Potential of thermophilic amylolytic bacteria for growth in unconventional media: Potato peels

Extremozymes have gained high level of popularity for their industrial relevance. In this regard four thermophilic bacterial isolates were isolated from hot spring Chakwal in Pakistan. All the strains were screened for amylolytic activity by producing zone of clearance on starch agar plates. The bacterial isolates were cultivated employing potato peels as major energy source. All the four bacterial strains were Gram positive, motile, endospore formers and were positive for catalase and oxidase tests. Phylogenetic analysis based on 16S rRNA sequences confirmed that all the strains were belonged to the Bacillus licheniformis with 98–99% similarity under Accession numbers KF424263, KF424264, KF424265, and KF424266 for KA2, KA5, KA6, and KA9, respectively. The pH, temperature, oxygen requirement, and inocula size of the medium were optimized, which could yield amylase up to 0.61 U while growing in potato peels based media. Besides being thermostable, the enzymes have a working pH range of 5–9. The isolate KA2 showed maximum threefold purification, and percentage yield was estimated to be 93.06% as compared to crude enzyme. They yielded enough protein suggesting their potential in industrial applications in unconventional and economical substrate.

Practical applications

Amylases produced in this study could be utilized in starch hydrolysis for the production bioethanol and can be employed in different industries like food, paper, and detergent for various purposes. In addition, production of efficient amylases resolves the waste management problem of agro‐industrial waste of potato peels.