Statistical optimization of L-asparaginase production by Cladosporium tenuissimum

Abstract

Background L-asparaginase produced by plant and bacteria can be used in the pharmaceutical and food industry. Unlike the bacterial counterparts, fungal L-asparaginase has more stability, more activity, and less adverse effects. Central composite design (CCD) was used to optimize temperature, pH, incubation time, and carbon-to-nitrogen ratio for L-asparaginase production by Cladosporium tenuissimum via submerged fermentation. CCD reduces the number of tests and time for optimization. Objective To optimize the culture conditions, such as temperature, pH, production time, and the ratio between concentration of carbon and nitrogen sources, for the production of L-asparaginase by isolated C. tenuissimum via submerged fermentation. Materials and methods Primarily, four significant parameters (temperature, pH, incubation period, and carbon-to-nitrogen ratio) were identified that affect the production process of L-asparaginase via submerged fermentation using the modified Czapek Dox medium. CCD was used to optimize the selected parameters concurrently, and their results were compared. Results and conclusions The highest L-asparaginase enzyme activity obtained was 2.6471 U/ml at 37°C, pH 6.2, incubation time 72 h, and 2 : 1 carbon-to-nitrogen ratio. The P value of interaction between every two factors was only significant for the interaction between temperature and incubation period (P<0.0281). The most significant factor was temperature followed by pH (P<0.0154) and carbon-to-nitrogen ratio (P<0.0346). Incubation period has no major effect on the production of L-asparaginase, but it has a quadratic effect (P<0.0001). Our results showed the significant role of culture conditions (temperature, pH, incubation period, and carbon-to-nitrogen ratio) in L-asparaginase production and confirmed the need for optimization.