Amylase Production from Thermophilic Bacillus sp. BCC 021-50 Isolated from a Marine Environment

Altaf Simair,Muhammad Bhutto,Imrana Khushk,Abdul Qureshi,Khalil Ansari,Changrui Lu,Haider Chaudhry

doi:10.3390/fermentation3020025

Abstract

The high cost of fermentation media is one of the technical barriers in amylase production from microbial sources. Amylase is used in several industrial processes or industries, for example, in the food industry, the saccharification of starchy materials, and in the detergent and textile industry. In this study, marine microorganisms were isolated to identify unique amylase-producing microbes in starch agar medium. More than 50 bacterial strains with positive amylase activity, isolated from marine water and soil, were screened for amylase production in starch agar medium. Bacillus sp. BCC 021-50 was found to be the best amylase-producing strain in starch agar medium and under submerged fermentation conditions. Next, fermentation conditions were optimized for bacterial growth and enzyme production. The highest amylase concentration of 5211 U/mL was obtained after 36 h of incubation at 50 °C, pH 8.0, using 20 g/L molasses as an energy source and 10 g/L peptone as a nitrogen source. From an application perspective, crude amylase was characterized in terms of temperature and pH. Maximum amylase activity was noted at 70 °C and pH 7.50. However, our results show clear advantages for enzyme stability in alkaline pH, high-temperature, and stability in the presence of surfactant, oxidizing, and bleaching agents. This research contributes towards the development of an economical amylase production process using agro-industrial residues.

Highlights

Amyloglucosidase enzymes are involved in the hydrolysis of starchy materials into oligosaccharides and, into simple glucose units [1]
Fermentation medium cost is one of the important factors in microbial enzyme production and utilization of agro-industrial waste can play a vital role in the reduction
Our results show the thermophilic nature of the newly-isolated strain and growth was fermentable sugars could be converted into biochemical end products

Summary

Introduction

Amyloglucosidase enzymes are involved in the hydrolysis of starchy materials into oligosaccharides and, into simple glucose units [1]. Amylases are of three types, including α-amylase that hydrolyzes α-1,4 bonds and bypasses branched linkages, β-amylase that breaks down α-1,4 and cannot bypass α-1,6 branch linkages and produces maltose as a product, and γ-amylase (glucoamylase) attacks the substrate from the non-reducing end, and hydrolyzes α-1,4 and α-1,6 linkages, releasing monosaccharides as the end product [2]. Amylases are applied in several industrial processes, including saccharification of starchy materials, pharmaceuticals, food, and detergent and textile industries [3,4]. Amylases are produced from all sources of life (plants, animals, and microorganisms) and the demand of production is continuously increasing due to the wide range of industrial applications. Microbial sources are exploited for several industrially-important bioproducts.

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