Fermentation of Cellulose

Abstract

This study is concerned primarily with two aspects of submerged fermentation of solid cellulose: the effects of foaming and pure oxygen utilization (in place of air) upon growth and enzyme production of the organism T. viride QM9414. Pure oxygen flow rates are varied, and growth and enzyme production data are compared to results obtained during air fermentation runs (with flow rates five times those of pure oxygen for comparison purposes and still to meet oxygen requirements of the organism for growth). At an initial cellulose concentration of 1.0% for all fermentation runs, aeration with pure oxygen resulted in an enhancing effect upon enzyme production rate (about 1.5-2 times as fast as with air). It appeared that better oxygen utilization was associated with the pure oxygen fermentations as indicated by slightly lower average DO levels. This was thought to be attributed to better oxygen mass transfer during the oxygen fermentations, which would favor protein synthesis. Foaming was a problem common to both air and oxygen systems, but more so to air runs, especially during the first J-4 days. It was determined that enzyme was present in the foam, which would account in part for lower levels in solution. Cell autolysis, which favors good enzyme production, occurred at earlier times during the oxygen fermentations, which would also help to explain better enzyme production rates with pure oxygen. Finally, the phenomenon of catabolic repression, characteristic of both glucose and cellobiose, seemed to be evident especially during the earlier stages of both air control runs, which would have inhibited enzyme production during these times.