Journal of Environmental Biology

Studies on L-asparaginase enzyme of actinomycetes isolated from estuarine fishes

Maloy Kumar Sahu¹, K. Sivakumar*¹, E. Poorani², T. Thangaradjou¹ and L. Kannan^1,3

¹Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai-608 502, India

²Kongunadu Arts and Science College, Coimbatore-614 729, India

³Thiruvalluvar University, Vellore-632 004, India

(Received: March 19, 2005 ; Revised received: July 28, 2005 ; Accepted: August 10, 2005)

Abstract: Actinomycetes were isolated from different organs viz. skin, gills and gut contents of three species of fishes viz. Mugil cephalus (Linnaeus, 1758), Chanos chanos (Forskal, 1775) and Etroplus suratensis (Bloch, 1780) using three different media from the Vellar estuary, situated along the southeast coast of India. Among the three fishes, M. cephalus harboured highest number of actinomycetes population in all the three body parts examined followed by C. chanos and E. suratensis. Out of the three body parts of all fishes, gut contents had highest actinomycetes population followed by gills and skin. Among the three media used for isolation of actinomycetes, Kuster’s agar medium was found to be suitable than the starch casein agar and glucose asparagine agar media. Out of the 40 strains isolated, only six strains (LA-2, LA-8, LA-15, LA-20, LA-29 and LA-35) showed significant L-asparagianse activity and were taken up for further studies. Impact of various physical and chemical factors such as pH, temperature, sodium chloride concentration, carbon sources and amino acids on the growth of actinomycetes and L-asparaginase activity was also studied. Optimum growth and enzyme activity was noticed under pH 7 to 8, temperature 37 ⁰C, 1-2% sodium chloride concentration, sucrose as carbon source and without any amino acids. Analysis of the cell components of the isolated strains has revealed the wall type - I (the wall type- I is typical for the genus Streptomyces) and the strains were micromorphologically similar to the genus Streptomyces. Hence, the morphological, physiological and biochemical along with the micromorphological results obtained for the L-asparaginase producing strains were compared and the strains were tentatively identified as Streptomyces aureofasciculus (LA-2), S. chattanoogenesis (LA-8), S. hawaiiensis (LA-15), S. orientalis (LA-20), S. canus (LA-29) and S. olivoviridis (LA-35).

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