Optimized chromogenic dyes-based identification and quantitative evaluation of bacterial l-asparaginase with low/no glutaminase activity bioprospected from pristine niches in Indian trans-Himalaya.

Here, we report on the isolation of bacterial isolates from Himalayan niches, which produced extracellular l-asparaginase with low/no glutaminase activity. From the 235 isolates, 85 asparaginase positive bacterial isolates were identified by qualitative screening using optimized chromogenic dyes assay. Optimized concentration of different dyes revealed maximum color visualization in phenol red (0.003%). The diversity analysis of asparaginase positive isolates revealed that (83%) are the most dominant, followed by (12%), (3%), and (2%). Eleven isolates, which represented seven species, one species each of the genus , , , and , were selected for further studies based on highest zone ratio and novel aspects for l-asparaginase production. Of these, five isolates, namely, sp. PCH133, sp. PCH146, sp. PCH182, sp. PCH162, and sp. PCH138, produced l-asparaginase without glutaminase activity after 55 h of growth with the former isolate showing the highest l-asparaginase activity (1.67 U/ml). Interestingly, this is the first report of l-asparaginase production by members of the genera , , and .