Isolation and optimization of glutaminase-free L-asparaginase enzyme producing Serratia marcescens isolated from natural sources

L-asparaginase enzyme is known as one of the best antineoplastic drugs. Since the available commercial asparaginases are from bacterial sources, the aim of this study was to identify and isolate the L-asparaginase- producing bacteria from natural sources.
Asparaginase- producing bacterial strains were isolated from various natural sources. The primary isolation was performed on nutrient agar and asparagine dextrose salts (ADS) agar medium, supplemented with phenol red. Asparaginase- producing colonies with pink color zone were selected for enzyme activity study, and identification using biochemical and molecular tests. Enzyme activity was determined using Nessler’s method. Some factors such as carbon, nitrogen source, and pH were examined to optimize enzyme production process.
Among 133 isolates, the strain isolated from chicken fat exhibited high glutaminase-free L-asparaginase enzyme activity (8.92 U/mg). The selected isolate was identified as Serratia marcescens strain 100 and was registered with accession number KX821734 in NCBI GenBank. The optimal enzyme-producing conditions were as follows: 1.5% (w/v) maltose as a carbon source, 1 % (w/v) ammonium sulfate as the nitrogen source, and initial pH of 6.8.
Considering the use of L-asparaginase enzyme in various pharmaceutical fields, this strain could be a suitable option for industrial production of the enzyme after further clinical studies.