广东省养殖罗非鱼、海鲈、尖吻鲈海豚链球菌感染调查

利用细菌分离培养方法结合特异PCR技术,对广东省珠三角地区养殖罗非鱼(Oreochromis spp.)、海鲈(Lateolabrax japonicus)及尖吻鲈(Lates calcarifer)的海豚链球菌(Streptococcus iniae)感染情况进行了周年调查。每月固定时间在特定养殖区域采集目标鱼的脑、肝、脾、肾和肌肉等组织,并对其进行海豚链球菌的细菌分离培养鉴定。仅从已经患病的尖吻鲈中分离到3株链球菌,经生理生化鉴定和16S rDNA测序确定为海豚链球菌。利用海豚链球菌特异PCR技术对上述养殖鱼类不同组织进行检测,发现罗非鱼、海鲈、尖吻鲈的海豚链球菌感染率分别为30.21%、23.53%、14.55%,其中罗非鱼脑和肌肉的感染率明显较其他组织高(P<0.05),分别为20.65%和23.75%;海鲈的脑部和肌肉感染率也较其他组织高(P<0.05),分别为12.1%和10%;而尖吻鲈各组织感染率没有较大差异(P>0.05)。另外,研究结果还表明采集样本的海豚链球菌感染率随着其体长的增加而呈现下降趋势。

Streptococcus iniae infection in cultured tilapia, sea bass, and barramundi in Guangdong

Streptococcus iniae infects a number of cultured fish species,causing heavy economic loss in Guang-dong province.We evaluated the prevalence of infection with S.iniae in tilapia(Oreochromis spp.),sea bass(Lateolabrax japonicus),and barramundi(Lates calcarifer) using a standard microbiological assay and specific PCR.Using PCR,we detected S.iniae in all three species(30.21%,23.53%,and 14.55% of individuals,respec-tively).However,S.iniae was only isolated from three barramundi using the traditional microbiological assay.S.iniae was detected in all tissues,including brain,liver,spleen,kidney,and muscle.The brain and muscle were more susceptible to S.iniae than the other tissues in tilapia(infection rate: 20.65% and 23.75%,respectively) and sea bass(infection rate: 12.1% and 10%,respectively).There was no difference in the susceptibility of the tissues in barramundi.Moreover,our results suggested that body length was inversely correlated with the infection rate by S.iniae.