Symbiotic digestion of lignocellulose in termite guts

Abstract

Their ability to degrade lignocellulose gives termites an important place in the carbon cycle. This ability relies on their partnership with a diverse community of bacterial, archaeal and eukaryotic gut symbionts, which break down the plant fibre and ferment the products to acetate and variable amounts of methane, with hydrogen as a central intermediate. In addition, termites rely on the biosynthetic capacities of their gut microbiota as a nutritional resource. The mineralization of humus components in the guts of soil-feeding species also contributes to nitrogen cycling in tropical soils. Lastly, the high efficiency of their minute intestinal bioreactors makes termites promising models for the industrial conversion of lignocellulose into microbial products and the production of biofuels.

Acetogenesis from H2plus CO2and nitrogen fixation by an endosymbiotic spirochete of a termite-gut cellulolytic protist

“…The gut microbial community is responsible for the utilization of nutritionally unbalanced and recalcitrant woody cellulose (6,8). Owing to this ability, termites are a keystone of global carbon cycles, are economically detrimental as pests to timber constructions, and as such are expected to be useful in the application of producing biofuel from cellulosic biomass (5,6,8). However, the gut community comprises unique and diverse species, which are mostly yet-uncharacterized due to our historical inability to culture them in the laboratory.…”

“…In the gut of termites, there are various examples of species-specific symbiotic associations between protists (single-cell eukaryotes) and bacteria, and most, if not all, have cospeciated (1)(2)(3)(4)(5)(6). The social behavior of termites has promoted the stable and sustained vertical inheritance of gut microbes between termite generations, which may be advantageous for the emergence and development of these symbiotic associations in the gut community (7).…”

“…The social behavior of termites has promoted the stable and sustained vertical inheritance of gut microbes between termite generations, which may be advantageous for the emergence and development of these symbiotic associations in the gut community (7). The gut microbial community is responsible for the utilization of nutritionally unbalanced and recalcitrant woody cellulose (6,8). Owing to this ability, termites are a keystone of global carbon cycles, are economically detrimental as pests to timber constructions, and as such are expected to be useful in the application of producing biofuel from cellulosic biomass (5,6,8).…”

“…The protists phagocytose ingested wood particles and almost completely decompose and ferment the cellulose to produce acetate, H 2 , and CO 2 (6,8). The host termite uses the produced acetate as a major carbon and energy source.…”

GC×GC-TOFMS for the Analysis of Metabolites Produced by Termites (Reticulitermes flavipes) Bred on Different Carbon Sources

“…These technologies offer the possibility to improve the screening for new enzymes and to study the system as a whole. This is important to enhance the understanding of the termite-microbiota symbiotic association [10], with the need to reproduce their efficient lignocellulolytic system at a larger scale [11]. Metabolomics is the study of small molecule profiles related to biochemical processes.…”