert for a two year postdoctoral position for a microbiologist at the UK Centre for Astrobiology, University of Edinburgh and thought it may be of interest to  other listeners.

I do  not have any connection with the University of Edinburgh other than having taken their Coursera astrobiology course.

Here is the description:

A two-year STFC-funded PDRA position is available at the UK Centre for Astrobiology, University of Edinburgh to investigate the behaviour of microorganisms in space, using the International Space Station. Your work will involve understanding the effects of extreme space conditions, including microgravity, on microbial communities and use these data to advance our understanding of how we can look for biosignatures of life elsewhere and develop new methods to look for those signatures. You will work to help develop new experiments using orbital and space facilities. You will lead both laboratory based and theoretical research to apply this research to STFC science. You should also have an interest in technology transfer. Working at the interface between biology and planetary sciences (astrobiology), at Edinburgh, your responsibilities will include advancing work on space experiments and the use of space facilities to carry out research. You should have a PhD in biological sciences.

You will be a member of the UK Centre for Astrobiology. You will play a wider role in developing astrobiology. This includes working on our ‘Astrobiology in the Classroom’ initiative which, through the Astrobiology Summer Academy, involves developing lesson plans with primary and secondary school teachers to use astrobiology as a vehicle to advance science education in the UK. We seek a self-motivated scientist who will play an active role in creating links with space agencies and other astrobiologists. You will also be responsible for supervision, training and oversight of other staff.

The start date is 1 April 2016. This is a fixed term 2-year position.

You can apply here:

The job vacancy is 035130

Geoffrey writes:


    First of all, thank you for reading and commenting on my talmudic question about unleavened bread. I hope that it got some of your listeners thinking.

    Second, I had a few thoughts that I thought might or might not help amplify your discussions in this episode.

1) Thanks for the article of amoebic pack hunting. I think that I’ve heard of similar tactics with other microbes. Dr. Racaniello kept referring to nematodes in a negative sense. One nematode function that he particularly picked on was “parasitism”. I’d like to point out that nematodes are as diverse a group as they are because they occupy nearly every ecological niche available somewhere in the world. While many of them are quite nasty, nearly all are valuable contributors to the environment. Because of the differences in scale, we tend to think of plant-eating nematodes as infestations while we tend to think of plant-eating ungulates as cattle. Also, think about the difference (or lack of differences) inherent in nematodes that graze on bacteria and nematodes that graze on algae. Thinking on their level is probably one of the most fascinating things about this group.

2) One of the reasons that I have a small interest in nematodes is exactly their occupation of so many ecological niches. Dr. DesPommier (if he hasn’t already heard of this) may be interested to know that Dr. Sharanbir S. Grewel (formerly of the Ohio State University) has been working on a method to measure soil health by microscopic assays of nematodes in a soil sample. Unlike many systems that have used nematodes to generate soil health indices, Dr. Grewel’s methodology relies only on identifying the categories of mouth types in the sample’s nematodes. Since these mouth parts are fairly characteristic for the nematodes’ soil services, they are much quicker and easier to identify that species. The numbers and ratios of the service (mouth) types can give a fairly good idea of how “alive” and diverse the soil is. Unfortunately, Dr. Grewel left OSU before I could work with him to develop a gardener’s guide to using this technique and I have not seen that he has published the basics of it yet.

3) Thanks for the article on fungal spore dispersion biophysics as well. I have to say that I disagree with their assessment of evolutionary advantage. I think that:

  1. A) being a point of droplet nucleation would help ensure that the spores could be carried in the clouds further than naked spore because naked spore would be subject to more chaotic and, therefore, shorter overall paths. Genetic dispersion can be an advantage.
  1. B) In the open atmosphere, spores are vulnerable to UV exposure. It seems to me that thicker aqueous coatings would reduce UV exposure and, again, portage inside a cloud would provide some further protection.
  1. C) Being a rain droplet nucleation site would also help ensure that a spore lands with an initial bolus of water to help initiate sporulation. This would take advantage of a short-term survival strategy that requires only an initial exposure to water. It might be that non-ballistosporic spores take advantage of longer-term survival strategy of initiating sporulation only after water has been available long enough to make a water steady state more likely.

4) I suspect that there is a lot that we can learn about hydrophobic / hydrophilic metamaterial surface design from studying these spores.

5) Much of water droplet formation seems to be based on nucleation site chemistry. That might be the mannitol. That might be part of the surface structure of the spore itself. It might be a combination. I saw little reference to this chemistry in the paper. If they aren’t already in talks with someone, then I would suggest that the authors need to collaborate with a meteorological chemist to look at the surface chemistry of the aquated and non-aquated spores more closely. If this hasn’t already been studied in some detail, then the estimates of atmospheric spore concentrations suggest that it should be. The fact that spore surface chemistry changes may be a point overlooked in previous nucleation site studies.

6) In addition to studying spore effects on droplet nucleation in a cloud chamber (I believe that that’s what the warehouse-sized buildings are called, not the atomic tracing chambers), I would suggest that a potentially less expensive test would be a correlational study between the atmosphere and cloud concentrations of the two types of spores versus rain formation based on mannitol biotracer monitoring might be possible.

7) To chime in on Chris’ martian pathogen question, I would say that it might be possible even if there wasn’t a microbial exchange between Earth and Mars. As long as the martian life-form requires carbon, oxygen, nitrogen, and water, I could envision a decomposer-type organism which doesn’t so much hijack the host body but chemically decomposes it and scavenges the chemically-shattered remnants. It could be something along the lines of acid-based hydrolysis which would have the added advantage of liberating needed minerals in the martian soil. The bigger question would be if any extremophilic microbial survivors on Mars could survive the (relative) superabundance of water in Earth organisms. Such extremophilic organisms might also grow so slowly as to be swamped out by the abundance of life in most Earth organisms. On the other hand, if a dead body were left on Mars and mostly dried out, then those organisms would be all over the body like bone worms on a whale carcass in the deep blue terrestrial sea.

Thanks for another stimulating episode!

Anthony writes:

What Happens to Your Microbiome If You Own a Dog

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