Production and statistical optimization of invertase-free exoinulinase from Glutamicibacter arilaitensis using goat dung as ideal feedstock

Abstract

Inulinase is an inulin degrading enzyme that exhibits versatility in disparate bioresource and bioprocess industries. In this study, invertase-free exoinulinase was initially produced from Glutamicibacter arilaitensis strain ALA4 using diversified inexpensive substrates under solid state fermentation. Strain ALA4 revealed maximum production of inulinase using goat dung as quintessential feedstock. Inulinase activity of strain ALA4 was further optimized by one-factor-at-a-time method, followed by response surface methodology, which showed enhanced inulinase activity of 4678.34±34.67 U/g at 96 h using goat dung medium of pH 8.0 with 100% of moisture content. Furthermore, crude inulinase was not only thermo-alkali stable but also exhibited tolerance towards varied metal ions, organic solvents, surfactants, and inhibitors with satisfactory residual activities. Additionally, fructose produced due to the hydrolysis of inulin present in goat dung was analyzed by osazone and HPTLC tests which further confirmed exoinulinase nature of enzyme. In a nutshell, the study evidenced the first report on invertase-free exoinulinase production from G. arilaitensis using goat dung as proficient feedstock and demonstrated its quiescent applications in bioprocessing industries in future.