TRUE CELLULASE PRODUCTION BY CLOSTRIDIUM-THERMOCELLUM GROWN ON DIFFERENT CARBON-SOURCES

Clostridium thermocellum produced different levels of true cellulase ( ''Avicelase'') depending on the carbon source used for growth. In defi ned medium with fructose, the cellulase titer was seven times higher t han with cells growing on cellobiose and four times higher than cells growing with glucose. During the lag phase on fructose, the difference s were even more dramatic, i.e. 60 times higher than in cells growing on cellobiose and 40 times that of cells lagging or growing in glucose . In an attempt to detect factors that might contribute to these diffe rences, we considered intracellular ATP, chemical potential (DELTApH), electrical potential (DELTAY), proton motive force (DELTAp), growth r ate, and rates of uptake of inorganic phosphate and sugars. We noted a direct correlation between cellulase production and intracellular ATP levels and an inverse relationship of cellulase production with DELTA Y and DELTAp values. It thus appears that cellulase is best produced b y cells high in ATP and low in Dp and its electrical component DY. The re was no obvious relationship between the cellulase titer and the oth er parameters. Although the physiological significance of such correla tions is unknown, the data suggest tha E further investigation is warr anted.