Microbial pretreatment of biomass: potential for reducing severity of thermochemical biomass pretreatment.

Typical pretreatment requires high-energy (stearn and electricity) and corrosion-resistant, high-pressure reactors. A review of the literature sug­ gests that fungal pretreatment could potentially lower the severity require­ ments of acid, temperature and time. These reductions in severity are also expected to result in less biomass degradation and consequently lower inhibitor concentrations compared to conventional thermochemical pre­ treatment. Furthermore, potential advantages of fungal pretreatment of agricultural residues, such as corn stover, are suggested by its effective­ ness in improving the cellulose digestibility of many types of forage fiber and agricultural wastes. Our preliminary tests show a three- to five-fold improvement in enzymatic cellulose digestibility of corn stover after pre­ treatment with Cyathus stercoreus; and a ten- to IOO-fold reduction in shear force needed to obtain the same shear rate of 3.2 to 7 rev / s, respectively, after pretreatment with Phanerochaete chrysosporium. Index Entries: Microbial pretreatment; fungal pretreatment; corn stover; enzymatic hydrolysis.