Department of Microbiology, Tehran Science and Research Branch, Islamic Azad University, Tehran, Iran.
Department of Microbiology, College of Basic Science, Islamic Azad University, Tehran North Branch, Tehran, Iran.
Iran J Basic Med Sci. 2014 Nov;17(11):844-53.
This study highlights xylanase overproduction from Bacillus mojavensis via UV mutagenesis and optimization of the production process.
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 wastes was designed with Minitab software for the best overproducer mutant.
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.
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.
本研究通过紫外线诱变和优化生产工艺，从解木聚糖芽孢杆菌中大量生产木聚糖酶。
解木聚糖芽孢杆菌 PTCC 1723 经紫外线辐射。突变体的初步筛选是基于在木聚糖琼脂培养基上与野生菌株相比，菌落的空心区直径/菌落直径比值（H/C 比值）增强。其次，比较突变体和原始菌株的酶产量。使用木质纤维素废料的优化过程使用 Minitab 软件设计，以获得最佳的高产突变体。
与亲本菌株的 H/C 比值 1.6 相比，突变体 17 的 H/C 比值为 3.1。选定的突变体产生 330.56 IU/ml 的木聚糖酶。它比野生菌株产生的 95.73 IU/ml 的木聚糖酶多 3.45 倍。优化结果为 575 IU/ml 的木聚糖酶，以麦麸为最佳碳源，玉米浆为最佳氮源，同时使用天然面包酵母粉，在 pH7 的培养基中，在 37°C 下孵育 48 小时，转速为 230rpm。最佳木聚糖酶活性在 pH7 和 40°C 下测定。酶稳定性模式表明，在 3 小时后，在 pH9 下，它保留了初始活性的 62%。在 70°C 和 80°C 下预孵育 1 小时后，它仍保持初始活性的 66%和 59%。
突变和优化使突变株的酶产量增加了 5.9 倍。此外，这种酶可以归类为耐碱和耐热的木聚糖酶。
