Metagenomic and functional analysis of hindgut microbiota of a wood-feeding higher termite

摘要

From the Standpoints of both basic research and biotechnology, there is considerable interest in reaching a dearer understanding of the diversity of biological mechanisms employed during ligno-cellulose degradation. Globally, termites are an extremely success-ful group of wood-degrading organisms and are therefore important both for their roles in carbon turnover in the envir-onment and as potential sources of biochemical catalysts for efforts aimed at converting wood into biofuels. Only recently have data supported any direct role for the symbiotic bacteria in the gut of the termite in cellulose and xylan hydrolysis. Here we use a metagenomic analysis of the bacterial Community resident in the hindgut paunch of a wood-feeding 'higher' Nasutitermes species (which do not contain cellulose-fermenting protozoa) to show the presence of a large, diverse set of bacterial genes for cellulose and xylan hydrolysis. Many of these genes were expressed in vivo or had cellulase activity in vitro, and further analyses implicate spirochete and fibrobacter species in gut lignocellulose degradation. New insights into other important symbiotic functions including H_2 metabolism, CO_2-reductive acetogenesis and N_2 fixation are also provided by this first System-wide gene analysis of a microbial com-munity specialized towards plant lignocellulose degradation. Our results underscore how complex even a 1-μl environment can be.