Screening of Microbial Isolates for the Fermentative Production of L-Asparaginase in Submerged Fermentation
L-asparaginase is a well-recognized amino acid degrading enzyme exhibiting antineoplastic activity. It is desirable to opt for attempts leading to the discovery of new L-asparaginase producer that is serologically different from the previously reported ones, but exhibiting similar therapeutic effects. Twenty six microbial cultures including three microbial consortia were tested for their ability to produce L-asparaginase. Pure cultures of locally isolated microbes, a few commercially used microbes and three microbial consortia (gut consortia of earthworm and termites) were examined qualitatively and quantitatively for their ability to produce L-asparaginase. Seven of the 26 cultures including the sea water isolate tested, gave consistent positive results in qualitative assay and hence they were taken up for further quantitative studies. The cell free fermentation broth of the sea water isolate gave 0.710U /mL/ hour of L-asparaginase activity in starch casein broth. For a local isolate of S. cerevisiae (BIT -74) in yeast developmental broth, the same was found to be 0.884U /mL/hour. In M9 medium, when the yeast isolate was grown in the presence of asparagine, enzyme activity increases by a factor of 20%. The sea water isolates gave consistent enzyme activity in starch casein broth till 160 hrs and the pace of enzyme titer accumulation was high in asparagine incorporated M9 broth. It is clearly indicated through the findings in this study that many of the regular microbial cultures have the ability to produce L-asparaginase. A couple of isolates possess the ability to produce a significant amount of L-asparaginase enzyme. Presence of asparagine in M9 medium induced the enzyme yield.
Kesavapillai Balakrishnan, Aiswarya Nair and Rahul Kumar