Mahnaz Nasre Taheri, Gholamhossein Ebrahimipour, Hossein Sadeghi,
Volume 6, Issue 3 (10-2019)
Abstract
Proteases are important industrial enzymes used in different areas of industry, mainly detergent, food and leather industries. In this study, novel alkaline protease-producing bacterium was isolated from Geinarje hot spring and examined for maximum protease activity to be utilized in washing-powder. The isolated bacterium was cultured in mineral salt medium including 2% Skim Milk. Proteolytic activity of supernatant was measured by caseinolytic method. The effects of pH, temperature, SDS, Tween 80 and EDTA on protease stability and activity were investigated. The detergent compatibility of protease was assayed. On the basis of phylogenetic analysis and morphological as well as biochemical tests, the isolate was identified as a new strain of Brevibacillus borstelensis capable of generating extracellular alkaline protease. The generated protease was determined as alkaline metallo-protease having high activity at 60 oC and pH 9. Moreover, the alkaline protease was stable in the presence of SDS, Tween 80 and H2O2. It is compatible with commercial detergents. Finding proteases capable of degrading proteins in extreme environment (i.e. alkaline pH, high temperature and presence of surfactants) is valuable in biotechnological and industrial practices. Therefore, it can be utilized in detergent formulation in the future.
Mahdi Alijanianzadeh, Alireza Jalalvand, Rasoul Khalilzadeh, Maryam Abdolirad,
Volume 9, Issue 4 (12-2022)
Abstract
S-layer proteins of Deinococcus radiodurans are the best self-assemble systems among other proteins that have an essential role in the fabrication of nanowires. Therefore, the purification of these proteins is necessary. The purpose of this research was to optimize the purification of s-layer protein from D. radiodurans with the response surface method. The three factors of SDS concentration, incubation time and mass percent in five levels were considered, and 20 runs were designed by Design-Expert software with a central composite method. Each run includes microbe culture, mass cell preparation, microbe incubation in specific SDS concentration and time and mass percent, separation of the bacteria from detergent with a centrifuge at 5000g, sedimentation of s-layer proteins from detergent solution with a centrifuge at 20000g, determination of protein concentration, and protein purity by Bradford and SDS-PAGE methods, respectively. Finally, the data obtained were analyzed. Analysis of the results demonstrated that at the 95% confidence level, the effect of the detergent concentration factor on the purified protein percent was more than other factors. The optimization results of factors are 5.64% SDS concentration, 7.33% mass percent, and 3 hours incubation time. At optimized conditions the protein concentration and purity percent were obtained 0.584 mg/ml and 47.61% respectively.
