Ribosomal protein L32 contributes to the growth, antibiotic resistance and virulence of Glaesserella parasuis

<i>Glaesserella parasuis</i> is the pathogen that causes Glässer's disease in pigs, which is characterized by fibrinous polyserositis, arthritis and meningitis. Research on ribosomal protein L32 in microorganisms has mainly focused on regulating gene transcription and translation, but its effect on bacterial virulence is unclear. The role of <i>L32</i> gene in <i>G. parasuis</i> is not clear, and in order to study the function of <i>L32</i> gene, a suicide plasmid-mediated natural transformation method was used to construct a <i>L32</i> gene deletion mutant. We found that although <i>L32</i> was shown to be non-essential for cell proliferation, the growth curve of Δ<i>L32</i> is clearly different compared with that of ZJ1208. Δ<i>L32</i> produced more outer membrane vesicles (OMVs) with a variety of irregular shapes, but produced similar biofilm to the parental strain. Δ<i>L32</i> is more sensitive to osmotic pressure, oxidation pressure and heat shock stress. Meanwhile, Δ<i>L32</i> is significantly more susceptible to antimicrobials such as spectinomycin, apramycin, sulfafurazole, but not to other antibiotics used in this study. In the mouse challenge experiment, the mortality of mice infected with the mutant strain decreased by 40% compared to those infected with the wild-type strain, indicating that <i>L32</i> is a virulence-associated factor which contributes to bacterial fitness in host environments. The above results show that <i>L32</i> is important for the growth, stress resistance and virulence of <i>G. parasuis</i>, and this study also confirms for the first time that <i>L32</i> plays an important role in antibiotic resistance against aminoglycosides and sulfonamides.