Oxygen comprises one fifth of our atmosphere, and we take for granted that this a good thing. After all, aerobic creatures like ourselves could not exist without free O2. Not all life shares this feeling. Oxygen and its derivatives (known as “reactive oxygen species” or ROS) can wreak havoc on the biochemistry of many microbes. For some obligate anaerobes such as methane-producing archaea, even a small trace of oxygen poisons them irreversibly (see, for example Kiener and Leisinger 1983). Others fall somewhere in the middle. Microaerophiles (e.g. Helicobacter pylori, the cause of gastric ulcers) require small amounts of oxygen but are unable to tolerate full atmospheric concentrations (Bury-Moné et al., 2006).
Why are these organisms sensitive to oxygen?
Not very permaculture aye? Lots of mystic hand waving? Well… read on.
Ever wanted to know how “Preparation 500” is prepared? Or what’s in the end product?
The material was found to harbor a bacterial community of 2.38 × 10-8CFU/g dw dominated by Gram-positives with minor instances of Actinobacteria and Gammaproteobacteria. ARISA showed a coherence of bacterial assemblages in different preparation lots of the same year in spite of geographic origin. Enzymaticactivities showed elevated values of β-glucosidase, alkaline phosphatase, chitinase, and esterase. The preparation had no quorum sensing-detectable signal, and no rhizobial nod gene-inducing properties, but displayed a strong auxin-like effect on plants. Enzymatic analyses indicated a bioactive potential in the fertility and nutrient cycling contexts. The IAA activity and microbial degradation products qualify for a possible activity as soil biostimulants.
Of the bacterial species, two dominated 90% of the culture. Half was Bacillus megaterium a plant growth promoting rhizobacteria (PGPR) known to produce Cytokinin. While the other half was Bacillus safensis another PGPR known to produce Auxins.
Cytokinins promote cell division and act in concert with auxins that promote cellular expansion. And, for example, the ratio of auxin to cytokinin in certain plant tissues determines initiation of root versus shoot buds.
Sounds like it should be called PGPR 500.
Great talk, shit audio.
Plant species diversity doesn’t improve soil
The above quote was left as a reply to a comment I’d left on a big ag research and education industry video talking about cover crops ages ago. It still irks me that these people are so ignorant.
Today I read the following study on plant species diversity’s impact on soil ecosystems, albeit in a conservation and restoration context that ends up restoring degraded agricultural lands these people create:
Restoring and managing for more diverse plant communities can improve recovery of belowground biology and functioning in predictable ways. Specifically, we found greater accumulation of roots, more predictable recovery of soil microorganisms (bacteria and fungal biomass), more rapid improvement in soil structure (less compaction), and less nitrogen available for loss from the system in prairie restored and managed for high plant diversity (>30 species) relative to the low diversity (<10 species) grassland plantings. Thus, the hypothesis that biodiversity promotes ecosystem functioning is relevant to large-scale conservation and restoration practices on the landscape.