Pullorum disease, caused by Salmonella enterica serovar Pullorum (S. Pullorum), is one of the most important bacterial infections in the poultry industry in developing countries, including China. To examine the prevalence and characteristics of S. Pullorum, the Multilocus Sequence Typing (MLST) genotypes, fluoroquinolones resistance, and biofilm-forming abilities of S. Pullorum isolates were investigated, collected from 2011 to 2016 in China. Thirty S. Pullorum isolates collected from 2011 to 2016 were analyzed. Quinolones susceptibility testing showed that 90% of the isolates were resistant to the first generation of quinolines nalidixic acid, but the resistance rates to different fluoroquinolones agents were lower than 13.3%; for some there was even no resistance. Multilocus sequence typing (MLST) showed that ST-92 was the dominating genotype, accounting for 90.0% of all S. pullorum strains. The remaining three isolates were of the new reported sequence type ST-2151. Interestingly, the Asp87Gly substitution in quinolone resistance-determining regions (QRDR) of GyrA was only observed in the three strains of ST-2151, suggesting a potential correlation between Asp87Gly substitution and sequence type (p < 0.05). However, Asp87Gly substitution could not confer the resistant to ofloxacin and ciprofloxacin of these isolates. The plasmid-mediated quinolone resistance (PMQR) gene was not found in any of the tested isolates. Furthermore, an assay measuring biofilm-forming abilities showed that 46.7% of the isolates were non-biofilm producers, while 53.3% could form very weak biofilms, which might explain the relatively lower resistance to fluoroquinolones. We reported a high resistance rate to the first generation of quinolines nalidixic acid and relatively low resistance rates to fluoroquinolones in S. Pullorum isolates. In addition, weak biofilm-forming abilities were found, which might be an important reason of the low fluoroquinolones resistance rates of S. Pullorum isolates. ST-92 was the dominating genotype demonstrated by MLST, and the new sequence type ST-2151 showed a potential correlation with Asp87Gly substitution in QRDR of GyrA. We believe the characterization of these S. Pullorum isolates will be helpful to develop prevention and control strategies.

Pullorum disease, caused by Salmonella Pullorum (S. Pullorum), is one of the most serious infectious diseases in the poultry industry. Flos populi is traditionally used in Eastern Asian countries to treat various intestinal diseases. However, the anti-infection mechanism of Flos populi is not very clear. In this study, we evaluated the anti-infective effects on S. Pullorum of Flos populi aqueous extract (FPAE) in chickens. FPAE significantly reduced S. Pullorum growth in vitro. At the cellular level, FPAE reduced S. Pullorum adhesion and invasion on DF-1 cells but did not affect its intracellular survival or replication in macrophages. Further investigation revealed that FPAE inhibited the transcription of T3SS-1 genes, which is the main virulence factor that mediates S. Pullorum adhesion and invasion in host cells. The results suggest that the anti-infective effect of FPAE likely occurs through the inhibition of S. Pullorum T3SS-1, thereby impairing its ability to adhere to and invade cells. Further, we evaluated its therapeutic effect on animal models (Jianghan domestic chickens) and found that FPAE reduced the bacterial loads in organs and decreased the mortality and weight loss of infected chickens. Our findings provide novel insights into the potential development of FPAE against S. Pullorum as an effective anti-virulence therapeutic substitute for antibiotics.

Marine bacteria represent a vast and largely untapped resource for biotechnological innovation, offering solutions to global challenges in health, sustainability, and environmental conservation. The ocean’s unique conditions have driven marine bacteria to evolve diverse metabolic capabilities, resulting in the production of bioactive compounds, enzymes, and other metabolites with wide-ranging applications. Recent advances in high-throughput sequencing, metagenomics, and analytical chemistry have unlocked new opportunities for leveraging these microorganisms in fields as varied as medicine, agriculture, and bioremediation. This review highlights the role of marine bacteria in the One Health framework, showcasing their contributions to antimicrobial discovery, nutraceutical development, pathogen biocontrol, and environmental cleanup, including microplastic degradation. This review also examines emerging methodologies such as microbiome mining and advanced culturing techniques, which hold the key to realizing the full potential of marine bacteria in a sustainable bioeconomy. By bridging fundamental research with applied sciences, marine biotechnology promises to deliver transformative impacts on human, animal, and environmental health.

The increasing detection of Riemerella anatipestifer in chickens poses severe challenges to the poultry industry. However, the genomic differences among R. anatipestifer isolates from different poultry hosts remain poorly understood. Here, we investigated host-associated genomic differences among 158 R. anatipestifer strains isolated from different hosts in China, using pan-genome, phylogenetic, virulence factor, and antimicrobial resistance analyses. The core-genome phylogeny showed no apparent separation according to host, sampling period, or geographic origin. Conserved genes including groEL, tufA, and katB were detected in all strains, whereas tviB and ureG displayed host-associated distribution patterns. More than 40 putative antimicrobial resistance (AMR) genes were detected across 158 R. anatipestifer strains, indicating the presence of multiple putative AMR determinants. Among these, bla_RAD-1, bla_RASA-1, and dfrA36 exhibited host-associated distribution patterns. Pan-genome analysis further identified host-associated genomic differences in R. anatipestifer. These included genes contributing to cell-surface modification pathways mediated by pglH, and genes involved in toxin–antitoxin system-dependent stress regulation via parD1/parE1 and yefM-yoeB. Overall, our comparative genomic characterization of R. anatipestifer characterizes host-associated genomic differences and provides a basis for further investigation of their biological significance.