Novel extracellular hyper acidophil and thermostable α-amylase fromMicrococcussp.NS 211

An amylopullulanase (ApuNP1) from Geobacillus thermoleovorans NP1: biochemical characterization and its potential industrial applications

An amylopullulanase was produced by Geobacillus thermoleovorans NP1. The optimum enzyme production occurred at 45°C and pH 7.0 (12 hr). NP1 amylopullulanase (ApuNP1) exhibited the maximal activity at 50°C and pH 6.0 and was stable between 30-50°C, and pH 3.0-12.0 for 24 hr. The enzyme showed two bands with molecular weights of 112 and 107 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The amylopullulanase retained 100% of its activity in the presence of 10 mM of Ca²⁺, Ba²⁺, Zn²⁺, Mg²⁺, Cu²⁺, EDTA, and PMSF. While the enzyme showed resistance to 5% of TritonX-100, Tween 20, and Tween 80, the activity was inhibited by 5% β-mercaptoethanol and H₂O₂. While the hydrolysis products of pullulan were maltose, maltotriose, and maltodextrin, the starch was hydrolyzed to maltose, maltotriose, and maltodextrin units. This shows that NP1 pullulanase is a type II pullulanase (amylopullulanase). After the liquefaction assay, 12% glucose content was measured with a refractometer in the presence of 20% starch. According to the wash performance tests, the mixture of ApuNP1 and 1% detergent removed almost all of the stains. This novel thermo-acidic amylopullulanase has a potency to be used in detergent, starch, food, baking, textile, and cosmetic industries.

Isolation and characterization of a cold-active, alkaline, detergent stable α-amylase from a novel bacterium Bacillus subtilis N8

A cold-active alkaline amylase producer Bacillus subtilis N8 was isolated from soil samples. Amylase synthesis optimally occurred at 15°C and pH 10.0 on agar plates containing starch. The molecular weight of the enzyme was found to be 205 kDa by performing SDS-PAGE. While the enzyme exhibited the highest activity at 25°C and pH 8.0, it was highly stable in alkaline media (pH 8.0-12.0) and retained 96% of its original activity at low temperatures (10-40°C) for 24 hr. While the amylase activity increased in the presence of β-mercaptoethanol (103%); Ba²⁺, Ca²⁺, Na⁺, Zn²⁺, Mn²⁺, H₂O₂, and Triton X-100 slightly inhibited the activity. The enzyme showed resistance to some denaturants: such as SDS, EDTA, and urea (52, 65, and 42%, respectively). N8 α-amylase displayed the maximum remaining activity of 56% with 3% NaCl. The major final products of starch were glucose, maltose, and maltose-derived oligosaccharides. This novel cold-active α-amylase has the potential to be used in the industries of detergent and food, bioremediation process and production of prebiotics.

Cloning, Purification and Characterization of a Highly Thermostable Amylase Gene of Thermotoga petrophila into Escherichia coli

A putative α-amylase gene of Thermotoga petrophila was cloned and expressed in Escherichia coli BL21 (DE3) using pET-21a (+), as an expression vector. The growth conditions were optimized for maximal expression of the α-amylase using various parameters, such as pH, temperature, time of induction and addition of an inducer. The optimum temperature and pH for the maximum expression of α-amylase were 22 °C and 7.0 pH units, respectively. Purification of the recombinant enzyme was carried out by heat treatment method, followed by ion exchange chromatography with 34.6-fold purification having specific activity of 126.31 U mg(-1) and a recovery of 56.25%. Molecular weight of the purified α-amylase, 70 kDa, was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme was stable at 100 °C temperature and at pH of 7.0. The enzyme activity was increased in the presence of metal ions especially Ca(+2) and decreased in the presence of EDTA indicating that the α-amylase was a metalloenzyme. However, addition of 1% Tween 20, Tween 80 and β-mercaptoethanol constrained the enzyme activity to 87, 96 and 89%, respectively. No considerable effect of organic solvents (ethanol, methanol, isopropanol, acetone and n-butanol) was observed on enzyme activity. With soluble starch as a substrate, the enzyme activity under optimized conditions was 73.8 U mg(-1). The α-amylase enzyme was active to hydrolyse starch forming maltose.

Exhaustive study of the novel hyper alkalophil, thermostable, and chelator resistant metalloprotease

Our newly discovered metalloprotease, designated as ALP NS12 was selected using gelatin agar plates with incubation at 100 °C. Subcloning of the fragments in to pUC118 to make E. coli HB101 (pPEMP01NS) with following two-step chromatography using diethylaminoethyl sepharose (DEAE-sepharose) and Sephadex G-100 columns to purify 97-kDa expressed enzyme was performed. Although activity of immobilized ALP NS12 on glass surface was established at temperatures between 70 and 120 °C and pH ranges 4.0-13.0, the optimum temperature and pH were achieved at 100 °C and 11.0, respectively. Enhancement of enzyme activity was obtained in the presence of 5 mM MnCl2 (91 %), CaCl2 (357 %), FeCl2 (175 %), MgCl2 (94 %), ZnCl2 (412 %), NiCl (86 %), NaCl (239 %), and Na-sulfate (81 %) while inhibition was observed with EDTA (5 mM), PMSF (3 mM), urea (8 M), and SDS (1 %) at 65, 37, 33, and 42 %, respectively. Consequently, the enzyme was well analyzed using crystallography and protein modeling. ALP NS12 can be applied in industrial processes at extreme temperatures and under highly basic conditions, chelators, and detergents.