Screening of xylanase producing Bacillus species and optimization of xylanase process parameters in submerged fermentation

Abstract

One of the main process inputs in the microbial enzyme, an environment friendly and an extraordinary catalyst, production is characteristics of the microorganism. This study aimed to screen newly isolated Bacillus species for the xylanase production potentiality and investigate crucial parameters that affect the xylanase producing process. Bacteria samples were isolated from potential agricultural and food sources such as soil, wheat bran, and sourdough. Eight xylanase producing isolates showed 99% homology to Bacillus species according to 16S rRNA sequence analysis. Isolate A67 has been found the best xylanase producer isolate and identified as Bacillus halotolerans DSM 8802. Incubation temperature, initial medium pH, and agitation speed parameters were optimized by RSM in the shake flask scale. The optimum xylanase production points were found as 30 °C, pH 8, and 127.27 rpm under submerged fermentation conditions. Xylanase activity was obtained experimentally as 23.47 U/mL resulting 4.21-fold increase with the statistical optimization. R2 and predicted R2 values that reflects the significance of the designed model were calculated as 0.9964 and 0.9674, respectively. Incubation temperature has been concluded as the most important parameter that affects the xylanase activity for isolate A67. As it has low incubation temperature demand, metabolizes xylan polymer as a carbon source and most of the Bacillus species do not produce any toxin, isolate A67 could have potential for the usage of the lignocellulosic biomass added media to make fermentation cost effective in food-grade xylanase production process.