An alkali-tolerant xylanase produced by the newly isolated alkaliphilic Bacillus pumilus from paper mill effluent.
An alkaline active xylanase, XynBYG, was purified from an alkaliphilic Bacillus pumilus BYG, which was newly isolated from paper mill effluent. It had an optimum pH of 8.0-9.0, and showed good stability after incubated at pH 9.0 for 120 min. The optimum temperature for the activity was 50°C, and the enzyme retained below 55% of its original activity for 30 min at 55°C. The gene coding for XynBYG consists of 687 bp and encodes 229 amino acids. Similarity analysis indicated that XynBYG belong to family 11 glycosyl hydrolases. Site-directed mutagenesis was performed to replace five sites (Tyr/Ser) to Arg/Glu and the results demonstrated that the optimum temperature of the mutant Y7 (S39R-T146E) increased 5°C and the half-life of inactivation (T1/2) at 60 and 65°C was 1 h and 25 min, respectively. Thus, it provides a potential xylanase that can meet the harsh conditions in the industrial applications.
Wang
Jing
J
College of Animal Sciences and Technology, Northwest A&F University, 712100, Yangling, People's Republic of China.
Zhang
Wei-wei
WW
Liu
Jin-ni
JN
Cao
Yao-ling
YL
Bai
Xiao-ting
XT
Gong
Yue-sheng
YS
Cen
Pei-lin
PL
Yang
Ming-ming
MM
D000222:Adaptation, Physiological / Q000187:drug effects; D000468:Alkalies / Q000494:pharmacology*; D001407:Bacillus / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification*; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D043364:Endo-1,4-beta Xylanases / Q000096:biosynthesis*; D004795:Enzyme Stability / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial / Q000235:genetics; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007220:Industrial Waste / Q000032:analysis*; D016297:Mutagenesis, Site-Directed; D010209:Paper; D017422:Sequence Analysis, DNA; D013696:Temperature; D014865:Waste Disposal, Fluid
D000468:Alkalies; D007220:Industrial Waste; D043364:Endo-1,4-beta Xylanases