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Termites "extended phenotype"

A curious idea of the "extended phenotype" (genes can manipulate their environment!) is interestingly shown in the new publication about the interaction of termites with the microbial community of mounds. Termites regulate the environment with hydrogen emissions.

An extended phenotype is the effect of an organism's genes on the environment. The main idea of the extended phenotype was proposed by Dawkins in 1982.

American scientists showed that termites control microbial composition and biogeochemical cycling in their mounds through their emissions of hydrogen. These emissions drive remarkable enrichments of mound bacteria that use hydrogen to drive aerobic respiration and sometimes carbon fixation. Such mound communities efficiently consume all termite-produced hydrogen and even mediate atmospheric uptake, while termite-produced methane escapes to the atmosphere. 

The most dominant bacteria in the soil can subsist on atmospheric hydrogen, but levels of this gas are insufficient to sustain hydrogenotrophic growth. Interesting is that bacteria residing within soil-derived termite mounds are exposed to high fluxes of H2 due to fermentative production within termite guts. Based on metagenomic data, scientists showed that hydrogenase genes are significantly enriched in mounds compared to surrounding soils.

Moreover, experiments shown that high- and low-affinity H2-oxidizing bacteria efficiently consumed all termite-derived H2 emissions and served as net sinks of atmospheric H2. 
Interesting observation is that, while methane is produced at similar rates to H2 by termites, mounds contained few methanotrophs and were net sources of methane. 

PNAS July 27, 2021 118 (30) e2102625118; https://doi.org/10.1073/pnas.2102625118

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