Submitted to: Veterinary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2012
Publication Date: 9/14/2012
Citation: Levine, U.Y., Bearson, S.M., Stanton, T.B. 2012. Mitsuokella jalaludinii inhibits growth of Salmonella enterica serovar Typhimurium. Veterinary Microbiology. 159(1-2):115-122.
Interpretive Summary: Salmonella continues to be a significant human health threat which causes an estimated 1 million cases of illness due to food consumption each year. Of the microorganisms that cause sicknesses after food consumption, Salmonella is estimated to cause the most hospitalizations and deaths. An estimated 100,000 of those cases originate from pork products. The research reported here found 16 bacteria from the pig digestive system that, under laboratory conditions, are capable of preventing the growth of Salmonella enterica serovar Typhimurium. Four of these 16 bacteria were the baterium Mitsuokella jalaludinii. Products produced by M. jalaludinii during its growth were found to prevent S. Typhimurium growth, and S. Typhimurium invasion of cells. M. jalaludinii may prevent Salmonella growth and invasion in the digestive system of pigs, and therefore might be a bacterium that could be given to, or increased in pigs in order to reduce Salmonella in pork products. This research may lead to reductions of Salmonella in pork products, benefiting both the consumer and the farmer through increased food safety.
Technical Abstract: Salmonella continues to be a significant human health threat, and the objective of this study was to identify microorganisms with the potential to improve porcine food-safety through their antagonism of Salmonella. Anaerobic culture supernates of 973 bacterial isolates from the gastrointestinal tract and feces of swine were screened for their capacity to inhibit the growth of Salmonella enterica serovar Typhimurium. Growth inhibition of 1000-fold or greater was observed from 16 isolates, and 16S rRNA sequencing identified the isolates as members of the genera Mitsuokella, Escherichia/Shigella, Anaerovibrio, Selenomonas, and Streptococcus. Four isolates were identified as Mitsuokella jalaludinii, and the mechanism of S. Typhimurium growth inhibition by M. jalaludinii was further investigated. M. jalaludinii stationary phase culture supernates were observed to significantly inhibit growth, and featured the greatest production of lactic, succinic, and acetic acids. Aerobic and anaerobic S. Typhimurium growth was restored when the pH of the culture supernates (pH 4.6) was changed to pH 6.8. However, S. Typhimurium growth in fermentation acid-free media was the same at pH 4.6 and pH 6.8 – indicating a synergistic effect between fermentation acid production and low pH as the cause of S. Typhimurium growth inhibition. Furthermore, exposure of S. Typhimurium to M. jalaludinii culture supernates inhibited Salmonella invasion of HEp-2 cells by 10-fold. The results identify M. jalaludinii as a possible probiotic in swine with the potential to improve food safety through the inhibition of Salmonella growth and invasion.