… and that in the short-term carbon through microbial form immobilizes already available N, potentially making less available for plants or loss through leaching.
The belief that adding high-carbon mulch locks up nitrogen may yet have some merit, not necessarily in the mulch, but in the microbes!
From Short-term carbon input increases microbial nitrogen demand, but not microbial nitrogen mining:
Although C input promoted microbial growth and N demand, we did not find indicators of increased N mobilization from SOM polymers, given that none of the soils showed a significant increase in protein depolymerization, and only one soil showed a significant increase in N-targeting enzymes. Instead, our findings suggest that microorganisms immobilized the already available N more efficiently, as indicated by decreased ammonification and inorganic N concentrations. Likewise, although N input stimulated ammonification, we found no significant effect on protein depolymerization. Although our findings do not rule out in general that higher plant-soil C allocation can promote microbial N mining, they suggest that such an effect can be counteracted, at least in the short term, by increased microbial N immobilization, further aggravating plant N limitation.
Bacterial cells in carbon-rich media (purple and blue) grow twice as big as those in carbon-poor media (green). New research shows they can grow big, however, only if they can make fats with the carbon.
Fat (lipids) limits how big bacterial cells can be. “If you prevent cells from making fat, they’re smaller, and if you give them extra fat or allow them to make more fat, they get bigger,” said Levin, professor of biology in Arts & Sciences. “Fat makes cells fat.”
“If we hit the cells with an antibiotic that targets fatty-acid synthesis, we really saw a significant drop in cell size” Vadia said.
Also, by turning up FadR, a transcription factor that activates expression of the fatty-acid synthesis genes, the cells got bigger.
“It doesn’t seem to matter what the lipids are, really,” Levin said, “provided you have enough of them. We found we could give the cells oleic acid, a fat found in avocados and olive oil, to supplement diminished fatty-acid synthesis and as long as the added fatty acid got into the membrane, the cells could recover.”
A little place for my stuff | EurekAlert! Science News
Fatty Acid Availability Sets Cell Envelope Capacity and Dictates Microbial Cell Size: Current Biology
Hydrogenation: transform liquid oil into solid fat
Olive Oil Did WHAT to my Triglycerides??!!?? (Pt 2)
When a plant is introduced (accidentally or intentionally, but usually by humans) into a new region, many factors can influence the ability for that species to become established. One major factor at play is the different set of species it will interact with in this new environment—will they work with it or against it? We naturally tend to focus on the negatives; like whether there are enemies like pathogens, predators or other competitors that will control it.
What has received less attention is how positive interactions are affecting the spread of non-native species. For example, we know that the availability of pollinators is important for many plant species. So when a species moves, it doesn’t just leave its enemies behind, it also leaves its friends, its beneficial partnerships.
And it appears that for symbiotic legumes, these beneficial partners matter a lot. Their associated rhizobia matter so much that we can see their impacts on legume species spread at a global scale, across multiple continents and islands.
Read more: Legumes’ microbe relationships hold them back from travelling the globe – ECOS
A new study has found that:
The type of carbon source affects not only the composition and activity of natural microbial communities, but also in turn the types of mineral products that form in their environment.
“We’ve illustrated that as microorganisms alter their environment, their environment then affects the type of microorganisms that are there and their activity.”
Researchers took anaerobic respiration microbial communities and presented them with one of three carbon sources: glucose, a six-carbon sugar; lactate, a four-carbon compound; or acetate, a simple two-carbon compound.
Their analysis showed that a distinct series of changes occurred consistently when microbes were exposed to lactate or acetate-rich environments. However, in glucose-rich environments, they observed varying patterns of changes.
“We think that, because glucose is a larger, more complex compound that can be broken down into many simpler compounds, this opens up more chemical pathways in the community through which it can be used, and that this diverse metabolic potential accounts for the different patterns we’re seeing,” said O’Loughlin.
Impact of Organic Carbon Electron Donors on Microbial Community Development under Iron- and Sulfate-Reducing Conditions