{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,12]],"date-time":"2026-08-12T15:47:10Z","timestamp":1786549630353,"version":"build-2736575974"},"reference-count":32,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2026,8,12]],"date-time":"2026-08-12T00:00:00Z","timestamp":1786492800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Science and Technology Project of Fujian Province","award":["2023J01763"],"award-info":[{"award-number":["2023J01763"]}]},{"name":"Science and Technology Project of Fujian Province","award":["2026J001772"],"award-info":[{"award-number":["2026J001772"]}]},{"name":"Xiamen Science and Technology Subsidy Project","award":["No. 2024CXY0307"],"award-info":[{"award-number":["No. 2024CXY0307"]}]},{"name":"Educational Office of Fujian Province","award":["[2023]20, FBJY20230312"],"award-info":[{"award-number":["[2023]20, FBJY20230312"]}]},{"name":"Open Research Fund Program of Fujian Provincial Key Laboratory of Marine Fishery Resources and Eco-environment","award":["JD202402"],"award-info":[{"award-number":["JD202402"]}]},{"name":"Open ResFujian Provincial Department of Science and Technology","award":["[2023]15, 2023S2030"],"award-info":[{"award-number":["[2023]15, 2023S2030"]}]},{"award":["[2023]15, 2023S2030"],"award-info":[{"award-number":["[2023]15, 2023S2030"]}],"id":[{"id":"https:\/\/ror.org\/00rgzpv08","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>The aquatic pathogen Aeromonas salmonicida SRW-OG1 is responsible for substantial mortality in Epinephelus coioides and many other cultured fish species. This study investigates the contribution of trpE to the pathogenicity of A. salmonicida SRW-OG1 in E. coioides. Specifically, trpE encodes a key enzyme in tryptophan biosynthesis; however, its function in regulating virulence in A. salmonicida remains uncertain. Phenotypic assays indicate that deletion of trpE markedly impaired bacterial growth and significantly reduced multiple virulence-associated traits, including swimming motility, biofilm formation, chemotaxis, hemolytic activity, and extracellular enzyme activity. Transmission electron microscopy revealed that the \u0394trpE mutant lacked flagella, indicating that trpE is involved in flagellar formation or maintenance. In an E. coioides infection model, fish infected with \u0394trpE showed a cumulative survival rate of 48.3%, whereas those infected with the wild-type SRW-OG1 suffered 100% mortality. The \u0394trpE mutant also exhibited reduced bacterial loads in target organs (liver, head kidney, and spleen), while pretreatment with \u0394trpE provided 53.3% protection against a subsequent wild-type challenge. Transcriptomic analysis identified 616 differentially expressed genes, mainly enriched in pathways including flagellar assembly, bacterial chemotaxis, two-component systems, quorum sensing, and biofilm formation. Metabolomic analysis further showed a significant decrease in N-butyryl-L-homoserine lactone, an acyl-homoserine lactone quorum-sensing signal in the \u0394trpE mutant. These findings suggest that trpE contributes to mesophilic A. salmonicida SRW-OG1\u2019s virulence by partially affecting quorum-sensing signal production and motility-related pathways. The attenuated phenotype and protective effect of \u0394trpE indicate its potential as a live attenuated vaccine candidate for controlling A. salmonicida infection in aquaculture.<\/jats:p>","DOI":"10.3390\/ani16162521","type":"journal-article","created":{"date-parts":[[2026,8,12]],"date-time":"2026-08-12T14:45:06Z","timestamp":1786545906000},"page":"2521","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["The Tryptophan Biosynthesis Gene trpE Contributes to Virulence in Mesophilic Aeromonas salmonicida SRW-OG1"],"prefix":"10.3390","volume":"16","author":[{"given":"Zhixing","family":"Zhang","sequence":"first","affiliation":[{"name":"Fisheries College, Jimei University, Xiamen 361021, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qiang","family":"Chen","sequence":"additional","affiliation":[{"name":"Fisheries College, Jimei University, Xiamen 361021, China"},{"name":"State Key Laboratory of Mariculture Breeding, Fujian Provincial Key Laboratory of Marine Fishery Resources and Eco-Environment, Fisheries College, Jimei University, Xiamen 361021, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4704-4153","authenticated-orcid":false,"given":"Xiaojin","family":"Xu","sequence":"additional","affiliation":[{"name":"Fisheries College, Jimei University, Xiamen 361021, China"},{"name":"State Key Laboratory of Mariculture Breeding, Fujian Provincial Key Laboratory of Marine Fishery Resources and Eco-Environment, Fisheries College, Jimei University, Xiamen 361021, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xufei","family":"Liu","sequence":"additional","affiliation":[{"name":"Fisheries College, Jimei University, Xiamen 361021, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yujin","family":"Xiao","sequence":"additional","affiliation":[{"name":"Fisheries College, Jimei University, Xiamen 361021, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chengcheng","family":"Li","sequence":"additional","affiliation":[{"name":"Fisheries College, Jimei University, Xiamen 361021, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuxuan","family":"Sha","sequence":"additional","affiliation":[{"name":"Fisheries College, Jimei University, Xiamen 361021, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lunrui","family":"Zhang","sequence":"additional","affiliation":[{"name":"Fisheries College, Jimei University, Xiamen 361021, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Genhuang","family":"Xu","sequence":"additional","affiliation":[{"name":"Fisheries College, Jimei University, Xiamen 361021, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Guiling","family":"Zhang","sequence":"additional","affiliation":[{"name":"Fisheries College, Jimei University, Xiamen 361021, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pocheng","family":"Chen","sequence":"additional","affiliation":[{"name":"Fisheries College, Jimei University, Xiamen 361021, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"127995","DOI":"10.1016\/j.micres.2024.127995","article-title":"Decoding bacterial communication: Intracellular signal transduction, quorum sensing, and cross-kingdom interactions","volume":"292","author":"Liu","year":"2025","journal-title":"Microbiol. 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