Location: Food and Feed Safety ResearchTitle: Evaluation of antimicrobial action of chitosan and acetic acid on broiler cecal bacterial profiles in anaerobic cultures inoculated with Salmonella Typhimurium
|SOHAIL, MUHAMMAD - Qatar University
Submitted to: Journal of Applied Poultry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2018
Publication Date: 3/1/2019
Publication URL: https://handle.nal.usda.gov/10113/6471161
Citation: Sohail, M.U., Hume, M.E. 2019. Evaluation of antimicrobial action of chitosan and acetic acid on broiler cecal bacterial profiles in anaerobic cultures inoculated with Salmonella Typhimurium. Journal of Applied Poultry Research. 28(1):176-183. https://doi.org/10.3382/japr/pfy061.
Interpretive Summary: The chitin derivative chitosan is known to have antimicrobial properties against a range of microorganisms. The effects of chitosan preparations on bacterial populations were examined in broiler chicken intestinal bacteria cultures inoculated with Salmonella. Three different size chitosan preparations were used: low (L), medium (M), and coarse (C), using acetic acid (AA) to dissolve the chitosan. Intestine bacteria inoculated with Salmonella were cultured in five different treatment groups: 1) Salmonella and bacteria control; 2) AA plus Salmonella and intestine bacteria (AA); 3) L-treated S. Typhimurium and intestine bacteria; 4) M-treated Salmonella and intestine bacteria; and 5) C-treated Salmonella and intestine bacteria. Changes in intestine bacteria populations and Salmonella were assessed by automated DNA sequencing. Sequencing revealed zero Salmonella in the AA and the C groups. The AA and C groups also had lower numbers of bacteria and lower numbers of different kinds of bacteria. However, there were no differences in numbers of bacteria and the numbers of different kinds of bacteria among the groups given L, M, or C chitosan. In conclusion, culturing the broiler chicken intestinal bacteria in the presence of AA and C treatments suppressed bacterial growth as well as the numbers of different kinds of bacteria following anaerobic growth. Both L and M chitosan had no effect on Salmonella or bacterial growth, or on kinds of bacteria present. This information is of interest to poultry producers and food safety researchers seeking alternatives to antimicrobials against food-borne pathogens.
Technical Abstract: The chitin derivative chitosan is known to have antimicrobial properties against a range of microbes. Population effects of chitosan preparations were examined in broiler cecal bacterial anaerobic cultures inoculated with Salmonella Typhimurium. Three different molecular weight (MW) chitosan preparations were used: low (LMW), medium (MMW), and coarse (CMW), using acetic acid (AA) as carrier. Broiler cecal contents were inoculated with 10**5 CFU of S. Typhimurium and cultured anaerobically at 40 degrees Celsius for 24h in five treatment groups: S. Typhimurium inoculated cecal contents as control (CON), AA-treated S. Typhimurium inoculated cecal contents (AA), LMW-treated S. Typhimurium inoculated cecal contents, MMW-treated S. Typhimurium inoculated cecal contents, and CMW-treated S. Typhimurium inoculated cecal contents. The population effects of chitosan preparations on cecal bacteria were assessed by 16S rRNA Illumina-MiSeq high throughput sequencing. Sequencing revealed that the AA and CMW treatment groups also had lower bacterial diversity and species richness (alpha diversity index; chao1, Shannon, and observed species). Unweighted unifrac Beta diversity based PCoA plots revealed no significant differences in microbial diversity among the different treatment groups. Kruskal Wallis rank test analysis of treatment effects on taxonomic distribution of bacteria revealed no differences (P>0.05) in the percentages of identified bacteria among the different treatment groups. In conclusion, culturing the cecal contents in the presence of acetic acid and coarse chitosan treatments suppressed bacterial growth and diversity. Perhaps, both LMW and MMW chitosan preparations had no effect on either bacterial growth or diversity.