The interactions of typical spoilage causing microorganisms (lactic acid bacteria, coliforms, Pseudomonads, Brochothrix thermosphacta, Salmonella, yeasts) growing on sliced pork shoulder were investigated. Microbial counts at 1, 3, 4, 7, 10, and 15 days at 5 degrees C were fitted to the modified Gompertz equation and the initial cell number (N-0), maximum cell number (N-max), maximum specific growth rate (mu(max)), lag-phase (lambda) of total psychrotrophic counts (TPC), lactic acid bacteria (LAB), Coliforms, Pseudomonads, Brochothrix thermosphacta, Salmonella, yeasts were obtained as derived parameters. Pseudomonades and Salmonella were predominant bacteria associated with spoilage of pork. Interaction coefficients (alpha) acquired from steady-state equation of the modified Lotka-Volterra model were used to describe the antagonistic activities of each pair of microorganisms. Yeasts and LAB had larger influences on Coliforms, Pseudomonads, Brochothrix thermosphacta and Salmonella than vice versa (alpha(12) < alpha(21)), and yeasts had high antimicrobial activity on LAB (alpha(12)(0.043) < alpha(21)(19.491)). However, the last four microorganisms showed little antagonistic activity. (c) 2004 Elsevier Ltd. All rights reserved.