FACTORS AFFECTING UREOLYTIC ACTIVITIES OF PENICILLIUM-WAKSMANII ISOLATED FROM SEWAGE-SLUDGE

Twenty one fungal isolates belonging to 7 genera were screened for ure olytic activity. A Penicillium waksmanii isolate was found to be the m ost potent and was selected for further study. No ammonia-nitrogen was detected in P. waksmanii cultures either urea-free or containing up t o Ig urea per L. The maximum extracellular urease production was recor ded at a urea concentration of 15 g/L. It peaked after 6 d of incubati on at 25 degrees C when the initial pH of the glucose-peptone broth wa s adjusted to 6. On the other hand, the highest fungus biomass was det ected at a concentration of 2 g urea per L after 4 d of incubation at 35 degrees C when the pH of the medium was 8. The intracellular urease activity (measured in cell-free extract) was the highest at 12 mg ure a per mt after 75-min incubation at 25 degrees C at pH 8. Incubation t emperature of 25 degrees C favored both urease production and activity .