A thermohalotolerant and proteinaseresistant en

Authors: Junpei Zhou Qian Wu Rui Zhang Minghe Mo Xianghua Tang Junjun Li Bo Xu Junmei Ding Qian Lu Zunxi Huang

Publish Date: 2014/04/13

Volume: 59, Issue: 5, Pages: 423-431

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Abstract

A glycosyl hydrolase family 10 endoxylanase from Bacillus sp HJ14 was grouped in a separated cluster with another six Bacillus endoxylanases which have not been characterized These Bacillus endoxylanases showed less than 52  amino acid sequence identity with other endoxylanases and far distance with endoxylanases from most microorganisms Signal peptide was not detected in the endoxylanase The endoxylanase was expressed in Escherichia coli BL21 DE3 and the purified recombinant enzyme rXynAHJ14 was characterized rXynAHJ14 was apparent optimal at 625 °C and pH 65 and retained more than 55  of the maximum activity when assayed at 40–75 °C 23  at 20 °C 16  at 85 °C and even 8  at 0 °C Halflives of the enzyme were more than 60 min approximately 25 and 4 min at 70 75 and 80 °C respectively The enzyme exhibited more than 62  xylanase activity and stability at the concentration of 3–30  w/v NaCl No xylanase activity was lost after incubation of the purified rXynAHJ14 with trypsin and proteinase K at 37 °C for 60 min Different components of oligosaccharides were detected in the timecourse hydrolysis of beechwood xylan by the enzyme During the simulated intestinal digestion phase in vitro 115–190 153–190 219–277 and 282–312 μmol/mL reducing sugar were released by the purified rXynAHJ14 from soybean meal wheat bran beechwood xylan and rapeseed meal respectively The endoxylanase might be an alternative for potential applications in the processing of sea food and saline food and in aquaculture as agastric fish feed additiveThis work was supported by the Key Technologies Research and Development Program of China 2013BAD10B01 National Natural Science Foundation of China No 31260215 and Science Research Foundation of Yunnan Provincial Education Committee No 2012Y166 We thank Prof James F Preston from the University of Florida for his kind gifts methylglucuronoxylose methylglucuronoxylobiose methylglucuronoxylotriose and methylglucuronoxylotetraose

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