Sheridan J J, Logue C M, McDowell D A, Blair I S, Hegarty T
National Food Centre, Teagasc, Dunsinea, Castleknock, Dublin, Ireland.
J Appl Microbiol. 1998 Aug;85(2):293-301. doi: 10.1046/j.1365-2672.1998.00504.x.
The growth kinetics of a virulence plasmid-bearing (P+) and a plasmid-cured (P-) strain of Yersinia enterocolitica serotype O:3 in pure and meat culture were investigated. Growth studies were carried out at 25 and 37 degrees C in supplemented phosphate-buffered saline, buffered peptone water, cefsulodin-irgasan-novobiocin broth base or supplemented broth base (CIN). The lag phase durations and growth rates under these conditions were determined by linear regression analysis. In pure culture, under most sets of equivalent conditions, P+ and P- strains had similar lag phase durations. However, under one set of conditions, i.e. CIN broth at 37 degrees C, the lag phase duration of the P+ strain was significantly longer than P-. In all but the most selective medium, P+ strains had slower growth rates that P- strains at 37 degrees C, probably due to the increase metabolic burden entailed in the maintenance of the virulence plasmid. In the most selective medium, i.e. CIN broth, P+ strains grew significantly faster than P-. This finding suggests that possession of virulence plasmid confers an enhanced ability to grow in the presence of selective agents. In meat cultures, both strains had longer lag phase than in equivalent pure cultures, with longer lag phases noted at 37 than at 25 degrees C. No significant differences were observed between the length of lag phases of P+ and P strains in meat culture. Both strains of Y. enterocolitica displayed faster growth rates in meat cultures than in pure cultures, indicating that one of more components of meat enhanced the growth of this organism. The effects and interaction of incubation temperature, enrichment broth and meat on the growth kinetics of plasmid-bearing and plasmid-cured Y. enterocolitica strains are discussed.
研究了肠炎耶尔森氏菌O:3血清型的携带毒力质粒（P +）菌株和质粒消除（P -）菌株在纯培养物和肉培养基中的生长动力学。在补充了磷酸盐缓冲盐水、缓冲蛋白胨水、头孢磺啶-伊曲康唑-新生霉素肉汤基础培养基或补充肉汤基础培养基（CIN）中，于25℃和37℃进行生长研究。通过线性回归分析确定这些条件下的延迟期持续时间和生长速率。在纯培养物中，在大多数等效条件下，P +和P -菌株的延迟期持续时间相似。然而，在一组条件下，即在37℃的CIN肉汤中，P +菌株的延迟期持续时间明显长于P -菌株。在除最具选择性的培养基外的所有培养基中，P +菌株在37℃时的生长速率比P -菌株慢，这可能是由于维持毒力质粒带来的代谢负担增加所致。在最具选择性的培养基即CIN肉汤中，P +菌株的生长明显快于P -菌株。这一发现表明，携带毒力质粒赋予了在选择性试剂存在下更强的生长能力。在肉培养基中，两种菌株的延迟期都比在等效的纯培养物中长，37℃时的延迟期比25℃时更长。在肉培养基中，P +和P -菌株的延迟期长度没有显著差异。肠炎耶尔森氏菌的两种菌株在肉培养基中的生长速率都比在纯培养物中快，这表明肉中的一种或多种成分促进了该生物体的生长。讨论了培养温度、富集肉汤和肉对携带质粒和消除质粒的肠炎耶尔森氏菌菌株生长动力学的影响及相互作用。
