Statistical optimization of thermo-alkali stable xylanase production from Bacillus tequilensis strain ARMATI

Background: Xylanase from bacteria finds use in prebleaching process and bioconversion of lignocelluloses into feedstocks. The xylanolytic enzyme brings about the hydrolysis of complex biomolecules into simple monomer units. This study aims to optimize the cellulase-free xylanase production and cell biomass of Bacillus tequilensis strain ARMATI using response surface methodology (RSM). Results: Statistical screening of medium constituents and the physical factors affecting xylanase and biomass yield of the isolate were optimized by RSM using central composite design at N = 30, namely 30 experimental runs with 4 independent variables. The central composite design showed 3.7 fold and 1.5 fold increased xylanase production and biomass yield of the isolate respectively compared to 'one factor at a time approach',inthe presence of the basal medium containing birchwood xylan (1.5% w/v) and yeast extract (1% w/v), incubated at 40°C for 24 h. Analysis of variance (ANOVA) revealed high coefficient of determination (R2)of0.9978 and 0.9906 for the respective responses at significant level (p < 0.05). The crude xylanase obtained from the isolate showed stability at high temperature (60°C) and alkaline condition (pH 9) up to 4 h of incubation. Conclusions: The cellulase-free xylanase showed an alkali-tolerant and thermo-stable property with potentially applicable nature at industrial scale. This statistical approach established a major contribution in enzyme production from the isolate by optimizing independent factors and represents a first reference on the enhanced production of thermo-alkali stable cellulase-free xylanase from B. tequilensis.

Bioconversion of agro-industrial wastes for the production of fibrinolytic enzyme from Bacillus halodurans IND18: Purification and biochemical characterization

Background: Agro-wastes were used for the production of fibrinolytic enzyme in solid-state fermentation. The process parameters were optimized to enhance the production of fibrinolytic enzyme from Bacillus halodurans IND18 by statistical approach. The fibrinolytic enzyme was purified, and the properties were studied. Results: A two-level full factorial design was used to screen the significant factors. The factors such as moisture, pH, and peptone were significantly affected enzyme production and these three factors were selected for further optimization using central composite design. The optimum medium for fibrinolytic enzyme production was wheat bran medium containing 1% peptone and 80% moisture with pH 8.32. Under these optimized conditions, the production of fibrinolytic enzyme was found to be 6851 U/g. The fibrinolytic enzyme was purified by 3.6-fold with 1275 U/mg specific activity. The molecular mass of fibrinolytic enzyme was determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis, and it was observed as 29 kDa. The fibrinolytic enzyme depicted an optimal pH of 9.0 and was stable at a range of pH from 8.0 to 10.0. The optimal temperature was 60°C and was stable up to 50°C. This enzyme activated plasminogen and also degraded the fibrin net of blood clot, which suggested its potential as an effective thrombolytic agent. Conclusions: Wheat bran was found to be an effective substrate for the production of fibrinolytic enzyme. The purified fibrinolytic enzyme degraded fibrin clot. The fibrinolytic enzyme could be useful to make as an effective thrombolytic agent.