t The present study was intended to investigate the effect of different physico-chemical
parameters that included pH (3–11), temperature (4–60 C), incubation period (2–8 days) and NaCl
(1–10% w/v) concentration on the growth and cellulase enzyme production of the actinomycete
strain St-1, to optimize its enzyme productivity. The strain St-1 isolated locally from soil sample
and identified as Streptomyces griseorubens at MTCC and Gene Bank, Chandigarh, India (Accession
No. AB184139), showed an optimum growth at pH 7, temperature of 45 C and 6 days of incubation
period. The cellulose hydrolysis by the isolate was also optimum at these parameters when
the maximum level of reducing sugar produced due to filter paper activity was 5.6 mg per mL and
CMC activity was 4.5 mg per mL. The isolate was moderately halophilic, as it was unable to grow
beyond 6% of NaCl (w/v) concentration.