Production and characterization of thermo-, halo- and solvent-stable esterase from Bacillus mojavensis TH309

Abstract

The use of enzymes in many industrial applications has gained increasing importance in recent years due to their non-toxic, specific, and eco-friendly characteristics. However, two main reasons limiting their use in industry are production costs and instability under harsh conditions. We isolated thermophilic and halo-tolerant/halophilic bacteria from bio-deteriorated plastic waste. Among them, Bacillus mojavensis isolate TH309 exhibited excellent esterase secretion ability. Esterase production on sunflower seed meal increased approximately 20-fold (80.43 U/gds) with optimization of solid state medium using Plackett Burman design and response surface methodology Box Behnken design. The enzyme (BmEST) was purified 7.82-fold using ultrafiltration and anion-exchange techniques. The molecular weight of BmEST was estimated to be 30 kDa. BmEST demonstrated an optimal temperature and pH of 80 degrees C and 8.0, respectively, and was remarkable stable at 60-90 degrees C. BmEST exhibited high activity and stability in the presence of NaCl (5-20%). Furthermore, it was hyper-activated by n-pentane, acetone, hexane, DMSO, methanol, and ethanol. The apparent K-m and V-max values of BmEST were 1.28 mM and 23.88 mu mol/min, respectively, with p-nitrophenol butyrate as a substrate. The enzyme caused a mass loss of poly(epsilon-caprolactone) films of 44% after 12 h hydrolysis. As a result, BmEST, with remarkable functional properties, presents a promising candidate to meet the needs of certain harsh biotechnological applications.