Production of ?-amylase by Bacillus amyloliquefaciens in batch and continuous culture using a defined synthetic medium

Statistical Based Bioprocess Design for Improved Production of Amylase from Halophilic Bacillus sp. H7 Isolated from Marine Water

Amylase (EC 3.2.1.1) enzyme has gained tremendous demand in various industries, including wastewater treatment, bioremediation and nano-biotechnology. This compels the availability of enzyme in greater yields that can be achieved by employing potential amylase-producing cultures and statistical optimization. The use of Plackett-Burman design (PBD) that evaluates various medium components and having two-level factorial designs help to determine the factor and its level to increase the yield of product. In the present work, we are reporting the screening of amylase-producing marine bacterial strain identified as Bacillus sp. H7 by 16S rRNA. The use of two-stage statistical optimization, i.e., PBD and response surface methodology (RSM), using central composite design (CCD) further improved the production of amylase. A 1.31-fold increase in amylase production was evident using a 5.0 L laboratory-scale bioreactor. Statistical optimization gives the exact idea of variables that influence the production of enzymes, and hence, the statistical approach offers the best way to optimize the bioprocess. The high catalytic efficiency (kcat/Km) of amylase from Bacillus sp. H7 on soluble starch was estimated to be 13.73 mL/s/mg.

Purification, characterization, and statistical optimization of a thermostable α-amylase from desert actinobacterium Streptomyces fragilis DA7-7

In this study, preliminary screening revealed that of 134 desert soil actinobacterial isolates, only 43 isolates produced amylase. Among these, an isolate DA7-7, which was identified as Streptomyces fragilis DA7-7, showed a prominent zone of clearance and significant amount of α-amylase production. The pre-optimization studies showed varying physicochemical and nutrients properties of the medium influenced the enzyme production significantly. Consequently, central composite design was employed with the selected variables (pH, temperature, dextrose, and peptone) for α-amylase production. The optimum fermentation conditions were 3.07% dextrose, 1.085% peptone, pH 6.0, and incubation temperature 27.27 °C. The predicted optimum α-amylase activity was 991.82 U/mL/min, which was similar to the experimental amylase activity of 973.5 U/mL/min. The crude α-amylase produced by S. fragilis DA7-7 was purified with ammonium sulfate precipitation, followed by gel filtration chromatography, and the estimated molecular mass was 51 kDa. The purified α-amylase was stable under the following conditions: pH (4-9), temperature (40-80 °C), NaCl (1-4 M), and detergents (1-10 mM). The Km and Vmax values of enzyme were found to be 0.624 mU/mg and 0.836 mg/mL, respectively.

Chicken feathers: a complex substrate for the co-production of alpha-amylase and proteases by B. licheniformis NH1

This study is concerned with the co-production of alkaline proteases and thermostable alpha-amylase by some feather-degrading Bacillus strains: B. mojavensis A21, B. licheniformis NH1, B. subtilis A26, B. amyloliquefaciens An6 and B. pumilus A1. All strains produced both enzymes, except B. pumilus A1, which did not exhibit amylolytic activity. The best enzyme co-production was obtained by the NH1 strain when chicken feathers were used as nitrogen and carbon sources in the fermentation medium. The higher co-production of both enzymes by B. licheniformis NH1 strain was achieved in the presence of 7.5 g/l chicken feathers and 1 g/l yeast extract. Strong catabolic repression on protease and alpha-amylase production was observed with glucose. Addition of 0.5% glucose to the feather medium suppressed enzyme production by B. licheniformis NH1. The growth of B. licheniformis NH1 using chicken feathers as nitrogen and carbon sources resulted in its complete degradation after 24 h of incubation at 37 degrees C. However, maximum protease and amylase activities were attained after 30 h and 48 h, respectively. Proteolytic activity profiles of NH1 enzymatic preparation grown on chicken feather or casein-based medium are different. As far as we know, this is the first contribution towards the co-production of alpha-amylase and proteases using keratinous waste. Strain NH1 shows potential use for biotechnological processes involving keratin hydrolysis and industrial alpha-amylase and proteases co-production. Thus, the utilization of chicken feathers may result in a cost-effective process suitable for large-scale production.

Production and properties of α-amylase fromBacillussp. BKL20

As a result of screening Bacillus sp. strains isolated from different natural substrates, strain BKL20 was identified as a producer of a thermostable alkaline α-amylase. Maximum production of this α-amylase was achieved by optimizing culture conditions. Production of α-amylase seemed to be independent of the presence of starch in the culture medium and was stimulated by the presence of peptone (0.3%, m/v) and yeast extract (0.2%, m/v). The enzyme was thermostable and retained amylolytic activity after 30 min of incubation at 60 and 70 °C. High activity was maintained over a broad pH range, from 6.0 to 11.0, and the enzyme remained active after alkaline incubation for 24 h. Bacillus sp. BKL20 α-amylase was not stimulated by Ca2+or other bivalent metal cations and was not inhibited by EGTA or EDTA at 1–10 mmol/L, suggesting that this α-amylase is a Ca2+-independent enzyme. It also showed good resistance to both oxidizing (H2O2) and denaturating (urea) agents.

A highly thermostable and alkaline amylase from a Bacillus sp. PN5

A highly thermostable alkaline amylase producing Bacillus sp. PN5 was isolated from soil, which yielded 65.23 U mL(-1) of amylase in medium containing (%) 0.6 starch, 0.5 peptone and 0.3 yeast extract at 60 degrees C, pH 7.0 after 60 h of incubation. Maximum amylase activity was at pH 10.0 and 90 degrees C. The enzyme retained 80% activity after 1 h at pH 10.0. It exhibited 65% activity at 105 degrees C and had 100% stability in the temperature range between 80 and 100 degrees C for 1 h. In addition, there was 86.36% stability after 1-h incubation with sodium dodecylsulphate. These properties indicated possible use of this amylase in starch saccharification and detergent formulation.