True cellulase production by Clostridium thermocellum grown on different carbon sources

• Published in: Biotechnology letters Vol. 15; no. 6; pp. 641 - 646
• Main Authors: NOCHUR, S. V, ROBERTS, M. F, DEMAIN, A. L
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer 01.06.1993
• Subjects: Biological and medical sciences; Biotechnology; Clostridium thermocellum; Enzyme engineering; Fermentation; Fundamental and applied biological sciences. Psychology; Methods. Procedures. Technologies; Production of selected enzymes; Culture medium; Electric potential; Growth rate; Enzyme; Clostridiales; Environmental factor; Glucose; Motive force; Fructose; Enzymatic activity; Cellobiose; Clostridium thermocellum; Medium effect; Clostridiaceae; Production; Microorganism culture; pH; Bacteria; ATP
• ISSN: 0141-5492; 1573-6776
• DOI: 10.1007/BF00138556

Clostridium thermocellum produced different levels of true cellulase ("Avicelase") depending on the carbon source used for growth. In defined medium with fructose, the cellulase titer was seven times higher than with cells growing on cellobiose and four times higher than cells growing with glucose. During the lag phase on fructose, the differences 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 differences, we considered intracellular ATP, chemical potential ( Delta pH), electrical potential ( Delta Y), proton motive force ( Delta p), growth rate, 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 Delta p values. It thus appears that cellulase is best produced by cells high in ATP and low in Dp and its electrical component DY. There was no obvious relationship between the cellulase titer and the other parameters. Although the physiological significance of such correlations is unknown, the data suggest that further investigation is warranted.