Optimisation of Media and Cultivation Conditions for Alkaline Protease Production by Alkaliphilic Bacillus halodurans

Crude proteolytic enzyme from Bacillus halodurans BCRC 910501 and its application in leather processing

Enzymes are biological catalysts that exist in all living organisms. Proteases are one of the most important enzymes in the industry; microbial proteases are widely used in the food, textile, detergent, and leather industries. Traditionally, alkaline proteases are used in the leather industry for bating, however, due to environmental issues, there are many investigations for the application of proteolytic enzymes in other operations such as soaking, unhairing, and derma opening up. This study aimed to produce a proteolytic enzyme from B. halodurans BCRC 910501 and apply it to the soaking of salted hide. After cultivation, the crude enzyme was used for further analysis and leather processing. The results showed an enzyme with higher caseinolytic activity compared to keratinolytic activity. A soaking study found that enzyme improves rehydration, non-collagenous protein, and salt removal. Enzymatic soaking affected collagenous proteins more than the control, but did not significantly impact wet-blue leather properties. Using this enzyme in leather processing might be suitable to reduce the duration of soaking and the number of process steps.

Structural-genetic insight and optimization of protease production from a novel strain of Aeromonas veronii CMF, a gut isolate of Chrysomya megacephala

Structural-genetic characterization of protease producing genes and enzymes from microbial sources are seldom appreciated despite having its substantial utilization in protein engineering or genetic manipulation for biotechnological applications. Aeromonas veronii CMF, a mesophilic bacterium isolated from the gut of Chrysomya megacephala, was found to exhibited significant level of protease activity. For the revelation of genetic potential in relation to protease production, whole genome of this organism was sequenced and analysed while structure-function of different protease enzyme was predicated using various in silico analysis. The 4.5 mb CMF genome was found to encompass various types of protease and mostly they are neutral in nature. Enzyme production was highest in an optimum pH and temperature of 6.0 (32.09 ± 1.015 U/ml) and 35ºC (41.65 ± 1.152 U/ml), respectively. Other culture parameters for optimum production of protease were determined to be inoculum size (1%), incubation period (72 h), shaking condition (125 rpm), carbon and nitrogen source [2% lactose (92.21 ± 3.16 U/ml) and 0.5% urea (163.62 ± 4.31 U/ml), respectively] and effect of surfactants [0.02 mg/ml Tween 80 (174.72 ± 4.48 U/ml)]. Furthermore, A. veronii CMF exhibited significant enzyme production like serine protease (15.22 ± 0.563 U/ml), aspartate protease (33.16 ± 0.762 U/ml) and collagenase (17.26 ± 0.626 U/ml). Genomic information and results of physio-biochemical assays indicate its cost-effective potential use in different enzyme-industry.

Production, Purification, and Biochemical Characterization of Thermostable Metallo-Protease from Novel Bacillus alkalitelluris TWI3 Isolated from Tannery Waste

Protease enzymes in tannery industries have enormous applications. Seeking a potential candidate for efficient protease production has emerged in recent years. In our study, we sought to isolate proteolytic bacteria from tannery waste dumping site in Tamilnadu, India. Novel proteolytic Bacillus alkalitelluris TWI3 was isolated and tested for protease production. Maximum protease production was achieved using lactose and skim milk as a carbon and nitrogen source, respectively, and optimum growth temperature was found to be 40 °C at pH 8. Protease enzyme was purified using ammonium sulfate precipitation method and anion exchange chromatography. Diethylaminoethanol (DEAE) column chromatography and Sephadex G-100 chromatography yielded an overall 4.92-fold and 7.19-fold purification, respectively. The 42.6-kDa TWI3 protease was characterized as alkaline metallo-protease and stable up to 60 °C and pH 10. Ca(2+), Mn(2+), and Mg(2+) ions activated the protease, while Hg(2+), Cu(2+), Zn(2+), and Fe(2+) greatly inhibited it. Ethylenediaminetetraacetic acid (EDTA) inhibited TWI3 protease and was activated by Ca(2+), which confirmed that TWI3 protease is a metallo-protease. Moreover, this protease is capable of dehairing goat skin and also removed several cloth stains, which makes it more suitable for various biotechnological applications.