Semenov Alexander V, van Bruggen Ariena H C, van Overbeek Leo, Termorshuizen Aad J, Semenov Alexander M
Biological Farming Systems Group, Wageningen University and Research Center, Department of Plant Sciences, Wageningen, The Netherlands.
FEMS Microbiol Ecol. 2007 Jun;60(3):419-28. doi: 10.1111/j.1574-6941.2007.00306.x. Epub 2007 May 8.
The effects of four average temperatures (7, 16, 23 and 33 degrees C) and daily oscillations with three amplitudes (0, +/-4, +/-7 degrees C) on the survival of the enteropathogens Escherichia coli O157:H7 and Salmonella serovar Typhimurium were investigated in small microcosms. Manure was inoculated with a green fluorescent protein transformed strain of either pathogen at 10(7) cells g(-1) dry weight. Samples were collected immediately after inoculation, and 1 and 2 weeks after inoculation for E. coli O157:H7, and immediately and after 2 and 3 weeks for Salmonella serovar Typhimurium. Population densities were determined by dilution plating and direct counting. In addition, total bacterial CFUs were determined. Growth and survival data were fitted to a modified logistic model. Analysis of the estimated parameter values showed that E. coli O157:H7 survived for shorter periods of time and was more sensitive to competition by the native microbial community than Salmonella serovar Typhimurium. Survival of both pathogens significantly declined with increasing mean temperatures and with increasing amplitude in daily temperature oscillations. The results indicated that responses of enteropathogens to fluctuating temperatures cannot be deduced from temperature relationships determined under constant temperatures.
在小型微观世界中，研究了四种平均温度（7、16、23和33摄氏度）以及三种振幅（0、±4、±7摄氏度）的每日温度振荡对肠道致病菌大肠杆菌O157:H7和鼠伤寒沙门氏菌存活的影响。用10⁷个细胞每克干重的绿色荧光蛋白转化的两种致病菌菌株之一接种粪便。接种后立即以及接种大肠杆菌O157:H7后的1周和2周，以及接种鼠伤寒沙门氏菌后的立即、2周和3周采集样本。通过稀释平板计数和直接计数确定菌量密度。此外，还测定了总细菌菌落形成单位。生长和存活数据拟合到一个修正的逻辑模型。对估计参数值的分析表明，与鼠伤寒沙门氏菌相比，大肠杆菌O157:H7存活时间更短，并且对本地微生物群落的竞争更敏感。两种致病菌的存活率均随平均温度升高和每日温度振荡幅度增大而显著下降。结果表明，不能从恒温条件下确定的温度关系推断肠道致病菌对温度波动的反应。
