Abstract：
Cover crops are plants seeded before or after cash crops to improve soil health, reduce weed pressure, and prevent erosion. Cover crops also produce various antimicrobial secondary metabolites (i.e., glucosinolates, quercetin), yet the role of cover crops in moderating the population of human pathogens in the soil has rarely been investigated. This study aims to determine the antimicrobial capacity of three cover crop species to reduce the population of generic Escherichia coli (E. coli) in contaminated agricultural soil. Four-week-old mustard greens (Brassicajuncea), sunn hemp (Crotalaria juncea), and buckwheat (Fagopyrum esculentum) were mixed into autoclaved soil and inoculated with rifampicin-resistant generic E. coli to achieve a starting concentration of 5 log CFU/g. The surviving microbial populations on days 0, 4, 10, 15, 20, 30, and 40 were enumerated. All three cover crops significantly reduced the population of generic E. coli compared to the control (p < 0.0001), particularly between days 10 and to 30. Buckwheat resulted in the highest reduction (3.92 log CFU/g). An inhibitory effect (p < 0.0001) on microbial growth was also observed in soils containing mustard greens and sunn hemp. This study provides evidence for the bacteriostatic and bactericidal effect of particular cover crops. More research regarding the secondary metabolites produced by certain cover crops and their potential as a bio mitigation strategy to improve on-farm produce safety is warranted.
摘要：
覆盖作物是在经济作物之前或之后播种以改善土壤健康的植物，降低杂草压力，防止侵蚀。覆盖作物还产生各种抗微生物次生代谢产物(即，芥子油苷,槲皮素)，然而，很少研究覆盖作物在调节土壤中人类病原体种群中的作用。本研究旨在确定三种覆盖作物的抗菌能力，以减少通用大肠杆菌的种群（E。大肠杆菌)在受污染的农业土壤中。四周龄的芥菜（Brassicajocea），太阳大麻（角克罗利亚），和荞麦(苦参)被混合到高压灭菌的土壤中并接种利福平抗性的通用大肠杆菌以达到5logCFU/g的起始浓度。对第0、4、10、15、20、30和40天存活的微生物群体进行计数。与对照相比，所有三种覆盖作物均显着减少了普通大肠杆菌的种群（p<0.0001），特别是在第10天到第30天之间。荞麦导致最高的降低(3.92logCFU/g)。在含有芥菜和大麻的土壤中也观察到对微生物生长的抑制作用（p<0.0001）。这项研究为特定覆盖作物的抑菌和杀菌作用提供了证据。有必要对某些覆盖作物产生的次生代谢产物及其作为改善农产品安全性的生物缓解策略的潜力进行更多研究。
