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Microbial Diversity Analysis Of Saline Soil In Northwest China And The Polyphasic Taxonmy Study Of Strains Z-2 And R-8

Posted on:2017-03-01Degree:MasterType:Thesis
Country:ChinaCandidate:T Y WangFull Text:PDF
GTID:2370330623454705Subject:Biology
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The paper introduced the progress of the microbial taxonomy and the study of the genus Kocuria and Bacillus.Isolation for culturable microorganisms in the soil samples collected from Qinghai Province and Ningxia Province were studied,and the strains isolated from the samples were researched using 16S rRNA gene sequence.The investigation of soil microbial diversity and the polyphasic taxonomic study were done as well.In this paper,we firstly used different selective mediums to isolate the culturabale microorganisms in the soil samples.86 resprensentative strains were classified into 19genera,12 familea and three phyla.In Northwest China,phylogenetic analysis based on 16S rRNA gene sequences revealed that the culturable microorganisms are rich in the saline soil.At the same time,we got numbers of halophilic and alkaliphilic microorgannisms.For example,Halobacillus,Bacillus,Pseudomonas,Micrococcus and Streptomyces.The genus Bacillus is the predominant genus.The 16S rRNA gene sequence similarities of two stains designed Z-2 and R-8 to their most closely related species were 98.41%and 98.17%.As a result,the two strains were estimated as new species and subjected to polyphasic studies.A novel Gram-stain-negative,designated as strain Z-2,was isolated from a soil sample collected from Qinghai Province,China.Strain Z-2 formed lemon yellow colonies and grew at temperatures of 20-37C?optimum 28-30C?,at pH 5.0-9.0?optimum pH7.0?and in the presence of 0-7%?w/v?NaCl?optimum 2.0%?.The predominant ubiquinone was MK-8?H2??67.6%?,MK-7?8.9%?and Mk-9?H2??8.3%?.The genomic DNA G+C content was 67.23 mol%.The level of DNA-DNA relatedness values between strain and the closest related specie Kocuria sediminis FS-11T was25.37%.A novel Gram-stain-negative,designated as strain R-8,was isolated from a soil sample collected from Ningxia Province,China.The cells of the strain were srod-shaped with spore in the middle.The colour of colony was orange or nude.Growth at temperatures of 2-37C?optimum 28-30C?,at pH 5.0-10.0?optimum pH7.5-8.0?and in the presence of 0-15%?w/v?NaCl?optimum 3.0%?.The polar lipids were identified as diphosphatidylglycerol?DPG?,phosphatidylglycerol?PG?,phosphatidylethanolamine?PE?.The major cellular fatty acids were iso-C15:0?34.1%?,anteiso-C15:0?16.9%?and C16:1?7c alcohol?10.8%?.The genomic DNA G+C content was 39.78 mol%,and the predominant ubiquinone was MK-7.The level of DNA-DNA relatedness values between strain and the closest related specie Bacillus haikouensis C-89Twas 22.62%.Based on the results of morphological characteristics,physiological and biochemical characteristics,chemical analysis and molecular systematics study,it was proved that the two strains represented novel species.The name of the strain Z-2 was Kocuria citrenus sp.nov;The name of the strain R-8 was Bacillus carnea sp.nov.
Keywords/Search Tags:Kocuria, Bacillus, polyphasic taxonomy, new species
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