Impact of Carbon and Nitrogen Sources on L-Asparaginase Production by Isolated Bacillus circulans (MTCC 8574): Application of Saturated Plackett-Burman Design

M. Hymavathi, T. Sathish, P. Brahmaiah and R. S. Prakasham

Abstract
The present work aimed to study the impact of different carbon and nitrogen sources on the effective production of L-asparaginase by isolated Bacillus circulans using Plackett-Burman design (PBD). Among carbon sources; lactose, galactose, starch, sucrose, maltose, arabinose and among nitrogen sources; proline, tryptone, sodium glutamate, corn steep liquor, beef extract, ammonium chloride, yeast extract at selected concentration produced a maximum of 105 and 164 U mL–1 L-asparaginase enzyme, respectively. Initial analysis of L-asparaginase data with different carbon and nitrogen sources as per PBD did not reveal standardized effects as well as ‘p’ and ‘t’ values. Regression coefficient and t-values were calculated by subjecting the experimental data to statistical analysis after pooling the least two nutrient components into error. Among selected 26 components, xylose, galactose, yeast extract and proline denoted least significance, while glucose, mannose, ammonium chloride and ammonium sulphate showed maximum significance on enzyme production. Saturated PBD can be effectively utilized for analysis of the data by pooling the least significant factors based on the effects on metabolite/product/enzyme production. Ammonium chloride and glucose were observed to be the most significant carbon and nitrogen sources, respectively in L-asparaginase production in this bacterial strain. The presented approach is highly useful in bioprocess optimization procedure where all selected parameters show little degree of freedom and subsequent significant factors.

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Keywords
L-asparaginase, Bacillus circulans, saturated Plackett-Burman design, optimisation