title: Rhizosphere effect on survival of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium in manure-amended soil during cabbage (Brassica oleracea) cultivation under tropical field conditions in Sub-Saharan Africa.
abstract: 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.
authors: Department of Food Science and Post Harvest Technology, Gulu University, Uganda. duncanongeng@hotmail.com
authors: Duncan
authors: D
authors: Ongeng
authors: Charles
authors: C
authors: Muyanja
authors: Jaak
authors: J
authors: Ryckeboer
authors: Annemie H
authors: AH
authors: Geeraerd
authors: Dirk
authors: D
authors: Springael
mesh_terms: D000383:Agriculture; D001937:Brassica / Q000254:growth & development* / Q000382:microbiology; D015169:Colony Count, Microbial; D019453:Escherichia coli O157 / Q000254:growth & development* / Q000302:isolation & purification; D008372:Manure / Q000382:microbiology; D018515:Plant Leaves / Q000382:microbiology; D058441:Rhizosphere; D012486:Salmonella typhimurium / Q000254:growth & development* / Q000302:isolation & purification; D012988:Soil Microbiology; D014329:Tropical Climate; D014454:Uganda
chemical_list: D008372:Manure