College of Fisheries, Tianjin Agricultural University, Tianjin 300384, PR China.
Dis Aquat Organ. 2022 Jul 7;150:53-60. doi: 10.3354/dao03674.
A disease outbreak occurred in Murray cod Maccullochella peelii peelii in a recirculating aquaculture farm in Tianjin city, China, in 2019. Strain MRX-2019 was isolated and considered to be the etiological pathogen; it was identified as Flavobacterium columnare based on a 16S rDNA gene sequence analysis and physiological and biochemical tests. The effect of salinity on the growth of MRX-2019 was investigated in vitro. Salinity >4‰ (i.e. 6‰) inhibited MRX-2019 growth, whereas 8 and 10‰ salinity killed it. The effect of 4‰ salinity on F. columnare was not significant (p > 0.05). When MRX-2019-infected Murray cod were treated with 4, 6, or 8‰ salinity, the mortality rate was reduced by 8.9, 67.76, or 75.56%, respectively, compared with that of the control. However, the mortality rate increased by 7.77% at 10‰ salinity. In this study, we found that maintaining the fish in freshwater with 6-8‰ salinity effectively reduced the mortality of these fish when infected with F. columnare. The findings provide an environmentally friendly control strategy for columnaris disease in Murray cod.
2019 年，中国天津市的一家循环水产养殖场发生了麦瑞加拉鲮（Maccullochella peelii peelii）疾病爆发。分离出的菌株 MRX-2019 被认为是病因病原体；通过 16S rDNA 基因序列分析和生理生化试验，将其鉴定为柱状屈挠杆菌（Flavobacterium columnare）。在体外研究了盐度对 MRX-2019 生长的影响。盐度>4‰（即 6‰）抑制 MRX-2019 的生长，而 8‰和 10‰的盐度则将其杀死。4‰盐度对柱状屈挠杆菌的影响不显著（p>0.05）。当用 4‰、6‰或 8‰盐度处理感染了 MRX-2019 的麦瑞加拉鲮时，与对照组相比，死亡率分别降低了 8.9%、67.76%和 75.56%。然而，在 10‰盐度下，死亡率增加了 7.77%。在这项研究中，我们发现将鱼饲养在盐度为 6-8‰的淡水中，可有效降低这些鱼在感染柱状屈挠杆菌后的死亡率。这些发现为麦瑞加拉鲮的柱状屈挠杆菌病提供了一种环保的控制策略。
