Screening and Media Optimization for Enhancing L-asparaginase Production, an Anticancer Agent, from Different Filamentous Fungi in Solid State Fermentation

Abstract

Aim: The aim of present study was to screen new potent fungal isolates and microorganisms possessing extracellular L-asparaginase production capacity. In addition, optimization of cultural and environmental conditions required for enzyme production will be carried out for the highest Lasparaginase producer in solid state fermentation (SSF) technique using agro-industrial residues. Study Design: Screening and physiological studies on the formation of L-asparaginase by Trichoderma viride F2 in order to obtain the optimum cultural and environmental conditions required for enzyme production. Place and Duration of Study: Department of Microbial Chemistry, Genetic Engineering and Biotechnology Division, National Research Centre (NRC), Cairo, Egypt, between July 2013 and June 2015. Methodology: Optimization of physical and nutritional parameters for enzyme production was investigated. Various locally available agro-industrial residues have been screened individually or as mixtures for L-asparaginase production. The combination of Rice husk (RH) with wheat bran Original Research Article Elshafei and El-Ghonemy; BBJ, 9(3): 1-15, 2015; Article no.BBJ.19728 2 (WB) (3:2) proved to be an efficient mixture for enzyme production as it gave the highest enzyme activity (71.87±3.19 U/g-ds) when compared to individual RH (66.71±2.76 U/g-ds) or WB (62.28±2.13 U/g-ds) substrates. Results: Maximal L-asparaginase production (113.43±5.11 U/g-ds) by T. viride F2 was obtained with moisture content of 75%, an inoculums size of 1 x 10 spores/ml and an initial medium pH of 5.0 when incubated at 28oC for four days. Presence of Tween 20 enhanced enzyme production by 1.19 folds. Glucose (1.0%), Casein (1.5%) and MgCl2 (0.05%) were found to be the best carbon, organic nitrogen and ion sources, respectively. Supplementation of the medium with NaNO3 (0.15%) as an inorganic nitrogen source further increased L-asparaginase production. Under these optimized conditions, L-asparaginase production by T. viride F2 was maximum with a yield of 276.5±13.4 U/g-ds in SSF, which was more than 19-fold enhancement in enzyme activity as compared to that obtained in the basal medium (SmF) (14.23±0.87 U/ml). Conclusion: The results suggest that choosing a suitable substrate coupled with optimization of different parameters can improves enzyme production markedly. Moreover, the production of Lasparaginase from a process based on RH and WB as substrates in SSF is economically attractive due to abundant substrates availability in agriculture-based countries with cheaper cost.