Isolation and characterization of facultatively anaerobic, fermentative bacteria from lagoon of Dongsha Island
| Autor: | Tzu-Yin Chen, 陳姿尹 |
|---|---|
| Rok vydání: | 2017 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 105 Fermentation is the process that microorganisms decompose organic materials and gain energy under anaerobic conditions. Glucose is one of the most abundant organic matters in the marine environment. Many of the marine bacteria may involve in carbon cycling through metabolizing glucose in the seawater. The objectives of this study were to isolate and characterize the glucose-fermenting bacteria from lagoon of Dongsha Island,to analyze the phylogenetic relationships of bacteria in different types of sediments and to investigate the biodiversity of facultatively anaerobic, fermentative bacteria in the lagoon. Most-probable-number (MPN) counts revealed that the facultatively anaerobic, fermentative bacteria in the lagoon sediments ranged from 2.4 x 105 to 2.4 x 107 cells/g wet wt. Higher counting values were obtained in samples from seagrass debris, coral rubble,and the sediments surrounding the rhizosphere of Thalassia hemprichii and Cymodocea rotundata. Forty-two strains of facultatively anaerobic, fermentative bacteria were isolated from the samples. All strains were Gram-negative, and halophilic. All of them grew in 25-30 ℃, pH 6-9, and 1-5 % NaCl. Majority of these strains showed catalase and oxidase activities. Phylogenetic analysis based on 16S rRNA gene sequences revealed that all isolates belonged to class Gammaproteobacteria, which could be further classified as members of the genusCobetia within family Halomonadaceae, the genusNeptunomonas within family Oceanospirillaceae, and thegenera Grimontia, Aliivibrio, andVibriowithin familyVibrionaceae.Among these isolates, 83.3 % (35/42)were classified to be Vibrio species. Strains A4 and A5might be proposed to represent a novel genus and species in the future since they had16S rRNA gene sequence similarity below 92.0 % compared with their most closely relatedspecies. Phylogenetic analysis revealed the potentially new genus bacteria belonged to family Aeromonadaceaeand were named Dongshaea marina tentatively. Additionally,strain B1, H2, and H5 had 16S rRNA gene sequence similarity below 97.3 % in comparison to the type strains of the closestVibrio species.These three strains also might be proposed to be novel Vibrio species in the future.In summary, this study showed that Vibrio was the dominant genus in culturable facultatively anaerobic, fermentative bacteria within most lagoon sediment samples. However, in bulk sediment sample, Aliivibrio and Neptunomonas were the dominant fermentative bacteria. All strains isolated in the study would bepotential participants in fermentation process in lagoon sediment of Dongsha Island. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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