Lignocellulose degradation at the holobiont level: teamwork in a keystone soil invertebrate

Abstract

BackgroundWoodlice are recognized as keystone species in terrestrial ecosystems due to their role in the decomposition of organic matter. Thus, they contribute to lignocellulose degradation and nutrient cycling in the environment together with other macroarthropods. Lignocellulose is the main component of plants and is composed of cellulose, lignin and hemicellulose. Its digestion requires the action of multiple Carbohydrate-Active enZymes (called CAZymes), typically acting together as a cocktail with complementary, synergistic activities and modes of action. Some invertebrates express a few endogenous lignocellulose-degrading enzymes but in most species, an efficient degradation and digestion of lignocellulose can only be achieved through mutualistic associations with endosymbionts. Similar to termites, it has been suspected that several bacterial symbionts may be involved in lignocellulose degradation in terrestrial isopods, by completing the CAZyme repertoire of their hosts.ResultsTo test this hypothesis, host transcriptomic and microbiome shotgun metagenomic datasets were obtained and investigated from the pill bug Armadillidium vulgare. Many genes of bacterial and archaeal origin coding for CAZymes were identified in the metagenomes of several host tissues and the gut content of specimens from both laboratory lineages and a natural population of A. vulgare. Some of them may be involved in the degradation of cellulose, hemicellulose, and lignin. Reconstructing a lignocellulose-degrading microbial community based on the prokaryotic taxa contributing relevant CAZymes revealed two taxonomically distinct but functionally redundant microbial communities depending on host origin. In parallel, endogenous CAZymes were identified from the transcriptome of the host and their expression in digestive tissues was demonstrated by RT-qPCR, demonstrating a complementary enzyme repertoire for lignocellulose degradation from both the host and the microbiome in A. vulgare.ConclusionsOur results provide new insights into the role of the microbiome in the evolution of terrestrial isopods and their adaptive radiation in terrestrial habitats.Electronic supplementary materialThe online version of this article (10.1186/s40168-018-0536-y) contains supplementary material, which is available to authorized users.

Characterisation of the gut microbial community of rhesus macaques in high-altitude environments

“…There is increasing evidence that the gut microbial community of animals is involved in a wide range of processes in the host, including health, grow and development as well as behaviour; it can even affect the nervous system by secreting metabolites [1][2][3][4][5][6][7][8][9][10][11]. These microbes can also assist in energy uptake and metabolism [12,13]. Previous research has demonstrated that ruminants depend heavily on gut microbiota to digest fibre in the rumen and use products such as short-chain fatty acids (SCFAs) to meet their energy needs [14,15].…”

Predation impacts late but not early community assembly in model marine biofilms

“…The organic carbon within wood in the form of lignocellulose is accessible to mixotrophic and heterotrophic lignocellulose degraders (i.e. Proteobacteria and Bacteroidetes 51,52 ), thereby the organic carbon could act as an environmental filter. Inert substrates (i.e.…”

Characterization of gut microbial community of rhesus macaques under the high-altitude extreme environments

“…These microbiotas can also assist in the whole-body energy harvest [12]. For example, previous research has demonstrated ruminants depend heavily on gut microbiota to digest fiber in rumen, and panda without a rumen also relys on it's microbiome to degrade hemicellulose and starch in bamboo to provide themselves with energy [13][14][15][16]. The functions of gut microbiota are mainly determined by their composition which is affected by many factors of the host, such as genetic background, health condition, environmental differences, and even social behavior [17][18][19][20][21][22][23][24].…”