Cellulosic biomass in plant cell walls consists of a complex assemblage of cellulose, hemicellulose, lignin and other recalcitrant materials. While cellulose and hemicellulose polymers can be enzymatically decomposed to fermentable six- and five-carbon sugars, respectively, lignin is much more difficult to decompose and has traditionally been viewed as a waste product. White rot fungi such as Phanerochaete chrysosporium are unique in their ability to synthesize enzymes that degrade lignin and to grow on the degradation products. When combined with its ability to produce cellulases and the availability of an annotated genome, this lignin degrading capability makes P. chrysosporium a promising microbial platform for converting a broad range of biomass feedstocks to liquid fuels and other chemicals. Unlike conventional microbes that are efficiently grown in suspension cultures, previous studies have shown that solid-state fermentation provides a superior growth environment that more closely mimics the natural environment of P. chrysosporium.

Through collaboration with Dr. Anthony Ferrante (PSI Inc.), we are combining solid-state fermentation and metabolic modeling to optimize P. chrysosporium conversion of lignocellulosic biomass to jet fuel precursors. Our current research is focused on fully instrumenting our custom made solid-state fermenter to allow the collection of high quality data, characterizing P. chrysosporium physiology on soluble substrates in suspension culture to guide future solid-state fermentation experiments, and developing a draft genome-scale model of P. chrysosporium metabolism to guide ongoing cellular engineering efforts aimed at increasing jet fuel precursor synthesis rates. Our longer term goal is to utilize the metabolic model for in silico metabolic engineering and model-based bioreactor optimization to maximize precursor production.

Funding: Navy

Student: Swati Khanna (1st year post-doctoral student)

Collaborator: Dr. Anthony Ferrante (PSI Inc.)

Schematic representation of solid-state fermenter for lignocellulose conversion to jet fuel precursors.