[Objective] The purpose of this research is to isolate cold-adapted bacteria producing p-galactosidase from permafrost sediments of the bottom layer of the Glacier No. 1 in the Tianshan Mountains, China. Physiological test and phylogenetic analysis were undertaken to expand our knowledge on diversity of psycrotrophic and psycrophlic bacteria. [Methods] By using lactose as the main carbon source and X-Cal as chromogenic agent in the medium, cold-adapted strains producing p-galactosidase were detected. Taxonomic identity and genetic diversity of strains isolated were determined by spatial 16S rRNA gene sequences and rep-PCR fingerprint. In addition, we analyzed the phonotypic differences between strains showing high similarity of 16S rRNA gene sequences, including the optimum growth temperature, salt tolerance, ability to use carbon source and antibiotic resistance spectra. [ Results] Of the total 90 cold-adapted bacterial strains isolated, we found 25 stains with p-galactosidase activity, 76% of which were Gram-positive bacteria. According to growth temperature range, 80% of strains producing p-galactosidase were identified as psychrophilic bacteria, 20% as psychrotrophs. Phylogeneticlly, the p-galactosidase-producing bacterial isolates fell in four groups: subclasses α、β and γ of Proteobacteria, and Firmicutes phylum. [Conclusion] The results enrich our knowledge on the phylogenetic and physiological diversity of cold-adapted strains producing p-galactosidase in cold environments.%[目的]通过对天山1号冰川底部沉积层冻土中细菌的分离和产β-半乳糖苷酶低温菌株的筛选,了解天山冻土微生物的物种多样性,并对产β-半乳糖苷酶低温菌株的系统发育和生理多样性进行分析.[方法]以乳糖为主要碳源,X-Gal为显色剂,分离筛选出产低温β-半乳糖苷酶菌株.对细菌常规生理生化实验、最适生长温度、耐盐性、药物敏感性进行测定.根据16S rRNA基因序列初步确定产β-半乳糖苷酶低温菌种的系统进化地位,并采用BOX-PCR指纹图谱技术对16S rRNA基因高度同源性的菌株进一步区分.[结果]分离到90株可培养低温菌中25株可产β-半乳糖苷酶,其中76％为革兰氏阳性菌.依据生长温度,产酶菌株80％为嗜冷菌,20％为耐冷菌.在系统发育上,产酶菌株隶属于4个类群,其中肠球菌属(Enterococcus)占26％,短波单胞菌属(Brevundimonas)占22％,假单胞菌属(Pseudomonas)占13％.[结论]天山1号冰川底部沉积层冻土中产β-半乳糖苷酶的低温细菌具有比较丰富的物种和生理多样性.
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