Production of cellulosic organic acids via synthetic fungal consortia

Abstract

Consolidated bioprocessing (CBP) is a potential breakthrough technology for reducing costs of biochemical production from lignocellulosic biomass. Production of cellulase enzymes, saccharification of lignocellulose, and conversion of the resulting sugars into a chemical of interest occur simultaneously within a single bioreactor. In this study, synthetic fungal consortia composed of the cellulolytic fungus Trichoderma reesei and the production specialist Rhizopus delemar demonstrated conversion of microcrystalline cellulose (MCC) and alkaline pre‐treated corn stover (CS) to fumaric acid in a fully consolidated manner without addition of cellulase enzymes or expensive supplements such as yeast extract. A titer of 6.87 g/L of fumaric acid, representing 0.17 w/w yield, were produced from 40 g/L MCC with a productivity of 31.8 mg/L/hr. In addition, lactic acid was produced from MCC using a fungal consortium with Rhizopus oryzae as the production specialist. These results are proof‐of‐concept demonstration of engineering synthetic microbial consortia for CBP production of naturally occurring biomolecules.Scholz and coworkers developed a consolidated bioprocessing system that supports all of the steps required for conversion of lignocellulosic biomass to two organic acids, including cell growth, cellulase enzyme production, lignocellulose hydrolysis, and organic acid production. This process was achieved in a minimal medium, without supplementation of expensive nutrients, by pairing the cellulolytic specialist Trichoderma reesei and a furmaric acid or lactic acid producing fungal specialist into a functional synthetic consortium.