期刊
APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
卷 84, 期 6, 页码 1107-1115出版社
SPRINGER
DOI: 10.1007/s00253-009-2056-y
关键词
Xylanase; XynA; Cold-active; Salt-tolerant; Glaciecola mesophila; Marine; Xylan
资金
- Hi-Tech Research and Development program of China [2007AA091504, 2007AA091903]
- COMRA Program [DYXM-115-02-2-6]
- Doctoral Program of Higher Education [20060422053]
Although a lot of xylanases are studied, only a few xylanases from marine microorganisms have been reported. A new xylanase gene, xynA, was cloned from marine bacterium Glaciecola mesophila KMM 241. Gene xynA contains 1,272 bp and encodes a 423-amino acid xylanase precursor. The recombinant xylanase, XynA, expressed in Escherichia coli BL21 is a monomer with a molecular mass of 43 kDa. Among the characterized xylanases, XynA shares the highest identity (46%) to the xylanase from Flavobacterium sp. strain MSY2. The optimum pH and temperature for XynA is 7.0 and 30 A degrees C. XynA retains 23% activity and 27% catalytic efficiency at 4 A degrees C. XynA has low thermostability, remaining 20% activity after 60-min incubation at 30 A degrees C. Its apparent melting temperature (T (m)) is 44.5 A degrees C. These results indicate that XynA is a cold-active xylanase. XynA shows a high level of salt-tolerance, with the highest activity at 0.5 M NaCl and retaining 90% activity in 2.5 M NaCl. It may be the first salt-tolerant xylanase reported. XynA is a strict endo-beta-1,4-xylanase with a demand of at least four sugar moieties for effective cleavage. It efficiently hydrolyzes xylo-oligosaccharides and xylan into xylobiose and xylotriose without producing xylose, suggesting its potential in xylo-oligosaccharides production.
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