Study of L-asparaginase production by Streptomyces noursei MTCC 10469, isolated from marine sponge Callyspongia diffusa

L-asparaginase is an anti-neoplastic agent used in the chemotherapy of lymphoblastic leukaemia. The present work deals with production of extra-cellular L-asparaginase from marine actinomycetes, using submerged fermentation. Marine actinomycete Streptomyces associated with marine sponge Callyspongia diffusa was isolated using specific ISP medium. Sponge-associated Streptomyces was characterized by conventional methods, and identified as Streptomyces noursei MTCC 10469. Production of L-asparaginase by submerged fermentation was carried out using medium Tryptone Glucose Yeast extract (TGY) broth. The enzyme was purified to near homogeneity by ammonium sulphate precipitation, dialysis, gel filtration on Sephadex G-100 column, CM Sephadex C-50 and SDS-PAGE. The enzyme was purified at 98.23 folds, and showed a final specific activity of 78.88 IU/mg, with 2.14% yield. SDS-PAGE of the purified enzyme revealed an apparent molecular weight of 102 kDa for it. The optimum pH, temperature and incubation time of L-asparaginase was found to be 8, 50ºC and 35 min, respectively. The study suggests that marine actinomycetes, particularly Streptomyces, may be used as a potential source of L-asparaginase.