军曹鱼肠道及水体异养菌和弧菌的周年变化

Annual changes of heterotrophic bacteria and vibrios in intenstine and rearing water of maricultured cobia,Rachycentron cannadum Linnaeus

采用总活异养菌2216E平板计数法和弧菌TCBS平板计数法对广东深圳大鹏养殖军曹鱼(Rachycentron canadum Linnaeus)养殖水体及鱼肠道细菌进行了周年监测。结果显示,育苗初期养殖水体异养菌和弧菌密度分别为0.63×104～6.2×104CFU/mL和0.30×102～1.03×104CFU/mL,鱼肠道异养菌和弧菌密度分别为0.80×106～7.5×107CFU/g和0～1.30×107CFU/g;网箱养殖监测期间,养殖水体异养菌和弧菌密度分别为4.20×103～5.40×105CFU/mL和0.70×102～1.14×105CFU/mL,鱼肠道异养菌和弧菌密度分别为1.50×107～8.78×108CFU/g和1.00×107～3.50×108CFU/g。周年监测结果显示,水体异养菌、弧菌的数量高峰均出现于8-9月份;肠道异养菌及弧菌的数量高峰均出现于6-7月份,分别又在12月份和2月份出现次高峰,弧菌变化趋势始终与异养菌一致。对分离得到的407株菌鉴定到属并进行多样性分析。结果显示,育苗期水体以假单胞菌(Pseudomonas)、黄单胞菌(Xanthomonas)和芽孢杆菌(Bacillus)为优势菌,三者约占水体异养菌总数的70%;养殖后期,弧菌(Vibrio)和发光杆菌(Photobacterium)的数量逐渐上升并占据一定优势,其中假单胞菌、黄单胞菌、弧菌和芽孢杆菌常年出现。鱼肠道异养菌以假单胞菌和芽孢杆菌为优势菌,其次是肠杆菌科(Enterbacteriaceae)细菌,也多次检测到弧菌、发光杆菌、气单胞菌(Aeromonas)和小球菌(Microccus)等。总之,养殖微生态系统的可持续稳定平衡与系统的种群多样性、群落组成及水质因子等因素相关,而整个环境生态系统的平衡直接影响到鱼类肠道的细菌生态系统。

Heterophic bacteria and vibrios in intenstine and Shenzhen, Guangdong provence, were analyzed annually rearing water of cobia fanned in dapeng county, by 2216E plate smearing and TCBS smearing, respectively, quantities of heterotrophic bacteria and vibrios during early days of breeding ranged from 0.63 × 10^4-6.2 × 10^4 CFU/mL and 0.30 × 10^2-1.03 × 10^4 CFU/mL in the rearing water, and 0.80 × 10^6-0.75 × 10^7 CFU/ g and 0-1.30 × 10^7CFU/g in intestine of the cobia, respectively, in early stage of development. Quantities of heterotrophic bacteria and vibrios were very low at very beginning. When juvenile cobia cultured in the cage, quantities of heterotrophic bacteria and vibrios ranged from 4.20 × 10^3-5.40 × 10^6 CFU/mL and 0.70 × 10^2-0.14 × 10^5 CFU/mL in the seawater, andl.50 × 10^7-8.78 × 10^8 CFU/g and 1.00 × 10^7-3.50 × 10^8 CFU/g in intestine of the cobia, respectively. Quantitaties of heterotrophic bacteria and vibrios in cage-cultured water and intestine of cobia increased rapidly and soon reached their peak numbers. Highest value appeared in September for heterotrophic bacteria and vibrios in the water and July in intestine of cobia. 407 bacterial strains were isolated and identified. Pseudomonas, Xanthornonas and Bacillus were the most dominant species at early stage in the seawater （prevalence of the three genera 70%）, and followed by the Vibrio and Photobacterium, Pseudomonas, Xanthomonas, and Bacillus presenting in the water throughout the whole year. Heterotrophic bacteria in intestine of cobia showed well-distributed. Pseudomonas and Bacillus were the most dominant species, and followed by Enterbacteriaceae. Vibrio, Photobacterium, Aeromonas and Microccus were also detected from the intestine of cobia in annual monitor. [Journal of Fishery Sciences of China, 2008, 15 （6） ： 1 008-1 015]