Date of Award


Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy


Department of Biological Sciences

First Advisor

Dr. Olivia Mc Auliffe

Second Advisor

Dr. Kieran Jordan

Third Advisor

Dr. Aidan Coffey


In Agaricus bisporus production, the occurrence of L. monocytogenes is still poorly understood. A number of studies have shown the presence of L. monocytogenes in the mushroom processing environment, suggesting its source from raw materials storage areas (Viswanath et al, 2013; Murugesan et al, 2015). In this study, 10 mushroom producers and three raw material (compost and casing) producers participated in two surveys on the occurrence of L. monocytogenes in the most high-risk areas of the production environment. In the first survey, floors, drains, platforms, crates, raw materials and mushrooms were tested for L. monocytogenes presence and the results were used to recommend improvements in hygiene practices, with the aim of reducing occurrence and cross contamination in the mushroom production environment. The second survey was focused on the presence of L monocytogenes on food contact surfaces (compost and casing sampled during the mushroom production), raw materials and mushrooms. The results showed an overall L. monocytogenes occurrence of 32.1% and 5.7% on the mushrooms. In the casing, 16% of samples were positive, while in the compost, 7.4% were positive for L. monocytogenes. Chi square analysis of the data showed an association between the occurrence of L. monocytogenes in the casing soil, the processing environment and on the mushrooms, suggesting a cross contamination scenario. The results described in this chapter suggest that L. monocytogenes is naturally present in the raw materials used for mushroom growth, especially in the casing soil, and some improvements are needed in the hygiene practices commonly in use in the mushroom production, to reduce the risk of cross contamination on the mushrooms.


Research Supervisors:

Dr. Olivia McAuliffe and Dr. Kieran Jordan - Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland.

Dr. Aidan Coffey - Department of Biological Sciences, Cork Institute of Technology, Co. Cork, Ireland.

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