养殖刺参附着期“化板症”病原菌的分离鉴定及来源分析

Etiology of off-plate syndrome in cultured larval Apostichopus japonicus at attachment stage and analysis of reservoir of pathogens

摘要:

摘要：【目的】查明养殖刺参附着期“化板症”的病原及其来源，并获得该病的治疗药物。【方法】分别对化板症状较为典型的3家育苗场的发病幼体进行病原学分析，对可疑病原进行人工回接感染并进行形态学、生理生化和16S rDNA序列分析鉴定，对各养殖场育苗系统，包括水源、养殖池水、池底污物、附着基板和饵料进行细菌学分析，对病原菌进行药敏测试。【结果】从所有病参中分离得到1种优势菌株，人工回接感染证明它对健康刺参有较强的致病性，且感染病参与自然发病刺参的症状相同。鉴定出“化板症”的病原为弧菌Vibrio sp.。养殖系统中除水源的细菌浓度没有超标污染 (<50 cfu/mL)外，其余均检出了大量细菌 (>1 × 105 cfu/mL)；病原来源较复杂：水源、养殖池水、池底污物、附着基板和饵料均发现了病原菌，但病原菌浓度以饵料中最多，附着基板次之，水源中最少。萘啶酸等12种常用抗生素可有效抑制该病原菌的生长。【结论】“化板症”的病原为弧菌Vibrio sp.；饵料可能为“化板症”病原的主要来源；萘啶酸等12种常用抗生素可用于该病的防治。

Abstract:

Abstract:【Objective】To clarify pathogens and sources of the off-plate syndrome at the attachment stage in the larval culture of Apostichopus japonicus, and further to find out effective medicines for this disease.【Methods】 Etiological analysis was performed on larvae with typical off-plate syndrome from three larvae culture factories. Suspicious pathogens were used for artificial infection test, and were identified through morphological, physiological and biochemical tests, and 16S rDNA sequence analysis. Quantitative bacterial analysis was done on the culture systems of the three factories, including water sources, rearing water, ordure (in the pond floor), attachments and feeds. Finally, drug-sensitive tests were done against the pathogens.【Results】A common dominant bacterium strain was isolated from all ill larvae included in the study. Artificial infection test showed it was the causative pathogen associated with the disease, and the artificially infected sea cucumbers had same syndromes to the naturally ill ones. The bacterium was identified as Vibrio sp. Bacterial quantity of water sources was in the qualified range (<50 cfu/mL), while out of the standard range in others (>1 × 105 cfu/mL). The sources of the pathogen were complicated, since pathogens were discovered in the water sources, rearing water, ordure, attachments and feeds. However, the density of causative bacteria was the highest in the feeds, middle in the attachments, and lowest in the water sources. Twelve antibiotics could inhibit growth of the pathogens.【Conclusion】The possible pathogen for off-plate syndrome was Vibrio sp. Feeds may be the main source of the pathogen. Twelve antibiotics besides nalidixic acid could be applied for disease prevention and treatment of Apostichopus japonicus.