Statistical optimization of amylase production from Bacillus amyloliquefaciens using agro-industrial waste (mango peels) under submerged fermentation by response surface methodology.

Abstract

The current study aimed to optimize the amylase producing strain using agro-industrial waste under submerged fermentation. Of six bacterial strains, five gave positive results for amylase production but Bacillus amyloliquefaciens was selected due to highest enzyme production. The medium components were selected using Plackett-Burman design (PBD) while concentration of medium components was determined using the central composite design (CCD) of response surface methodology (RSM). The maximum enzyme production was obtained from mango peels (1.25 %), sodium chloride (0.15 %), potassium nitrate (0.06 %), and magnesium sulfate (0.03 %). It was observed that B. amyloliquefaciens produce maximum amylase at 45 °C, pH 5, and 2 % inoculum size over 24-h incubation period. Furthermore, partial characterization revealed best enzyme activity at 9 pH, 50 °C, 1 % substrate concentration, and 30 min of incubation. Besides, amylase was found more stable at 6 pH and 60 ᴼC. In the presence of metal ions, the enzyme activity decreased by Cu⁺² (5 mM) and found maximum in Ca⁺² (1 mM). With the increase in concentration of inhibitors, the amylase activity of ethylenediaminetetraacetic acid (EDTA) and 1, 10-phenanthroline decreases. Among organic solvents, surfactants, and oxidizing agents maximum activity was observed for sodium dodecylsulphate (SDS) and hydrogen peroxide (H₂O₂). These findings highlight the potential of B. amyloliquefaciens as a promising candidate for sustainable and cost-effective industrial amylase production using agro-industrial waste and can be further explored for scale-up studies.