S8: Exploring the use of anaerobic fungal strains (Phylum Neocallimastigomycota) in plant biomass degradation and biofuel production

Anaerobic gut fungi represent a distinct basal fungal phylum (Neocallimastigomycota), and reside in the rumen, hindgut, and feces of ruminant and non-ruminant herbivores. Anaerobic fungi combine the invasiveness and plant biomass degrading capability of fungi, with an anaerobic fermentative mode of metabolism. As such, they are excellent candidate for plant biomass degradation and biofuel production from lignocellulosic biomass. We present genomic and experimental evidence of the plant biomass degradation capability of the anaerobic fungal isolate Orpinomyces sp. strain C1A. Strain C1A, was sequenced using a combination of Illumina, and PacBio SMRT technologies. The large genome (100.95 Mb, 16,347 genes) displayed extremely low G+C content (17.0%), large non-coding intergenic regions (73.1%), proliferation of microsatellite repeats (4.9%), and multiple gene duplications. Analysis of the lignocellulolytic machinery in the C1A genome revealed an extremely rich repertoire, with evidence of horizontal gene acquisition from multiple bacterial lineages. Experimental analysis indicated that strain C1A is a remarkable biomass degrader, capable of simultaneous saccharification and fermentation of the cellulosic and hemicellulosic fractions in multiple untreated grasses and crop residues examined, with the process significantly enhanced by mild pretreatments. This capability, acquired during its separate evolutionary trajectory in the rumen, along with its resilience and invasiveness when compared to prokaryotic anaerobes, render anaerobic fungi promising agents for consolidated bioprocessing schemes in biofuels production.