First Report and Integrated Characterization of Aeromonas veronii Associated with the Protected Fish Diptychus maculatus in Xinjiang, China

Abstract

Simple Summary Diptychus maculatus is a second-class protected cold-water fish inhabiting ecologically sensitive high-altitude aquatic ecosystems. Yet, there is limited information on the bacteria associated with this species. In this study, bacteria were recovered from multiple tissues of D. maculatus and characterized based on phenotypic, biochemical, and molecular analyses. The recovered isolates were identified as Aeromonas veronii based on phenotypic characterization and 16S rRNA gene sequencing, with additional gyrB confirmation performed for a representative isolate. As A. veronii is an important opportunistic aquatic pathogen, its antimicrobial susceptibility profile and biofilm-forming ability were evaluated. The isolates exhibited similar responses to the tested antimicrobial agents and demonstrated weak-to-moderate biofilm formation under laboratory conditions. These findings offer baseline data on the occurrence and phenotypic traits of A. veronii in a protected fish species and contribute to conservation-oriented wildlife microbial surveillance in high-altitude aquatic ecosystems. The study highlights the need for future investigations into host-associated microbial diversity, microbial ecology, genomics and conservation-oriented monitoring of protected fish populations to gain a better understanding of their ecological and health-related implications.