Plant Research International BV, Wageningen University and Research Centre, Wageningen, the Netherlands.
Lett Appl Microbiol. 2010 Apr;50(4):425-30. doi: 10.1111/j.1472-765X.2010.02817.x. Epub 2010 Feb 4.
The survival capability of pathogens like Escherichia coli O157:H7 in manure-amended soil is considered to be an important factor for the likelihood of crop contamination. The aim of this study was to reveal the effects of the diversity and composition of soil bacterial community structure on the survival time (ttd) and stability (irregularity, defined as the intensity of irregular dynamic changes in a population over time) of an introduced E. coli O157:H7 gfp-strain were investigated for 36 different soils by means of bacterial PCR-DGGE fingerprints.
Bacterial PCR-DGGE fingerprints made with DNA extracts from the different soils using bacterial 16S-rRNA-gene-based primers were grouped by cluster analysis into two clusters consisting of six and 29 soils and one single soil at a cross-correlation level of 16% among samples per cluster. Average irregularity values for E. coli O157:H7 survival in the same soils differed significantly between clusters (P = 0.05), whereas no significant difference was found for the corresponding average ttd values (P = 0.20). The irregularity was higher for cluster 1, which consisted primarily of soils that had received liquid manure and artificial fertilizer and had a significant higher bacterial diversity and evenness values (P < 0.001).
Bacterial PCR-DGGE fingerprints of 36 manure-amended soils revealed two clusters which differed significantly in the stability (irregularity) of E. coli O157 decline. The cluster with the higher irregularity was characterized by higher bacterial diversity and evenness.
The consequence of a high temporal irregularity is a lower accuracy of predictions of population behaviour, which results in higher levels of uncertainty associated with the estimates of model parameters when modelling the behaviour of E. coli O157:H7 in the framework of risk assessments. Soil community structure parameters like species diversity and evenness can be indicative for the reliability of predictive models describing the fate of pathogens in (agricultural) soil ecosystems.
像大肠杆菌 O157:H7 这样的病原体在施肥土壤中的生存能力被认为是作物污染可能性的一个重要因素。本研究的目的是揭示土壤细菌群落结构多样性和组成对引入的大肠杆菌 O157:H7 gfp 株的生存时间 (ttd) 和稳定性 (不规则性，定义为种群随时间不规则动态变化的强度) 的影响，为此，通过细菌 PCR-DGGE 指纹图谱对 36 种不同土壤进行了研究。
用基于细菌 16S-rRNA 基因的引物从不同土壤中提取 DNA 提取物，用细菌 PCR-DGGE 指纹图谱进行分析，然后通过聚类分析将其分为两个聚类，每个聚类包含 6 个和 29 个土壤样本，以及一个单独的土壤样本，聚类之间的样本相关性为 16%。在同一土壤中大肠杆菌 O157:H7 存活的不规则性平均值在聚类之间存在显著差异（P = 0.05），而相应的平均 ttd 值则无显著差异（P = 0.20）。聚类 1 中的不规则性较高，主要由接受液体肥料和人工肥料的土壤组成，其细菌多样性和均匀度值显著较高（P < 0.001）。
36 种施肥土壤的细菌 PCR-DGGE 指纹图谱显示，大肠杆菌 O157 下降稳定性（不规则性）存在两个显著差异的聚类。不规则性较高的聚类具有较高的细菌多样性和均匀度。
时间不规则性高的后果是对种群行为预测的准确性降低，这导致在使用模型模拟大肠杆菌 O157:H7 在风险评估框架中的行为时，与模型参数估计相关的不确定性水平更高。土壤群落结构参数，如物种多样性和均匀度，可以作为预测模型描述（农业）土壤生态系统中病原体命运的可靠性的指标。
