Isolation and identification of pathogenic bacteria associated with “rot disease” of hybrid yellow catfish (Pelteobagrus fulvidraco,♀×P.vachell,♂)

doi:10.16535/j.cnki.dlhyxb.2023-279

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Journal of Dalian Fisheries University ›› 2024, Vol. 39 ›› Issue (6) : 1011-1020. DOI: 10.16535/j.cnki.dlhyxb.2023-279

Isolation and identification of pathogenic bacteria associated with “rot disease” of hybrid yellow catfish (Pelteobagrus fulvidraco,♀×P.vachell,♂)

DENG Changwen，LIAO Qingqing，REN Yingying，LIN Yazhou，ZHANG Bowen，MAN Tenglong，LI Yunkun，DU Xiaogang，YANG Shiyong，WU Jiayun*

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Abstract

In order to recognize the pathogenic bacterial characteristics of hybrid yellow catfish (Pelteobagrus fulvidraco,♀×P.vachell,♂) “Huangyou No.1” with “rot disease”, a dominant strain from the skin of diseased catfish was isolated and cultured, and the pathogenicity and the species pathogen were determined in healthy “Hwangyou No. 1” with body weight of 45.3-55.2 g and glossy yellow catfish (P.nitidus) with body weight of 31.9-41.7 g) by artificial infection test, and confirm by comprehensive morphological observation, physiological and biochemical identification, as well as16SrRNA gene sequence analysis. The virulence gene and drug sensitivity of the strain were detected by PCR method, and antibiotic drug sensitivity tests. The results showed that the strain was a Gram-negative bacterium, with 15 days LD50 of 2.11×108 CFU/mL for the hybrid yellow catfish and 4.27×108 CFU/mL for P. nitidus, by artificial regression infection. The physiological and biochemical identification, and the sequencing analysis confirmed that the strain was Pseudomonas fluorescens. Virulence gene testing showed that it carried virulence genes including fur, hly, hem0, fha, pspb and tfeR. The strain was a multi-drug resistant strain, highly sensitive to 4 antibiotics including doxycycline, gentamicin, benznidazole and tetracycline, and resistant to 14 antibiotics including penicillin in drug sensitivity tests. The P.fluorescens is first reported a potential pathogen causing “rotten disease” in hybrid yellow catfish, and that also cause similar disease in P.nitidus.The findings provide scientific basis for the prevention and treatment of rotten disease in yellow catfish.

Key words

Pelteobagrus fulvidraco / rotten disease / Pseudomonas fluorescens / pathogen identification / drug sensitivity test / virulence gene

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DENG Changwen, LIAO Qingqing, REN Yingying, LIN Yazhou, ZHANG Bowen, MAN Tenglong, LI Yunkun, DU Xiaogang, YANG Shiyong, WU Jiayun. Isolation and identification of pathogenic bacteria associated with “rot disease” of hybrid yellow catfish (Pelteobagrus fulvidraco,♀×P.vachell,♂)[J]. Journal of Dalian Fisheries University, 2024, 39(6): 1011-1020 https://doi.org/10.16535/j.cnki.dlhyxb.2023-279