Citrus peel influences the production of an extracellular naringinase by Staphylococcus xylosus MAK2 in a stirred tank reactor

摘要

Staphylococcus xylosus MAK2, Gram-positive coccus, a nonpathogenic member of the coagulase-negative Staphylococcus family was isolated from soil and used to produce naringinase in a stirred tank reactor. An initial medium at pH 5.5 and a cultivation temperature of 30°C was found to be optimal for enzyme production. The addition of Ca+2 caused stimulation of enzyme activity. The effect of various physico-chemical parameters, such as pH, temperature, agitation, and inducer concentration was studied. The enzyme production was enhanced by the addition of citrus peel powder (CPP) in the optimized medium. A twofold increase in naringinase production was achieved using different technological combinations. The process optimization using technological combinations allowed rapid optimization of large number of variables, which significantly improved enzyme production in a 5-l reactor in 34 h. An increase in sugar concentration (15 g l−1) in the fermentation medium further increased naringinase production (8.9 IU ml−1) in the bioreactor. Thus, availability of naringinase renders it attractive for potential biotechnological applications in citrus processing industry.