BacterioFiles 382 - Small Scavengers Suck Sizeable Cells

Rhodotorula prey yeast

By A doubt, CC BY-SA 3.0

This episode: Fungus-hunting amoebas have different strategies for detecting and preying on single-celled and filamentous fungi!

Also, a personal note: I'm going to be taking a few weeks off the podcast to be able to take full advantage of spring, but I'll be back as soon as the weather gets too hot.

Download Episode (7.5 MB, 8.2 minutes)

Show notes:
Microbe of the episode: Chondromyces catenulatus

Takeaways
Amoebas in the microbial world are like powerful predators, going around gobbling up whatever they find that's small enough, by a process called phagocytosis, in which they surround their prey with their cell membrane and engulf it. It's similar to macrophages or white blood cells as part of our immune system in our bodies.

The prey of amoebas includes bacteria, large viruses, and single-celled fungi called yeasts. In this study, scientists showed that some yeasts make great food sources for a certain kind of amoeba called Protostelium aurantium, while others either lack nutritional value or hide from the predators by covering up certain recognition molecules on their cell wall.

They found that the amoebas could also consume the spores of filamentous fungi, and could even attack the filaments, or hyphae. In this latter case, instead of engulfing the large filaments, they pierced the cells and extracted their contents, an approach named ruphocytosis, from the Greek for suck or slurp.

Journal Paper:
Radosa S, Ferling I, Sprague JL, Westermann M, Hillmann F. The different morphologies of yeast and filamentous fungi trigger distinct killing and feeding mechanisms in a fungivorous amoeba. Environ Microbiol.

Other interesting stories:

• Finding potential antimicrobials from ant bacteria

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

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BacterioFiles 381 - Chlorophyll Can Convey Cancer Characteristics

Tumor imaging by MSOT
By Peters et al. 2019,
Nat Commun 10:1191, CC BY 4.0

This episode: Pigmented bacteria can be used in a cancer imaging technique that combines light and sound!

Download Episode (8.9 MB, 9.75 minutes)

Show notes:
Microbe of the episode: Streptomyces bellus

Takeaways
Because "cancer" is a general term that describes many different forms of disease affecting different cells in different parts of the body, effective cancer treatment relies on understanding the location and physiology of the cancer in a given patient. New imaging technologies for diagnosis and analysis of cancer and for cancer research can be very valuable, especially if they don't require big investments of money and space.

One promising imaging technology is called multispectral optoacoustic imaging, or MSOT. This uses pulses of light to create vibrations as pigments in tissues absorb the light and undergo thermal expansion; these vibrations are then detected by ultrasound technology. This approach allows good resolution and depth of imaging without large equipment like MRI machines, but the best results require adding pigments into the body.

In this study, scientists showed that the photosynthetic pigments of purple non-sulfur bacteria can be useful in this optoacoustic imaging, providing a somewhat long-term, nontoxic approach. It proved especially interesting when they discovered that the wavelength spectrum changing over time was an indication of macrophage activity in the tumors.

Journal Paper:
Peters L, Weidenfeld I, Klemm U, Loeschcke A, Weihmann R, Jaeger K-E, Drepper T, Ntziachristos V, Stiel AC. 2019. Phototrophic purple bacteria as optoacoustic in vivo reporters of macrophage activity. Nat Commun 10:1191.

Other interesting stories:

• Figuring out the structure of bacterial nanowires

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.

BacterioFiles 380 - Plant Promoter Produces Polymer

Herbaspirillum-like bacteria
in banana plants
Scientific Figure on
ResearchGate. CC BY-NC 4.0

This episode: A microbe that boosts plant growth needs to make storage polymers for both itself and the plant's sake!

Download Episode (7.1 MB, 7.75 minutes)

Show notes:
Microbe of the episode: Suid gammaherpesvirus 3

Takeaways
Bacteria that promote plant growth are fascinating and not too hard to find. Plants and microbes make good partners by each contributing something the other needs. Plants make sugars via photosynthesis that microbes can use as food, and microbes can gather nutrients that plants can't make, can drive off pathogens, and can contribute to plant growth in other ways.

However, plants aren't making sugars all the time, because the sun goes down every day. So what do partner microbes do at these times? In this study, a beneficial microbe Herbaspirillum seropedicae was found to produce a storage compound called polyhydroxyalkanoate, or PHA, that it could use to store food for times of scarcity. Mutants of this microbe that could not make the storage compound weren't very beneficial for their plant partners.

Journal Paper:
Alves LPS, Amaral FP do, Kim D, Bom MT, Gavídia MP, Teixeira CS, Holthman F, Pedrosa F de O, Souza EM de, Chubatsu LS, Müller-Santos M, Stacey G. 2019. Importance of Poly-3-Hydroxybutyrate Metabolism to the Ability of Herbaspirillum seropedicae To Promote Plant Growth. Appl Environ Microbiol 85:e02586-18.

Other interesting stories:

• Probiotic could help prevent viral infection (paper)
• Some bacteria can cut off their propellers when lacking food to power them

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.