Department of Food Science and Post Harvest Technology, Gulu University, Uganda.
Int J Food Microbiol. 2011 Sep 15;149(2):133-42. doi: 10.1016/j.ijfoodmicro.2011.06.009. Epub 2011 Jun 25.
The effect of cabbage (Brassica oleracea) rhizosphere on survival of Escherichia coli O157:H7 and Salmonella Typhimurium in manure-amended soils under tropical field conditions was investigated in the Central Agro-Ecological Zone of Uganda. Three-week old cabbage seedlings were transplanted and cultivated for 120 days on manure-amended soil inoculated with 4 or 7 log CFU/g non-virulent E. coli O157:H7 and S. Typhimurium. Cabbage rhizosphere did not affect survival of the 4log CFU/g inocula in manure-amended soil and the two enteric bacteria were not detected on/in cabbage leaves at harvest. The 7 log CFU/g E. coli O157:H7 and S. Typhimurium survived in bulk soil for a maximum of 80 and 96 days, respectively, but the organisms remained culturable in cabbage rhizosphere up to the time of harvest. At 7 log CFU/g inoculum, E. coli O157:H7 and S. Typhimurium contamination on cabbage leaves occurred throughout the cultivation period. Leaf surface sterilisation with 1% AgNO(3) indicated that the organisms were present superficially and in protected locations on the leaves. These results demonstrate that under tropical field conditions, cabbage rhizosphere enhances the persistence of E. coli O157:H7 and S. Typhimurium in manure-amended soil at high inoculum density and is associated with long-term contamination of the leaves.
在乌干达中央农业生态区，研究了白菜（甘蓝型油菜）根际对肥料添加土壤中大肠杆菌 O157:H7 和鼠伤寒沙门氏菌存活的影响。将 3 周龄的白菜幼苗移栽并在接种 4 或 7 log CFU/g 非毒性大肠杆菌 O157:H7 和鼠伤寒沙门氏菌的肥料添加土壤上培养 120 天。白菜根际对肥料添加土壤中 4log CFU/g 接种物的存活没有影响，在收获时也没有在白菜叶上检测到这两种肠道细菌。7 log CFU/g 的大肠杆菌 O157:H7 和鼠伤寒沙门氏菌在基础土壤中的存活时间最长分别为 80 天和 96 天，但在收获时仍可在白菜根际中培养。在 7 log CFU/g 接种物的情况下，大肠杆菌 O157:H7 和鼠伤寒沙门氏菌污染了整个白菜叶片的生长周期。用 1%AgNO(3)对叶片表面进行消毒表明，这些生物体存在于叶片的表面和受保护的位置。这些结果表明，在热带田间条件下，白菜根际在高接种密度下增强了肥料添加土壤中大肠杆菌 O157:H7 和鼠伤寒沙门氏菌的持久性，并与叶片的长期污染有关。
