Potential for transfer of Escherichia coli O157:H7, Listeria monocytogenes and Salmonella Senftenberg from contaminated food waste derived compost and anaerobic digestate liquid to lettuce plants

• Published in: Food microbiology Vol. 59; pp. 7 - 13
• Main Authors: Murphy, Suzannah, Gaffney, Michael T., Fanning, Seamus, Burgess, Catherine M.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.10.2016
• Subjects: Anaerobic digestion; Anaerobiosis; Bacteria; Bacterial Load; Composting; Contaminated fertilisers; Contamination; Culture Media; Escherichia coli; Escherichia coli O157 - pathogenicity; Escherichia coli O157 - physiology; Escherichia coli O157 - ultrastructure; Fertilizers - microbiology; Food Microbiology; Foodborne pathogens; Foods; Humans; Lactuca - growth & development; Lactuca - microbiology; Lettuces; Liquids; Listeria monocytogenes; Listeria monocytogenes - pathogenicity; Listeria monocytogenes - physiology; Listeria monocytogenes - ultrastructure; Manure; Microbial Viability; Microscopy, Confocal; Plant uptake; Risk Assessment; Salmonella enterica - pathogenicity; Salmonella enterica - physiology; Salmonella enterica - ultrastructure; Salmonella senftenberg; Soil; Soil Microbiology; Wastes; Water Microbiology; Foodborne pathogens; Plant uptake; Contaminated fertilisers
• ISSN: 0740-0020; 1095-9998
• DOI: 10.1016/j.fm.2016.04.006

The diversion of food wastes from landfill to sustainable disposal methods, such as composting and anaerobic digestion, has led to an increase in the soil amendment products that are now commercially available and which are derived from both of these processes. The use of such products as soil amendments during the production of ready-to-eat (RTE) crops is increasing worldwide. The aim of this study was to investigate the potential of three well-recognised bacterial pathogens of importance to public health, namely Escherichia coli O157:H7, Salmonella Senftenberg and Listeria monocytogenes, to become internalised in lettuce plants from peat growing media amended with contaminated food waste derived compost and anaerobic digestion liquid. The results demonstrated both S. Senftenberg and E. coli O157:H7 are capable of internalisation at lower inoculation levels, compared to previous studies. The internalisation was visualised through confocal microscopy. Internalisation of L. monocytogenes did not occur, however significant levels of L. monocytogenes contamination occurred on the non-sterilised plant surface. Assessing the internalisation potential for each of these pathogens, through the compost and anaerobic digestate matrices, allows for better risk assessment of the use of these products in a horticultural setting. •Assessing internalisation potential of pathogens enables risk assessment in use of organic fertilisers for RTE crops.•Plant surface sterilisation techniques and GFP tagged bacterial isolates employed.•Both Salmonella Senftenberg and Escherichia coli O157:H7 were positive for internalisation at inoculation levels of Log105 CFU g−1.•Internalisation of Listeria monocytogenes was not observed.