Biochemical studies and biological activities on L-glutaminase from rhizosphere soil Streptomyces rochei SAH2_CWMSG

Abstract

Background and objective L-glutaminase (L-GLUNase) is a potential anticancer enzyme that hydrolyzes amide bond of L-glutamine to give glutamate and ammonium ion. It is used as an antioxidant, a flavor enhancing agent and a biosensor for glutamine level measurement. The aim was to produce L-GLUNase in high yield from a promising local Streptomyces isolate for many pharmaceutical applications. Materials and methods A total of 20 Streptomyces isolates for their capacity of L-GLUNase production were screened. A potent L-GLUNase producer, SAH2_CWMSG isolate, was identified by phenotypic and phylogenetic analysis. L-GLUNase was purified using ammonium sulfate followed by gel filtration on Sephadex G-100. The purified L-GLUNase was characterized, and its application as an antimicrobial, anticancer, and antioxidant agent was investigated. Results and conclusion The phylogenetic analysis of SAH2_CWMSG strain confirmed that the SAH2_CWMSG strain was most similar to Streptomyces rochei (99%). It produced L-GLUNase activity of 58 U/ml under shake flask submerged fermentation. The purified L-GLUNase has the molecular weight of 55 kDa and Km and Vmax value of 1.314 mmol/l and 95.24 μ Me/min, respectively. Of the various physiochemical parameters tested, pH 7.5 and temperature 40°C were optimal for the enzyme activity. On the contrary, 10 mmol/l of Mn+2 showed a slight increase in L-GLUNase activity. A promising Streptomyces sp. fully identified as S. rochei SAH2_CWMSG (Gen Bank ID: KU720627) is an efficient source of L-GLUNase production. Therefore, it can be potentially used as enzyme supplement, which has many industrial and pharmaceutical applications.