Novel Alkali-Tolerant GH10 Endo-${\beta}$-1,4-Xylanase with Broad Substrate Specificity from Microbacterium trichothecenolyticum HY-17, a Gut Bacterium of the Mole Cricket Gryllotalpa orientalis

• Published in: Journal of microbiology and biotechnology Vol. 24; no. 7; pp. 943 - 953
• Main Authors: Kim, Do Young, Shin, Dong-Ha, Jung, Sora, Kim, Hyangmi, Lee, Jong Suk, Cho, Han-Young, Bae, Kyung Sook, Sung, Chang-Keun, Rhee, Young Ha, Son, Kwang-Hee, Park, Ho-Yong
• Format: Journal Article
• Language: Korean
• Published: 2014
• Subjects: Endo- ${\beta}$-1,4-xylanase; gut bacterium; mole cricket; Microbacterium trichothecenolyticum HY-17; GH10 enzyme
• ISSN: 1017-7825; 1738-8872

The XylH gene (1,167-bp) encoding a novel hemicellulase (41,584 Da) was identified from the genome of Microbacterium trichothecenolyticum HY-17, a gastrointestinal bacterium of Gryllotalpa orientalis. The enzyme consisted of a single catalytic domain, which is 74% identical to that of an endo-${\beta}$-1,4-xylanase (GH10) from Isoptericola variabilis 225. Unlike other endo-${\beta}$-1,4-xylanases from invertebrate-symbiotic bacteria, rXylH was an alkali-tolerant multifunctional enzyme possessing endo-${\beta}$-1,4-xylanase activity together with ${\beta}$-1,3/${\beta}$-1,4-glucanase activity, which exhibited its highest xylanolytic activity at pH 9.0 and 60oC, and was relatively stable within a broad pH range of 5.0-10.0. The susceptibilities of different xylosebased polysaccharides to the XylH were assessed to be as follows: oat spelts xylan > beechwood xylan > birchwood xylan > wheat arabinoxylan. rXylH was also able to readily cleave p-nitrophenyl (pNP) cellobioside and pNP-xylopyranoside, but did not hydrolyze other pNP-sugar derivatives, xylobiose, or hexose-based materials. Enzymatic hydrolysis of birchwood xylan resulted in the product composition of xylobiose (71.2%) and xylotriose (28.8%) as end products.