ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Microbial Symbioses
Volume 16 - 2025 | doi: 10.3389/fmicb.2025.1623741
This article is part of the Research TopicInnovative Approaches to Modulate Fish Gut Microbiota for Disease Management in AquacultureView all 5 articles
Pathogenicity and Whole-Genome Analysis of a Siniperca chuatsi-Derived Nocardia seriolae Strain
Provisionally accepted
Liting Chen
Xin YanYongju LuoZhuanling LuXinxian WeiZhanyang Tang
Liqun XiaFuyan ChenMing LiZhongbao GuoZhichang He
Ting Huang*- Guangxi Academy of Fishery Sciences, Nanning, China
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A bacterial strain (No. 20230510) was isolated from the kidneys of diseased Siniperca chuatsi in Guangxi, China, since 2023. Artificial infection experiments demonstrated that this strain caused the observed disease in S. chuatsi. The isolate underwent morphological, pathological, genomic (whole-genome sequencing, WGS), and antibiotic susceptibility analyses. Infection trials revealed 100% mortality in high-concentration groups, with an LD50 of 3.89×10⁴ CFU/ml, indicating high virulence. WGS results showed a circular chromosome of 8,123,106 bp (GC content: 68.14%), containing 7,638 CDSs, 72 tRNAs, and 12 rRNAs. Phylogenomic analysis revealed that strain 20230510 (CP130742) clusters with three N. seriolae strains with 98% bootstrap supporting, confirming its identification as N. seriolae. Further analysis identified 403 potential virulence genes linked to nutrient metabolism, regulatory factors, immune modulation, effector delivery systems, and exotoxins. Chromosomal comparisons also detected multiple antibiotic resistance genes. Susceptibility testing confirmed sensitivity to nine antibiotics, including enrofloxacin, doxycycline, florfenicol, and sulfamethoxazole. Histopathology revealed chronic granulomatous lesions, most severe in the kidneys, with similar but milder damage in the liver, spleen, gills, and intestines. These results confirm N. seriolae strain 20230510 as the pathogenic agent behind S. chuatsi mortality, offering key insights for developing control strategies.
Keywords: Siniperca chuatsi, Nocardia seriolae, pathogenicity, Whole-genome analysis, antibiotic susceptibility testing
Received: 07 May 2025; Accepted: 23 Jul 2025.
Copyright: © 2025 Chen, Yan, Luo, Lu, Wei, Tang, Xia, Chen, Li, Guo, He and Huang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Ting Huang, Guangxi Academy of Fishery Sciences, Nanning, China
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