Plant biomass represents a vast and renewable source of energy. However harnessing this energy requires breaking down tough lignin and cellulose cell walls. In nature certain microbes can deconstruct biomass into simple sugars by secreting combinations of enzymes. Two organisms that utilize cellulose are Clostridium thermocellum and Trichoderma reesei. Both are well-known and relied upon in the biomass field. Yet research suggests another microorganism of the Streptomyces bacteria group may hold previously unrecognized potential. Streptomyces species ActE is associated with a destructive wood-eating wasp and could represent a new source of cellulose-degrading enzymes. UW–Madison researchers have derived preparations from ActE secretions that highly degrade lignocellulose. The bacteria can be obtained from Sirex noctilio wasps and grown on a substrate containing mostly cellulose hemicelluloses xylan wood or non-wood biomass and chitin. The substrate may be pretreated for better results. The ActE are grown aerobically to maximize the secretion of both oxidative and hydrolytic enzymes capable of rapid deconstruction of matter. The secretions can be purified and added directly to biomass slurry. Applications: 1) Biofuels 2) Converting cellulosic biomass to cellobiose and xylose 3) Converting paper waste to readily fermentable saccharides 4) Animal feeds with easier digestibility 5) Processing shellfish chitin into soluble constituents 6) Converting mannan-enriched material to mannose and mannobiose 7) Commercial food processing
1) Secretions provide all the enzymes needed for breaking down cellulose to cellobiose in soluble form. 2) Proteins can be purified directly from secretions without tags or recombinant means. 3) ActE is able to grow in a wide range of pH. 4) Bacteria can be genetically modified to achieve proteolysis-proof secretions.