title: [Phylogenetic and physiological diversity of cold-adapted bacteria producing protease from sediments of the bottom layer of the glacier no. 1 in the Tianshan mountains].
abstract: OBJECTIVE
  We characterized proteolytic bacteria isolates from 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 and ecological distribution of psycrotrophic and psycrophlic bacteria populations.
  
  
  METHODS
  Using the screening media containing skim milk, we screened cold-adapted strains producing protease. Taxonomic identity and genetic variability of strains isolated was determined by partial 16S rRNA gene sequences and repetitive-element PCR fingerprint.
  
  
  RESULTS
  Of the total 125 cold-adapted bacterial isolates, high levels of protease activity were observed from 27 isolates at optimal growth temperatures ranging from 15 to 24 degrees C in plate assay. Among 27 protease-producing strains, only 6 isolates were psychrophilic. The 16S rRNA gene phylogenetic analysis revealed that protease-producing isolates belonged to 5 phyum, namely alpha, beta and gamma of Proteobacteria, Actinobacteria and Cytophaga-Flexibacter-Bacteroides. They are affiliated to the genera Pseudomonas, Polaromonas, Brevundimonas, Rholococces, Cryobacterium, Kocuria, Arthrobacter, Chryseobacterium and Flavobacterium. The populations of the predominant cultivated protease-producing bacteria are the Pseudomonas spp. (40.7%).
  
  
  CONCLUSIONS
  The results enriched our knowledge on the phylogenetic and physiological diversity of cold-adapted strains producing protease in cold environments.
authors.affiliation: Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China. niyqlzu@sina.com
authors.forename: Yongqing
authors.initials: Y
authors.lastname: Ni
authors.forename: Yanling
authors.initials: Y
authors.lastname: Gu
authors.forename: Xuewei
authors.initials: X
authors.lastname: Shi
authors.forename: Xiaoji
authors.initials: X
authors.lastname: Zheng
authors.forename: Liang
authors.initials: L
authors.lastname: Han
authors.forename: Hong
authors.initials: H
authors.lastname: Zhou
authors.forename: Guodong
authors.initials: G
authors.lastname: Cheng
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D044822:Biodiversity; D002681:China; D003080:Cold Temperature; D019015:Geologic Sediments / Q000382:microbiology*; D046448:Ice Cover / Q000382:microbiology*; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny
chemical_list: D001426:Bacterial Proteins; D010447:Peptide Hydrolases