Microbial ecology of an insect gut system as a source of new biocatalysts, enzymes, and antimicrobials

Nature has developed efficient biological systems for extracting energy from plant biomass to fuel microorganisms and animals by effectively deconstructing lignocellulose. Biological systems are the proof-of-concept of what can be physically achieved and these processes can be harnessed for the production of bioenergy sustainably from renewable lignocellulosic biomass. Nature-inspired processes for efficient lignocellulose deconstruction are being examined in detail in several insect systems, including Tipula abdominalis-the aquatic cranefly. T. abdominalis is ubiquitous in riparian aquatic environments, and its larvae are primary shredders of detritus (leaf litter) in streams.  The hindgut of T. abdominalis larvae hosts a dense and diverse community of microorganisms that participate in satisfying the nutritional requirements and fitness of the larvae.  Maceration of biomass substrates reduce particle size and pretreatment occurs in the alkaline midgut where proteolysis degrades complexed proteins making polysaccharide polymers more accessible. In the neutral pH hindgut, bacterial enzymes refine plant polymers into monomeric units. Released sugars are then converted by bacteria to fermentation products, which can be transported across the gut to the hemolymph to support larval energy and growth requirements. Microorganisms isolated from the T. abdominalis larval hindgut included a novel genus and species, Klugiella xanthotipulae, and a multiple enzyme producing Paenibacillus amylolyticus. A genomic library from P. amylolyticus 27C64 was screened for various enzyme activities useful in biomass conversions and a novel pectate lyase with unusual activity on both polygalacturonate and highly methylated pectin was discovered. P. amylolyticus is also a novel source of secreted antimicrobials. The genome has also been recently sequenced.