Plant biomass degradation by gut microbiomes: more of the same or something new?

Herbivores retain within their gastrointestinal tract a microbiome that specializes in the rapid hydrolysis and fermentation of lignocellulosic plant biomass. With the emergence of high-throughput DNA sequencing technologies and related 'omics' approaches, along with demands to better utilize lignocellulose materials as a feedstock for secondgeneration biofuels, these gut microbiomes are thought to be a potential source of novel biotechnologies relevant to meeting these needs. This review provides an insight into the new findings that have arisen from the (meta)genomic analysis of specialist cellulolytic bacteria and gut microbiomes of herbivorous insects, ruminants, native Australian marsupials, and other obligate herbivores. In addition to there being more of the same in terms of cellulases and cellulosomes, there also appears to be something 'new' in terms of the compositional and functional attributes of the plant cell wall deconstruction systems employed by these bacteria. However, future dissection and capture of useful biotechnologies via metagenomics will need more than the production of data using next generation sequencing technologies.