COMPARISON OF SALMONELLA-TYPHIMURIUM AND SELECTED FACULTATIVE CHICKENCECAL BACTERIA SURVIVABILITY AFTER SPECIFIC AMINO ACID-LIMITED BATCH GROWTH

The objective of this in vitro experimentation was to compare the surv ivability of Salmonella typhimurium strains and selected facultative c hicken cecal bacteria after specific amino acid-limited growth on eith er serine, threonine, arginine, or aspartate. Survivability of Salmone lla typhimurium and chicken cecal bacteria was estimated by measuring the rate of decrease of viable cell numbers and calculating the averag e time for 50% of the cells to become nonviable (50% survival time, ST 50). Two S. typhimurium strains, LT2 and a primary poultry isolate (NO /NA), and three selected facultative chicken cecal bacteria, Citrobact er freundii, Escherichia coli and Escherichia fergusonii, were grown a erobically at 37 degrees C to stationary phase on carbon-limited or ni trogen-limited minimal media. All organisms remained viable longer (P < 0.05) on serine media than on any of the other media tested. When se rine was used as a nitrogen source in minimal media the ST50 of C. fre undii and E. fergusonii were significantly longer than those of the tw o S. typhimurium strains. It appears that when media are limited in th e same nutrient, the ability to sustain viability varies among faculta tive bacteria derived from the chicken cecum.