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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03629

    First report of a disease caused by Bacillus cereus in cultured loaches Paramisgurnus dabryanus

    Zhang Luo, Hanchang Sun, Shuang Hao, Youfu Ma, Zhenguo Zhang, ShouMing Feng, Xiaohui Bai*

    *Corresponding author:

    ABSTRACT: Bacillus cereus is commonly considered a bacteria pathogenic for mammals. However, several studies suggest it also induces diseases in fish. In 2017 and 2018, 2 strains, NQ-2017-7 and NQ-2018-8, were isolated from diseased large-scale loach Paramisgurnus dabryanus in Tianjin, China, and was considered to be the pathogen responsible for the disease. These stains were identified as B. cereus based on the results of 16S rDNA gene sequence analysis, Vitek biochemical tests, physiological and biochemical tests, and Bacillus cereus group species-specific PCR. Strains NQ-2017-7 and NQ-2018-8 were found to contain virulence genes (e.g. hblA, hblC, hblD, entFM, and bceT) causing pathological damage to the spleen, kidneys, liver, and gills of loaches. The median lethal dose (LD50) of NQ-2017-7 and NQ-2018-8 for loach were 1.0 ×106.64 CFU/mL and 1.0 ×106.49 CFU/mL, respectively. To our knowledge, this is the first report of loach disease caused by a member of the Bacillus genus.