uv mutagenesis for the overproduction of xylanase from bacillus mojavensis ptcc 1723 and optimization of the production condition

objective(s):[p1]  this study highlights xylanase overproduction from bacillus mojavensis via uv mutagenesis and optimization of the production process. materials and methods:bacillus mojavenis ptcc 1723 underwent uv radiation. mutants’ primary screening was based on the enhanced hollow zone diameter/ colony diameter ration (h/c ratios) of the colonies in comparison with the wild strain on xylan agar medium. secondly, enzyme production of mutants was compared with parental strain. optimization process using lignocellulolytic [aga2] wastes was designed with minitab software for the best overproducer mutant. results: h/c ratio of 3.1 was measured in mutant number 17 in comparison with the h/c ratio of the parental strain equal to 1.6. selected mutant produced 330.56 iu/ml xylanase. it was 3.45 times more enzyme than the wild strain with 95.73 iu/ml xylanase. optimization resulted 575 iu/ml xylanase, with wheat bran as the best carbon source, corn steep liquor as the best nitrogen source accompanied with natural bakery yeast powder, in a medium with ph 7, after 48 hr incubation at 37°c, and the shaking rate of 230 rpm. optimum xylanase activity was assayed at ph 7 and 40°c. enzyme stability pattern shows it retains 62% of its initial activity at ph 9 after 3 hr. it also maintains up to 66% and 59% of its initial activity after 1 hr of pre-incubation at 70°c and 80°c. conclusion: mutation and optimization caused 5.9 times more enzyme yield by mutant strain. also this enzyme can be categorized as an alkali-tolerant and thermo-stable xylanase.