AUTHOR=Yan Pupu , Liu Jiali , Huang Yongxi , Yi Tilin , Zhang Heng , Dai Gang , Wang Xiong , Gao Zhenzhen , He Bin , Guo Weili , Su Yingbing , Guo Liwei 

TITLE=Baicalin enhances antioxidant, inflammatory defense, and microbial diversity of yellow catfish (Pelteobagrus fulvidraco) infected with Aeromonas hydrophila

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1465346

DOI=10.3389/fmicb.2024.1465346

ISSN=1664-302X

ABSTRACT=<sec><title>Introduction</title><p>The aim of this research was to clarify the mechanism through which baicalin exerts its inhibitory effects on <italic>Aeromonas hydrophila</italic> infection.</p></sec><sec><title>Methods</title><p>The antibacterial efficacy of baicalin was assessed by determining its minimum inhibitory concentration (MIC) against <italic>A. hydrophila</italic>. Various parameters, including the growth curve, cell wall integrity, biofilm formation, AKP content, and morphological alterations of <italic>A. hydrophila</italic>, were analyzed. In vivo experiments involved the administration of <italic>A. hydrophila</italic> 4 h postintraperitoneal injection of varying doses of baicalin to induce infection, with subsequent monitoring of mortality rates. After a 3 d period, liver, spleen, and intestinal tissues were harvested to evaluate organ indices, antioxidant and immune parameters, as well as intestinal microbial composition.</p></sec><sec><title>Results</title><p>The findings indicated that baicalin treatment resulted in the disruption of the cell wall of <italic>A. hydrophila</italic>, leading to the loss of its normal structural integrity. Furthermore, baicalin significantly inhibited biofilm formation and facilitated the release of intracellular proteins (<italic>P</italic> &lt; 0.05). In vivo, baicalin enhanced the survival rates of yellow catfish infected with <italic>A. hydrophila</italic>. Compared to the control group, the liver index of yellow catfish was elevated, while the spleen and intestinal indices were reduced in the baicalin-treated group (<italic>P</italic> &lt; 0.05). Additionally, baicalin at an appropriate dosage was found to increase levels of SOD, GSH, CAT, ACP, and AKP in yellow catfish (<italic>P</italic> &lt; 0.05), while simultaneously decreasing MDA accumulation and the mRNA expression of inflammatory markers such as Keap1, IL1, IFN-γ, and TNF-α, (<italic>P</italic> &lt; 0.05). Moreover, baicalin significantly enhanced the operational taxonomic unit (OTU) count in <italic>A. hydrophila</italic>-infected yellow catfish (<italic>P</italic> &lt; 0.05), restoring the abundance of Barnesiellaceae, Enterobacteriaceae, Plesiomonas, and <italic>UBA1819</italic> (<italic>P</italic> &lt; 0.05).</p></sec><sec><title>Discussion</title><p>In summary, baicalin demonstrates the potential to improve the survival rate of yellow catfish subjected to <italic>A. hydrophila</italic> infection, augment antioxidant and immune responses, mitigate inflammation, and enhance intestinal microbial diversity.</p></sec>