|Ha, S - TEXAS A&M UNIVERSITY|
|Ricke, Steven - TEXAS A&M UNIVERSITY|
Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 26, 1996
Publication Date: N/A
Interpretive Summary: Some bacteria live longer under stressful conditions, e.g.,nutrient deprivation. One of the reasons for certain bacterial species to survive longer is due to the presence of certain growth limiting nutrients prior to nutrient deprivation. Some amino acids, serine, threonine, arginine and aspartic acid, have been identified as important nutrients to Salmonella typhimurium for proper growth. This study was to compare the survivability of Salmonella to three different chicken bacteria after different growth limiting conditions. All of the organisms remained viable longer after being grown previously in a medium containing serine. Some native chicken bacteria, e.g., Citrobacter freundii and Esherichia fergusonii, lived longer than Salmonella. This research demonstrates that some native chicken bacteria can outlive Salmonella under certain starvation conditions. This information will be beneficial to researchers trying to understand complex interactions in mixed microbial systems such as the gastrointestinal tract of poultry.
Technical Abstract: The objective of this in vitro experimentation was to compare the survivability of Salmonella typhimurium strains and selected facultative chicken cecal bacteria after specific amino acid-limited growth on either serine, threonine, arginine, or aspartate. Survivability of Salmonella typhimurium and chicken cecal bacteria was estimated by measuring the rate of decrease of viable cell numbers and calculating the average time for 50% of the cells to become nonviable (50% survival time, ST50). Two S. typhimurium strains, LT2 and a primary poultry isolate (NO/NA), and three selected facultative chicken cecal bacteria, Citrobacter freundii, Escherichia coli and E. fergusonii, were grown aerobically at 37C to stationary phase on carbon-limited or nitrogen-limited minimal media. All organisms remained viable longer (P<0.05) on serine media than on any of the other media tested. When serine was used as a nitrogen source in minimal media, the ST50 of C. freundii and E. fergusonii were significantl longer than those of the two S. typhimurium strains. It appears that when media are limited in the same nutrient, the ability to sustain viability varies among facultative bacteria derived from the chicken cecum.