中国吐鲁番两株产木聚糖酶的极端耐碱Bacillus halodurans的分类鉴定(英文)

Isolation and identification of two xylanase_producing extremely alkali_tolerant strains of Bacillus halodurans from Turpan in China

通过生理生化实验、16S rDNA序列分析和同源性杂交，将分离到的XJU-1和XJU-80菌种进行了分类鉴定。XJU-1和XJU-80具有较宽的pH生长范围（分别是pH4．5～12．6和pH3．8～12．6），其G＋C mol％含量分别是40．5mol％和42．2mol％。16S rDNA序列分析和DNA-DNA同源杂交结果表明，XJU-1和XJU-80与Bacillus halodurans C-125和Bacillus halodurans DSM497^T具有较高的同源性（99％）；两者之间也具有85％的相关性，但其与Bacillus halodurans C-125和Bacillus halodurans DSM497^T分别具有81．3％和71．5％的相关性。基于以上结果，将两株分离菌株分类为Bacillus halodurans的两个新品系。

Bacillus halodurans XJU-1 and XJU-80 were characterized in terms of physiological and biochemical characteristics, and 16S rDNA sequence homology and DNA-DNA hybridization analysis. The two isolates can grow in nutrient broth at a broad range of pH values from 4.5 to 12.6 for XJU- 1 and from 3.8 to 12.8 for XJU-80, respectively. And the optimum temperature of growth were around 39℃ and 42℃, respectively. Phylogenetic analysis of the two strains based on comparison of 16S rRNA sequence revealed that they are closely related to Bacillus halodurans C-125 and DSM49^Twith 99% identity. DNA-DNA hybridization showed that the highest levels of DNA-DNA relatedness were found between the two strains （85%） and the B. halodurans type strains （81.3% and 71.5% ）, respectively. Moreover, the G ＋ C content of the genomic DNA was 40.5 mol% for XJU-1 and 42.2 mol% for XJU-80.Our results demonstrate that strains XJU-1 and XJU-80 should be classified as two new members of the species B. halodurans.