Oral Presentation Australian Microbial Ecology 2019

Termite mounds are biofilters for termite-produced methane and hydrogen (#5)

Eleonora Chiri 1 , Philipp A Nauer 1 2 , Chris Greening 1 , Stefan K Arndt 2
  1. School of Biological Sciences, Monash University, Clayton, VIC, Australia
  2. School of Ecosystem and Forest Sciences, The University of Melbourne, Burnley, VIC, Australia

It is well-established that hydrogen (H2) and methane (CH4) are produced within the anoxic environment of termite hindguts as a result of microbial lignocellulose digestion and methanogenesis. Termites have been found to emit these gases at vastly different rates, depending on feeding groups and species. In contrast, surprisingly little is known about H2 and CH4 turnover from the prospective of the oxic environment of mounds and nests that termites live in. Here we present initial results of a comprehensive study on H2 and CH4 turnover in termite mounds of Northern Australia. We employed a suite of field- and laboratory-based techniques to quantify H2 and CH4 oxidation and identify the responsible microbial communities in mounds of two termite species with different mound architectures and representing the dominant feeding habits. Mounds appeared to be a sink for atmospheric H2 and a source for CH4. However, CH4 emissions were mitigated by microbial CH4 oxidation. Remarkably, both methanotrophic and hydrogenotrophic communities were able to utilize a vast range of substrate concentration, spanning from the percent range to sub-atmospheric (part per million). While bacterial communities appeared to be evenly distributed among different mound locations (core and periphery), the methanotrophic community was concentrated in the core and differed according to the mound-dwelling termite species. The hydrogenotrophic communities appeared to be highly active, with varying activity according to mound locations. In conclusion, our results suggest that mound-associated microbial communities mitigate emissions of the greenhouse gas CH4 and influence atmospheric H2 cycling.