BIOCONVERSION OF CELLULOSE TO ACETATE WITH PURE CULTURES OF RUMINOCOCCUS-ALBUS AND A HYDROGEN-USING ACETOGEN

Bioconversion of cellulose to acetate was accomplished with cocultures of two organisms. One was the cellulolytic species Ruminococcus albus . It ferments crystalline cellulose (Avicel) to acetate, ethanol, CO2, and H-2. The other organism (HA) obtains energy for growth by using H -2 to reduce CO2 to acetate, HA is a gram-negative coccobacillus that was isolated from horse feces. Coculture of R. albus with HA in batch or continuous culture alters the fermentation products formed from cry stalline cellulose by the ruminococcus via interspecies H, transfer. T he major product of the fermentation by R. albus and HA coculture is a cetate. High concentrations of acetate (333 mM) were obtained when bat ch cocultures grown on 5% cellulose were neutralized with Ca(OH)(2). C ontinuous cocultures grown at retention times of 2 and 3.1 days produc ed 109 and 102 mM acetate, respectively, when fed 1% cellulose with ut ilization of 84% of the substrate.