PRETREATMENT OF CELLULOSIC MATERIALS FOR DIGESTION BY RUMINOCOCCUS ALBUS

Abstract

The effects of chemical pretreatment on cellulose digestion by a cellulolytic anaerobe, Ruminococcus albus, were examined. Pretreatment with H₃PO₄ was the most effective for digestion of crystalline cellulose by R. albus of the four pretreatment methods investigated. The best condition for pretreatment of Avicel with H₃PO₄ was as follows; H₃PO₄ concentration: 85-100 (v/v)%; treatment time: over 5 min; treatment temperature: 0°C at 85 (v/v)% H₃PO₄ or 0-60°C at 95 (v/v)% H₃PO₄; cellulose concentration: 1-3 (w/w)%. Treatment efficiencies did not decrease after five repeated uses of H₃PO₄. For effective digestion of newspaper or rice straw, delignification was essential in addition to swelling with H₃PO₄. For newspaper and rice straw which were cryomilled, delignified and swollen with H₃PO₄, specific cellulose digestion rates by R. albus were 0.081 and 0.099 g cellulose/g dry cells/hr, respectively.