Goat dung as a feedstock for hyper-production of amylase from Glutamicibacter arilaitensis strain ALA4

Abstract

Background: In modern times, bacteria-associated products; especially enzymes are gaining immense interest among worldwide researchers. Among several enzymes, amylases are of great significance in bioprocess engineering. This investigation was aimed to optimize the amylase production from Glutamicibacter arilaitensis strain ALA4 using goat dung as an inexpensive substrate in solid-state fermentation. Results: Amylase production was initially improved by optimizing physical factors and medium components by one factor at a time method. Two-level full factorial design (25 factorial matrix) was applied to screen the selected variables using first-order polynomial model. Parameters such as incubation temperature, moisture, starch, and yeast extract affected the amylase activity significantly (P < 0.05). Central composite design at N = 30 was further employed to evaluate the optimum levels of these variables by a second-order polynomial equation. Maximal amylase activity of 4572.53 ± 41.71 U/g was estimated in the goat dung medium supplemented with 100% moisture, 1% (w/w) starch, and 1% (w/w) yeast extract, being incubated at 40 °C. The optimized parameters revealed approximately twofold increment in the amylase yield (R2 0.9169) with respect to the original medium. The amylase showed stability at high pH and temperature up to 4 h of incubation with residual activities of 52.32 ± 2.2 and 46.12 ± 3.3%, respectively. Additionally, the enzyme revealed resistant property not only towards various metal ions and organic solvents but also surfactants and inhibitors. Most importantly, the amylases obtained from strain ALA4 depicted remarkable tolerance to commercially available various detergents. Conclusions: This study reports first reference on the hyper-production of amylase from G. arilaitensis using goat dung as the low-cost agro-waste medium. G. arilaitensis strain ALA4 may be utilized for wide spread applications in several bioprocess industries due to the high stability of its amylase towards diversified pH, temperature, solvents, surfactants, and detergents. [Figure not available: see fulltext.].