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首页> 外文期刊>Applied Microbiology >Determining Thermal Inactivation of Escherichia coli O157:H7 in Fresh Compost by Simulating Early Phases of the Composting Process
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Determining Thermal Inactivation of Escherichia coli O157:H7 in Fresh Compost by Simulating Early Phases of the Composting Process

机译：通过模拟堆肥过程的早期阶段来确定新鲜堆肥中大肠杆菌O157：H7的热失活

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A three-strain mixture of Escherichia coli O157:H7 was inoculated into fresh dairy compost (ca. 10~(7) CFU/g) with 40 or 50% moisture and was placed in an environmental chamber (ca. 70% humidity) that was programmed to ramp from room temperature to selected composting temperatures in 2 and 5 days to simulate the early composting phase. The surviving E. coli O157:H7 population was analyzed by direct plating and enrichment. Optimal and suboptimal compost mixes, with carbonitrogen (C/N) ratios of 25:1 and 16:1, respectively, were compared in this study. In the optimal compost mix, E. coli O157:H7 survived for 72, 48, and 24 h in compost with 40% moisture and for 72, 24, and 24 h with 50% moisture at 50, 55, and 60°C, respectively, following 2 days of come-up time (rate of heating up). However, in the suboptimal compost mix, the pathogen survived for 288, 72, and 48 h in compost with 40% moisture and for 240, 72, 24 h in compost with 50% moisture at the same temperatures, respectively. Pathogen survival was longer, with 5 days of come-up time compared with 2 days of come-up. Overall, E. coli O157:H7 was inactivated faster in the compost with 50% moisture than in the compost with 40% at 55 and 60°C. Both moisture and come-up time were significant factors affecting Weibull model parameters. Our results suggest that slow come-up time at the beginning of composting can extend pathogen survival during composting. Additionally, both the C/N ratio and the initial moisture level in the compost mix affect the rate of pathogen inactivation as well.
机译：将三株大肠杆菌O157：H7的混合物接种到含水量为40％或50％的新鲜乳制品堆肥（约10〜（7）CFU / g）中，并置于环境箱（湿度约70％）中，程序被设置为在2到5天内从室温升至选定的堆肥温度，以模拟早期堆肥阶段。通过直接铺板和富集分析了存活的大肠杆菌O157：H7群体。在这项研究中，比较了最佳堆肥和次最佳堆肥混合物，分别具有25：1和16：1的碳/氮（C / N）比。在最佳的堆肥混合物中，大肠杆菌O157：H7在50％的湿度，50％，55和60°C的湿度下在堆肥中存活72、48和24小时，在50％的湿度下存活72、24和24小时，分别在接下来的2天上床时间（升温速度）下进行。但是，在次优堆肥中，在相同温度下，病原体在含40％水分的堆肥中存活288、72和48小时，在含50％水分的堆肥中存活240、72、24小时。病原体存活时间更长，随访时间为5天，而随访时间为2天。总体而言，在55和60°C下，含水量为50％的堆肥中的O157：H7大肠杆菌的失活速度要快于含水量为40％的堆肥中的大肠杆菌。水分和上浮时间都是影响威布尔模型参数的重要因素。我们的结果表明，堆肥开始时较慢的浮出时间可以延长堆肥期间病原体的存活时间。另外，堆肥混合物中的C / N比和初始水分含量也会影响病原体失活的速率。

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