INFLUENCE OF ENVIRONMENTAL-FACTORS ON ENDO-BETA-1,4-GLUCANASE PRODUCTION BY BACILLUS HR68, ISOLATED FROM A ZIMBABWEAN HOT-SPRING

The production of endo-beta-1,4-glucanase by a Bacillus strain isolate d from a hot spring in Zimbabwe was studied in batch culture, chemosta t culture, and carbon dioxide-regulated auxostat (CO2-auxostat). The b acteria produced the enzyme in the presence of excess glucose or sucro se, but not under carbon-limited conditions in a chemostat using miner al medium. There was a specific growth rate dependent linear increase in enzyme production in glucose excess, nitrogen-limited chemostat cul tures. A high specific growth rate of 2.2 h(-1) and a high rate of enz yme production of 362 nkat (mg dry mass . h)(-1) were attained under n utrient rich conditions in the CO2-auxostat. The bacteria had the high est specific growth rate and endo-beta-1,4-glucanase enzyme production at 50 degrees C. The maximum specific growth rate and the rate of enz yme production increased when yeast extract and tryptone were added in increasing amounts to the mineral medium used for cultivation in sepa rate experiments. Increasing the glucose concentration in the CO2-auxo stat cultures increased the rate of enzyme production but did not affe ct the specific growth rate.