L-glutaminase Producing Actinomycetes from Marine Sediments –Selective Isolation, Semi Quantitative Assay and Characterization of Potential Strain

Actinomycetes from terrestrial and marine ecosystems have long been recognized either as organism of academic curiosity and organism of antibiotic producers. L-glutaminase is an enzyme produced by various microorganisms which are currently used for the treatment of leukemia, as flavor enhancer and also as enzyme sensors. Even though L-glutaminase activity was reported in various microorganisms, L-glutaminase from actinomycetes in general and marine actinomycete in particular is very scanty. From the reviewed literature, information on L-glutaminase production from actinomycetes is very scanty. With this view, marine sediment sample was collected from mangrove rhizosphere of Parangipettai coastal area (Lat. 11 o.29ʹ N; Long. 79o.46ʹE). Totally 20 L-glutaminase producing actinomycete strains were isolated by using minimal glutamine agar medium supplemented with substrate 1% L-glutaminase, 0.012% phenol red and 3 % NaCl. All the 20 actinomycete strains were micromorphologically identified as Streptomycetes. L-glutaminase enzyme was produced from all the 20 actinomycete strains by submerged fermentation and tested by semi quantitative assay. Crude L-glutaminase produced from strain P2 produced 38 mm of pink color zone. L-glutaminase produced from strain P2 was purified further by precipitation and dialysis methods. In semi quantitative assay of dialysate showed 45 mm of zone of color change. Optimal condition for L-glutaminase production was determined at pH 7, temperature 30°C and salinity 3.5%. Based on the studied phenotypic characteristics the potential actinomycete strain was identified as Streptomyces olivochromogenes (P2). The selective isolation procedure and semi quantitative assay developed in this present study will be a suitable and best method for therapeutic enzymes in general and L-glutaminase in particular