Gene cloning, expression, and characterization of two endo-xylanases from Bacillus velezensis and Streptomyces rochei, and their application in xylooligosaccharide production

Jing Zhang; Yan Qin; Qingyan Wang; Sijia Liu; Jin Zhou; Baoxiang He; Xinquan Liang; Liang Xian; Junhua Wu

doi:10.3389/fmicb.2023.1292726

Gene cloning, expression, and characterization of two endo-xylanases from Bacillus velezensis and Streptomyces rochei, and their application in xylooligosaccharide production

Front Microbiol. 2023 Dec 19:14:1292726. doi: 10.3389/fmicb.2023.1292726. eCollection 2023.

Authors

Jing Zhang¹, Yan Qin², Qingyan Wang², Sijia Liu¹, Jin Zhou¹, Baoxiang He¹, Xinquan Liang¹, Liang Xian², Junhua Wu²

Affiliations

¹ College of Light Industry and Food Engineering, Guangxi University, Nanning, China.
² National Key Laboratory of Non-food Biomass Energy Technology, Guangxi Academy of Sciences, Nanning, China.

Abstract

Endo-xylanase hydrolyzing xylan in cellulosic residues releasing xylobiose as the major product at neutral pH are desirable in the substitute sweeteners industry. In this study, two endo-xylanases were obtained from Streptomyces rochei and Bacillus velezensis. SrocXyn10 showed the highest identity of 77.22%, with a reported endo-xylanase. The optimum reaction temperature and pH of rSrocXyn10-Ec were pH 7.0 and 60°C, with remarkable stability at 45°C or pHs ranging from 4.5 to 11.0. rBvelXyn11-Ec was most active at pH 6.0 and 50°C, and was stable at 35°C or pH 3.5 to 10.5. Both rSrocXyn10-Ec and rBvelXyn11-Ec showed specific enzyme activities on wheat arabinoxylan (685.83 ± 13.82 and 2809.89 ± 21.26 U/mg, respectively), with no enzyme activity on non-xylan substrates. The Vmax of rSrocXyn10-Ec and rBvelXyn11-Ec were 467.86 U mg^-1 and 3067.68 U mg^-1, respectively. The determined Km values of rSrocXyn10-Ec and rBvelXyn11-Ec were 3.08 g L^-1 and 1.45 g L^-1, respectively. The predominant product of the hydrolysis of alkaline extracts from bagasse, corncob, and bamboo by rSrocXyn10-Ec and rBvelXyn11-Ec were xylooligosaccharides. Interestingly, the xylobiose content in hydrolysates by rSrocXyn10-Ec was approximately 80%, which is higher than most reported endo-xylanases. rSrocXyn10-Ec and rBvelXyn11-Ec could be excellent candidates to produce xylooligosaccharides at neutral/near-neutral pHs. rSrocXyn10-Ec also has potential value in the production of xylobiose as a substitute sweetener.

Keywords: bamboo; corncob; endo-xylanase; sugarcane bagasse; xylobiose; xylooligosaccharide.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. Guangxi Science and Technology Plan Project (Guike AB21220022), the Central Guidance Fund for Local Scientific and Technological Development Project (Guike ZY23055011), Guangxi Science and Technology Major Project (Guike AA22096023).