Competition between Salmonella and Pseudomonas species growing in and on agar, as affected by pH, sodium chloride concentration and temperature

pH/sodium chloride (NaCl) gradient plates were used to investigate competition between Pseudomonas and Salmonella species. At 30 °C and at particular NaClpH conditions the salmonellae inhibited growth of P. fluorescens and not P. putida. At 20 °C P. putida and not P. fluorescens inhibited the salmonellae. The growth of the pure and mixed strains in agar plates with the pHNaCl conditions was compared by viable counts. Competition in pour plates at 30 °C was confirmed. At 20 °C, sub-surface growth of the salmonellae inhibited the P. putida. With surface growth this did not occur; the salmonellae was slightly inhibited by the P. putida.