| Summary: | 碩士 === 國立臺灣大學 === 海洋研究所 === 105 === The aim of this study was isolation and characterization of bacteria in the sediments of Formosa and Penghu submarine canyons and Kaoping slope. The bacterial abundance in the sediments ranged from 5.8 × 103 to 3.7 × 104 cfu/gwet wt. by plate count method. One hundred and eight bacterial strains were isolated from the sediments in the three areas : Formosa submarine canyon (54 strains), Penghu submarine canyon (41 strains) and Kaoping slope (13 strains). The results of the physiological and biochemical tests showed that 29.6 % of the strains were gram negative bacteria and 70.4 % of the strains were gram positive bacteria. All of the strains could grow at pH 6 – 8 and 25 – 30 °C, but all of them could not produce indole; most of the strains (89.8 %) were catalyst positive reactive and most of them (95.4 %) could carry out the nitrate reduction or denitrification under anarobic condtions. Moreover, 89.8 % of the isolated strains could grow at 42 °C. According to the physiological and biochemical characteristics, 13 strains were selected by primary classification for the consequent phylogenetic analysis of the 16S rRNA gene. The sequence results showed that these representivestrains belonged to Marinobacter (1 strain), Pseudoalteromonas (2 strains), Halomonas (2 strains), Halobacillus (1 strain), Staphylococcus (1 strain), Fictibacillus (1 strain), Lysinibacillus (1 strain) and Bacillus (4 strain). The bacterial communities in the sediments of Formosa and Penghu submarine canyons and Kaoping slope mainly dominated by Bacillus (50.0 %) in the phylum Fimicute and followed by Pseudoalteromonas (22.2 %) of the class Gammaproteobacteria in the phylum Proteaobacteria. Moreover, the bacterial composition of three samples in Formosa submarine canyon, Pehghu submarine canyon and Kaoping slope were similar. Pseudoalteromonas, Halomonas, Bacillus and Fictibacillus were found in these three samples. The strains of Marinobacter were only found in the Kaoping slope sample, and Halobacillus was only found in the Penghu submarine canyon sample.
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