Comparative growth potential of thermophilic amylolytic Bacillus sp. on unconventional media food wastes and its industrial application

Abstract

Amylases take part with vital role in industries such as food, fermentation; starch processing, textile and paper etc. Increasing amylases demand, high nutrient expenditure and environmental pollution have forced to utilize agro-industrial residues as a low-cost feedstock for enzyme production. In present study, three soil samples were collected from agro-industrial waste dumping areas in District Faisalabad. Ten thermophilic bacterial isolates were separated at 55 °C on the basis of colonial morphology, three isolates (F6, F11, F17) showed prominent zone of clearance applying iodine test on starch agar plates. Bacterial isolate F-11 showed highest amylase activity with DNS method and molecularly identified through 16S RNA sequencing as Bacillus sp. with Accession number MH917294. Four unconventional food wastes (banana, lemon, mango and potato) pretreated with 0.8% sulphuric acid concentrations taking 1000 g/L weight released the highest sugars contents and phenolic components. Maximum amylase activity i.e. 29.23 mg/ml was achieved in mango waste at, 40 °C, with pH 6.0 and 0.17% nitrogenous source adding 8% inoculum size (2 days old) using Response Surface Methodology (RSM) for optimization. Crude amylase confirmed its efficiency in starch hydrolysis that suggested it as potential candidate for application in starch industries.