Key Laboratory of Ground Water Resource and Environment, Ministry of Education, Jilin University, Changchun 130021, China; Jilin Provincial Key Laboratory of Water Resources and Environment, Jilin University, Changchun 130021, China; State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Ground Water Resource and Environment, Ministry of Education, Jilin University, Changchun 130021, China.
Sci Total Environ. 2020 Dec 20;749:141649. doi: 10.1016/j.scitotenv.2020.141649. Epub 2020 Aug 12.
Soil physicochemical properties and microbial community have been proved to be correlated to survival behaviors of Shiga toxin-producing Escherichia coli O157:H7, but the roles of biotic and abiotic factors in the different stages of inactivation process remain unclear. Here, fruit producing soils were collected, and soils physicochemical properties, bacterial and fungal community structure were characterized. Survival experiments were performed by inoculating E. coli O157:H7 in soils. Double Weibull survival model was found to better fit the experimental data, and two subpopulations with different capability on resistance to stress were identified. The sensitive subpopulation with smaller δ (time needed for first decimal reduction) (i.e., δ) died off faster compared to the more resistant subpopulation with greater δ (i.e., δ). Partial Mantel test revealed that ttd (time needed to reach detection limit) was jointly influenced by physical factors, chemical factors, and bacterial composition (P < 0.05); δ was shaped by physical factors (P < 0.01) and additional bacterial composition (P < 0.05); and δ was strongly steered by bacterial community (P < 0.001). Bacterial co-occurrence network analysis revealed that samples with lower δ were coupled with higher network complexity and closer taxa relationship (e.g. higher average (weighted) degree, higher network diameter, higher graph density, and lower modularity), and vice versa. Taken together, the sensitive subpopulation had difficulty in adapting to coarse particles conditions, while resistant subpopulation might eventually succumb to the robust biodiversity. This study provides novel insights into the E. coli O157:H7 survival mechanism through subpopulation perspective and sheds light on the reduction of edaphic colonization by pathogens via agricultural management strategy.
土壤理化性质和微生物群落已被证明与产志贺毒素大肠杆菌 O157:H7 的存活行为相关，但生物和非生物因素在失活动力学的不同阶段的作用仍不清楚。本研究采集了产果土壤，分析了土壤理化性质、细菌和真菌群落结构。通过将大肠杆菌 O157:H7 接种到土壤中进行存活实验。结果发现，双 Weibull 生存模型更适合实验数据，并且鉴定出了具有不同抗应激能力的两个亚群。敏感亚群的 δ（第一个十进制减少所需的时间）较小，比具有较大 δ（即 δ）的更具抗性的亚群死亡更快。偏Mantel 检验表明，ttd（达到检测限所需的时间）受物理因素、化学因素和细菌组成的共同影响（P<0.05）；δ由物理因素（P<0.01）和附加细菌组成（P<0.05）决定；而 δ则受细菌群落的强烈影响（P<0.001）。细菌共生网络分析表明，δ值较低的样本与更高的网络复杂性和更密切的分类群关系相关（例如，更高的平均（加权）度、更高的网络直径、更高的网络密度和更低的模块性），反之亦然。综上所述，敏感亚群难以适应粗颗粒条件，而抗性亚群最终可能会因强大的生物多样性而屈服。本研究从亚群角度为大肠杆菌 O157:H7 的存活机制提供了新的见解，并为通过农业管理策略减少土壤定植病原体提供了启示。
