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
Olive Oil Did WHAT to my Triglycerides??!!?? (Pt 2)
The Natural Farmer
Great episode from Jagannath.
Comments: straw tends to be high in lignin which needs white rot fungi to break it down, which requires moisture and gives rotted wood it’s soft spongy characteristic. Straw is probably better as a winter rather than summer mulch which is why I have a rule of thumb to use soft mulch in summer and hard mulch in winter. Grow your mulch in spring for summer! Prune for winter!
Interestingly leaf litter can also almost contain as much lignin as straw. Sugar cane mulch on the other hand has about 1/3 the lignin of straw and corn stalks are half that again, sugar cane mulch has an ideal carbon to nitrogen ratio of 50:1 though. Corn can actually be quite good for building soil carbon so long as the mulch is left in place and a green added to it, like Jagannath’s planned legume companion.
Also, the allelopathic leaves mentioned can be used after a quick 3-day hot compost. Putting them in a black bag in the sun with some urine may work too.
I find legumes like beans are a great indicator of soil bulk density. They tend to thrive in loose soil where air gets the root zone. The other thing Jagannath may be missing for his soil and environment with such dry lifeless soil is the rhizobia inoculant that form the nitrogen-fixing symbiosis in the form of root nodules. Here in Australia there’s a trial going on to match the microbe with the legume so that farmers can inoculate at sowing time, apparently we don’t get the same level of root nodulation and yield compared to other countries because of our microbial species, so efforts are being made to breed and select for them.
Today I also learned that leaf litter suppresses herbivorous nematodes likely by increasing the fungi population that trap them, while on the other hand just leaving roots in the soil increases nematodes and bacteria over time.
Lastly, I like to measure my mulch depth in buried finger knuckle joints. One knuckle joint is good, two is better, three is best! And so is using three different mulches: green, brown and white. Green for bacteria (nitrifying), brown for brown rot fungi (cellulose), and white for white rot fungi (lignin).
As you can probably tell, I consider mulch the most underrated of topics! 😛
This study says that leaf litter was preferred by fungi and root litter by other microbes like bacteria and nematodes, and that herbivorous nematodes were controlled more by leaf litter than root litter.
Probably by the fungi catching the nematodes with lasso! Yeehaw.
It also suggests that cutting plants at the stems and just leaving the roots to feed soil microorganisms may increase nematodes over time, especially when nitrogen or phosphorus is added. Phosphorus is known to negatively impact on fungi populations, while nitrogen amendment can result in plants exuding less carbon from their roots that fungi and other soil microbes feed on, microbes that then fix nitrogen and make other nutrients bioavailable for the plant.
So, if you’re doing a no dig approach to gardening and leaving roots in place, mulch is a must. Whether that’s a carbon source in the form of leaves or a low phosphorus compost mulch or otherwise, basically think of the fungi!
Researchers closely examined the transport of water, substrates and nutrients through the microscopically small hyphae of fungi. They grew the fungi on a culture medium of water, glucose and nitrogen-containing nutrients. The fungal hyphae had to pass through a dry, nutrient-free zone in order to grow through into a new area containing the culture medium. The inhospitable transition zone contained spores of the common soil bacterium Bacillus subtilis. Spores are inactive stages of Bacillus that form when there is insufficient water, food and nutrients available for bacterial growth. The bacteria go into a kind of dormant stage, from which they only awake once the environmental conditions are more favourable for living again. As the fungal hyphae grew through the dry zone, the bacterial spores germinated and they noticed clear microbial activity.
The researchers then ‘labelled’ the water, glucose and nitrogen-containing nutrients in the culture medium in advance with stable isotopes. If these substances were transferred from the fungus to the bacteria, they could be detected using the isotopic marker.
They found stable isotopes of the labelled water, glucose and nitrogen-containing nutrients in the cell mass of the bacteria — which could only have come from the fungi.
Fungi awake bacteria from their slumber
What comes first? The microbes or the bioavailable minerals that supports microbial growth and reproduction?
Nutrition of the amendment and the stimulation of the native community is more important than inoculation of microbes from the amendment
Balance your soil nutrient ratios to maximise use of soil carbon…
The inorganic versus straw (high carbon) + nutrients would take forever to carbon prime in subsoil, possibly why Corinne didn’t see much difference, not to mention the small amount of additional carbon the straw provided.
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
Don’t forget to rotate the view!