BacterioFiles 379 - Photons Facilitate Faster Flourishing

This episode: Light increases the growth even of some bacteria that don't harvest its energy!

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Show notes:
Microbe of the episode: Methylococcus thermophilus

News item

Takeaways
Light from the sun is one of the fundamental sources of energy for life on this planet. Plants and other phototrophs—photosynthetic organisms that get their energy mainly from light—form the foundation of the food web, and organisms that feed on them or that feed on organisms that feed on them are all dependent on the ability to capture the sun's rays.

There are other ways to benefit directly from the sun's energy, besides photosynthesis—some microbes have enzymes that use light energy to repair damage to DNA (the same damage that is caused by ultraviolet light), and we use sunlight to synthesize vitamin D.

In this study, however, microbes are discovered to grow faster in the presence of light despite not being phototrophs or producing any light-harvesting proteins. The scientists discover some possible light-sensing proteins, though, that could regulate these microbes' behavior, allowing them to synchronize their growth cycles to phototroph partners in aquatic environments.

Journal Paper:
Maresca JA, Keffer JL, Hempel P, Polson SW, Shevchenko O, Bhavsar J, Powell D, Miller KJ, Singh A, Hahn MW. Light modulates the physiology of non-phototrophic Actinobacteria. J Bacteriol JB.00740-18.

Other interesting stories:

• Finding and capturing electrosynthetic microbes directly from hot springs
• Lignin-eating microbe could be good source for renewable aromatic compounds
• Wood-eating beetle has gut for breaking down wood in microbial production line fashion

Post questions or comments here or email to bacteriofiles@gmail.com. Thanks for listening!

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BacterioFiles 378 - Medusa Makes Marble Microbes

Medusavirus

Yoshikawa et al. 2019 J Virol.

This episode: Newly discovered giant virus from a hot spring turns its amoeba hosts to stone!

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Show notes:
Microbe of the episode: Listeria virus P70

News item

Takeaways
Viruses come in endless different shapes, sizes, and genetic configurations. Even within the group called giant viruses there is a large amount of variety. Many of their genes are unknown, without homology to any other sequences we have acquired in other areas of life. There is great potential to learn interesting things from these viruses.

In this study, a new giant virus is discovered. Like many others, this infects amoebas, and causes them to transform from dynamic, shape-shifting cells into hard little cyst-like circles. This ability gave it the name Medusavirus. It's the first giant virus found in a relatively hot environment (a hot spring), and among other interesting features, it shows signs of multiple instances of gene transfer to and from its amoeba host.

Journal Paper:
Yoshikawa G, Blanc-Mathieu R, Song C, Kayama Y, Mochizuki T, Murata K, Ogata H, Takemura M. 2019. Medusavirus, a novel large DNA virus discovered from hot spring water. J Virol JVI.02130-18.

Other interesting stories:

• Bacteria on frog skin have antifungal potential
• Phages could enhance effectiveness of antibiotics against pathogen biofilms (paper)
• Cement-generating bacteria could make coal ash easier to store safely

Post questions or comments here or email to bacteriofiles@gmail.com. Thanks for listening!

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BacterioFiles 377 - Distributed Defense-Defeating Devices

This episode: Newly discovered CRISPR-inhibiting genes are found in many different bacterial groups!

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Show notes:
Microbe of the episode: Borrelia mazzottii

News item

Takeaways
The discovery of the microbial immune system, CRISPR-Cas, changed many things about the way we think of microbial ecology and interactions with microbe-infecting viruses. The CRISPR-Cas system can learn to detect new threats by capturing bits of their genetic sequences and using these to target the Cas proteins to chop up any such sequences that make it into the cytoplasm. This can greatly increase microbial survival in certain ecosystems in which viruses regularly kill a large percentage of the microbial population.

To overcome this defense, a virus has to adapt, either by acquiring mutations that change its sequence, thus escaping detection, or by acquiring anti-CRISPR proteins that shut down the microbial defense directly. These possibilities make the complex ecology even more interesting.

In this study, scientists develop a clever method for screening for new anti-CRISPR genes, and go searching for them in samples from various places (soil, animal guts, human gut). They find several new examples, which turn out to be found in many different kinds of species in many different environments.

Journal Paper:
Uribe RV, Helm E van der, Misiakou M-A, Lee S-W, Kol S, Sommer MOA. 2019. Discovery and Characterization of Cas9 Inhibitors Disseminated across Seven Bacterial Phyla. Cell Host & Microbe 25:233-241.e5.

Other interesting stories:

• Figuring out how phages gain new hosts (paper)
• Yeast cells modified to produce cheap medical cannabinoids
• Type of bacteria that digest parasitic roundworms from inside out

Post questions or comments here or email to bacteriofiles@gmail.com. Thanks for listening!

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BacterioFiles 376 - Pressurized Pollutant Pulls Products

Bacillus megaterium
By Osmoregulator, CCBY-SA 3.0

This episode: Supercritical carbon dioxide and bacteria that can grow in it make a great combination for biofuel production!

Download Episode (9.4 MB, 10.2 minutes)

Show notes:
Microbe of the episode: Flexibacter aggregans

Takeaways
Biofuels are an important part of humanity's move away from non-renewable resources. They have a higher energy density than batteries are yet able to achieve, giving them significant advantages for transportation purposes in which tapping into an electric grid isn't possible. Depending on the biofuel, they also have the advantage of existing infrastructure: we don't need to build a whole new system of charging or refueling stations, but can use the systems already in place.

However, biofuels as a collection of technologies still need some refinements. Yields for the more potentially sustainable approaches are low, and the lower the concentration of a soluble fuel, the more difficult it is to separate it from the non-fuel components of a fermentation. Microbial products also face the risk of contamination of a fermentation by unwanted organisms that use up the substrate without producing desirable products.

In this study, supercritical carbon dioxide is considered as a fix for both of these problems. The gas is pressurized to a point at which it is indistinguishable from liquid. A strain of Bacillus megaterium is specially selected as capable of growing and fermenting in this environment, while contaminants are inhibited. The solvent potential of supercritical carbon dioxide also serves as a way to extract the biofuel product—in this case, isobutanol—from the aqueous part of the culture medium. While it needs some development, this approach yields promising results.

Journal Paper:
Boock JT, Freedman AJE, Tompsett GA, Muse SK, Allen AJ, Jackson LA, Castro-Dominguez B, Timko MT, Prather KLJ, Thompson JR. 2019. Engineered microbial biofuel production and recovery under supercritical carbon dioxide. Nat Commun 10:587.

Other interesting stories:

• Yeast adopted useful iron-capturing bacterial protein

Post questions or comments here or email to bacteriofiles@gmail.com. Thanks for listening!

Subscribe: Apple Podcasts, RSS, Google Play. Support the show at Patreon, or check out the show at Twitter or Facebook.