Studies on novel thermophilic alphaproteobacteria isolated from hot springs in Taiwan

• Main Authors: Silk Yu Lin, 林思妤
• Other Authors: Jhy-Yih Leu
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/13540749106807239442

碩士 === 輔仁大學 === 生命科學系碩士班 === 94 === In this study, the samples of hot springs CL, WR, LGK, DD were serially diluted, spread on modified Thermus medium and further incubated at 50 oC. In total, 12 strains were obtained from 4 hot spring samples. The 16S rDNA sequences of 12 strains were determined, and then analyzed in NCBI database of 12 strains. Five strains NTU-400, NTU-402, NTU-1162, NTU-1290, and NTU-1611 were selected to be representatives for further research, which demonstrated with 93 % ~ 94 % similarity of 16S rDNA sequences to Roseomonas gilardii ATCC49956T. According to the 16S rDNA sequences and morphological, physiological, and biochemical experiments, the isolated strains can be clustered into two groups. The two groups showed 92.5 % ~ 93.4 % similarity of 16S rDNA sequences each other. Group I including experimental strains NTU-400 and NTU-402 showed 94.3 % and 94.2 % similarity to Roseomonas gilardii ATCC49956T respectively and 99.8 % each other. Both strains are Gram-negative, pink-pigmented, cocci and the DNA G＋C contents were 68.6 and 70.2 mol% . Group II including NTU-1162, NTU-1290 and NTU-1611 strains showed 96.8 %, 96.7 % and 96.1 % similarity of 16S rDNA sequences to Roseomonas lacus TH-G33T respectively, and 99.0 % ~ 99.7 % each other. The strains are gram negative, orange-pigmented, rods and the DNA G＋C contents are 60.4, 62.5 and 64.1 mol% . All the isolates have a single polar flagellum, the optimal growth temperature at 30 ~ 50 oC, PH 5 ~ 12 and maximal growth temperature at 55 oC. Oxidase, catalase, alkaline phosphatase and esterase are evidently positive. They are positive in reactions of β - hemolysis. The major compositions of cellular fatty acids are C16:0, C18:0 and C18:1. These isolates were resistant to the Vancomycin (30 μg), Polymyxin (300 U), Colistin (10 μg) and Nalidixic acid (30 μg). According to the morphological, physiological and genetic results, the group I can be classified as a new genus of alphaproteobacteria, while group II can be a new species of genus Roseomonas.