Logue C M, Sherwood J S, Doetkott C
The Great Plains Institute of Food Safety, Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, ND 58105, USA.
J Appl Microbiol. 2006 Jun;100(6):1299-306. doi: 10.1111/j.1365-2672.2006.02861.x.
In this study, the growth characteristics of Yersinia enterocolitica biotype 4, GER O:3 plasmid bearing (P+) and plasmid cured (P-) strain types were evaluated in brain heart infusion broth supplemented with cefsulodin, irgasan, and novobiocin alone or in combination.
Growth curves were obtained for the two strain types in broth supplemented with selective agents at 25 or 37 degrees C for 32 h to obtain data on the lag phase durations and growth rates of the strains. Generally, the lag times and growth rates of the P+ and P- strains were similar for cultures incubated at 25 degrees C regardless of the selective agent added and where plasmid replication and expression were not under any significant burden. However, where the lag times and growth rates of the strains were examined at 37 degrees C, significant differences were observed in the lag phase durations of the plasmid bearing strain type compared the plasmid cured strain, an effect that was due to the burden of the plasmid and the influence of selective agents. Generally, when two or more agents were present, lag phase durations were longer for the plasmid bearing strain. Some exceptions noted where in the presence of irgasan or full selective agent (CIN) the opposite case was observed. When growth rates were compared, the plasmidless strain type was typically faster than the plasmid bearing strain in the presence of most selective agents at 37 degrees C and the growth rates of both strain types at 25 degrees C were similar where the temperature appeared to negate the effects of plasmid.
The data obtained in these studies suggest that selective agents (in particular irgasan) and incubation temperature play a significant role in influencing the growth characteristics of plasmid bearing and plasmid cured strains of Y. enterocolitica.
This data presented in this study has significant implications for enrichment methods used in the detection or recovery of plasmid bearing Y. enterocolitica strains from food, environmental or clinical samples.
在本研究中，评估了小肠结肠炎耶尔森菌生物4型、携带GER O:3质粒（P+）和质粒消除（P-）菌株类型在单独或联合添加头孢磺啶、氯己定碘和新生霉素的脑心浸液肉汤中的生长特性。
在添加了选择剂的肉汤中，于25或37℃培养两种菌株类型32小时，以获得关于菌株延滞期持续时间和生长速率的数据。一般来说，在25℃培养时，无论添加何种选择剂，且质粒复制和表达未承受任何显著负担的情况下，P+和P-菌株的延滞时间和生长速率相似。然而，在37℃检测菌株的延滞时间和生长速率时，与质粒消除菌株相比，携带质粒的菌株类型在延滞期持续时间上存在显著差异，这是由于质粒负担和选择剂的影响所致。一般来说，当存在两种或更多种试剂时，携带质粒的菌株的延滞期持续时间更长。在某些例外情况下，在氯己定碘或完全选择剂（CIN）存在时，观察到相反的情况。当比较生长速率时，在37℃存在大多数选择剂的情况下，无质粒菌株类型通常比携带质粒的菌株生长得更快，并且在25℃时两种菌株类型的生长速率相似，此时温度似乎抵消了质粒的影响。
这些研究中获得的数据表明，选择剂（特别是氯己定碘）和培养温度在影响小肠结肠炎耶尔森菌携带质粒和质粒消除菌株的生长特性方面起着重要作用。
本研究中呈现的数据对于从食品、环境或临床样本中检测或回收携带质粒的小肠结肠炎耶尔森菌菌株所使用的富集方法具有重要意义。
