GROWTH-RATE AND PHYSIOLOGY OF YERSINIA-ENTEROCOLITICA INFLUENCE OF TEMPERATURE AND PRESENCE OF THE VIRULENCE PLASMID

The effect of temperature on the growth rate, protein pattern and fatt y acid composition of Yersinia enterocolitica strain W22703 pYV(+), it s plasmidless isogenic derivative W22703 pYV(-) and four recent field isolates was examined. The growth rate was clearly influenced by prese nce or absence of the virulence plasmid: pYV(-) strains grew consisten tly faster than pYV(+) strains. This difference in growth rate was hig h at 30-35 degrees C, moderate at 1-10 degrees C and 25 degrees C, but hardly significant at 15-20 degrees C. Increasing the growth temperat ure above 25 degrees C resulted in the induction of the 220 kDa virule nce plasmid-encoded Yop1 protein. In the 1-20 degrees C range no obvio us temperature- or plasmid-related differences in protein patterns cou ld be detected. The fatty acid composition showed a clear temperature- dependent change: with all strains the degree of saturation was low at 1 degrees C and gradually increased with raising temperatures. All st rains had similar fatty acid patterns, except one of the field isolate s which showed aberrant C16:1 and cyclic fatty acid contents in the 5- 25 degrees C and less than or equal to 15 degrees C ranges respectivel y. With strain W22703, the presence or absence of the virulence plasmi d did not significantly alter the fatty acid pattern.