Evaluation of Antimicrobial Action of Chitosan and Acetic Acid on Broiler Cecal Bacterial Profiles in Anaerobic Cultures InoculatedWith Salmonella Typhimurium

Abstract

Chitosan is known to have antimicrobial properties against a range of microbes. In this study, three different molecular weight (MW) chitosan preparations were used: low (LMW), medium (MMW), and coarse (CMW), in acetic acid (AA) as carrier to elucidate antimicrobial effects. Broiler cecal contents were inoculated with 105 CFU of S. Typhimurium and cultured anaerobically at 40◦C with AA, LMW, MMW, or CMW. The population effects of chitosan preparations on cecal bacteria and S. Typhimurium were assessed by 16S rRNA sequencing. Sequencing revealed zero prevalence of Salmonella spp. in the AA and the CMW groups. The AA and CMW groups had also lower bacterial diversity and species richness. However, PCoA plots revealed no significant differences in microbial diversity among the different treatment groups. Kruskal-Wallis test analysis of treatment effects on taxonomic distribution of bacteria revealed no differences (P > 0.05) in the percentages of bacteria among the different groups. In conclusion, culturing the cecal contents in the presence of AA and CMW treatments suppressed bacterial growth and within sample bacterial diversity. Both LMW and MMW chitosan preparations had no effect on either S. Typhimurium or bacterial growth and diversity.