Achieving complete breakdown of plant biomass for energy conversion in industrialized bioreactors remains a complex challenge, but new research shows that termite fungus farmers solved this problem more than 30 million years ago. The new insight reveals that the great success of termite farmers as plant decomposers is due to division of labor between a fungus breaking down complex plant components and gut bacteria contributing enzymes for final digestion.
Fungus-farming termites are dominant plant decomposers in (sub)tropical Sub-Saharan Africa and Southeast Asia, where they in some areas decompose up to 90% of all dead plant material. They achieve near-complete plant decomposition through intricate multi-stage cooperation between the Termitomyces fungi and gut bacteria, with the termites managing these symbionts by providing gut compartments and nest infrastructure. Researchers at the Centre for Social Evolution, Department of Biology, University of Copenhagen and Beijing Genomics Institute (BGI, China) discovered this by analyzing plant decomposition genes in the first genome sequencing of a fungus-farming termite and its fungal crop, and bacterial gut communities.
Termites manage their fungus farm in a highly structured way. Older termite workers collect plant material and bring it to the nest. Younger workers eat the plant material together with Termitomyces fungalspores, and this plant-spore mix is defecated as a new layer of fungus garden. Within the garden, Termitomyces rapidly grows on the plant substrate until it is utilized, after which older termites consume the fungus garden. By then, nearly all organic matter has been broken down.
“While we have so far focused on the fungus that feeds the termites, it is now clear that termite gut bacteria play a major role in giving the symbiosis its high efficiency,” says Associate Professor Michael Poulsen, who spearheaded the work. “But it took a massive effort of sequencing the genome of the termite itself, its fungus, and several gut metagenomics to analyze the enzymes involved in plant decomposition,” adds Assistant Professor Guojie Zhang, who made the genome sequencing happen at BGI Shenzhen.
And, of course, it all just sort of happened without any intelligence whatsoever, right?
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