Production of a bacterial extracellular L-glutaminase possessing high antioxidant capability

Abstract

Background and objectives L-glutaminase has utmost practical importance in many fields, such as medicine, pharmacy, and some industries as an effective antioxidant, anticancer, flavor enhancer, and used as an analytical reagent in the determination of glutamate and glutamine. The objective of the present article was to formulate the production medium and to pinpoint the proper growth conditions for the most potent microorganism producing highly active glutaminase enzyme. The general properties of the crude enzyme preparation were determined to detect the proper conditions for enzyme activity. Under the specified conditions, the capabilities of the crude L-glutaminase preparation for antimicrobial and antioxidant activities were investigated. Materials and methods A total of 12 recommended microbial strains were screened for highly active L-glutaminase enzyme production. Factors influencing the production of L-glutaminase enzyme were optimized, and the important properties of the crude enzyme were pinpointed. Finally, biological activities of the crude enzyme were investigated as a preliminary index for the validity of the partially purified L-glutaminase form for medical applications. Results and conclusion Among all tested microorganisms, Bacillus subtilis NRRL 1315 was the most potent producer for L-glutaminase enzyme. The maximum glutaminase production was obtained after 48 h of incubation on a rotary shaker (150 rpm) with the medium containing 5 g/l glucose, 0.1 g/l sodium nitrate, and 10 g/l L-glutamine at 37°C and pH 7.5. The important properties of the crude L-glutaminase were duly pinpointed as follows: optimum enzyme protein concentration and substrate concentration were 2 mg/ml and 40 mM, respectively, and optimum reaction pH and temperature were 7.5 and 37°C, respectively. Under the specified conditions, the crude enzyme exhibited considerable 2, 2′-diphenyl-1-picrylhydrazyl radical scavenging activity.