Hindawi Publishing Corporation Journal of Biomedicine and Biotechnology Volume 2009, Article ID 184130, 7 pages doi:10.1155/2009/184130 Research Article Modelling the Survival of Escherichia coli O157:H7 on Raw Portioned Tomatoes, Inoculated with Aspergillus fumigatus and Emericella nidulans Daniela Cardillo, 1 Antonio Bevilacqua, 1 Francesca Cibelli, 2 Clelia Altieri, 1 and Milena Sinigaglia 1 1 Department of Food Science, Faculty of Agricultural Science, Foggia University, Via Napoli 25, 71100 Foggia, Italy 2 Department of Agro-Environmental Science, Chemistry and Crop Protection, Faculty of Agricultural Science, Foggia University, Via Napoli 25, 71100 Foggia, Italy Correspondence should be addressed to Antonio Bevilacqua, a.bevilacqua@unifg.it Received 5 March 2009; Revised 2 July 2009; Accepted 23 September 2009 Recommended by Lori Snyder The metabiotic interactions occurring among two fungi (Aspergillus fumigatus and Emericella nidulans) and Escherichia coli O157:H7 on raw portioned tomatoes were studied. Tomatoes, preinoculated with the moulds and inoculated with the pathogen, were packaged in air and stored at 4, 8 and 12 ◦ C for 9 days; pathogen cell number and pH were monitored throughout the storage and the data were modeled using three different equations (Geeraerd, Weibull, and modified Weibull), to assess the shoulder length, the 1-log reduction time, and the death time. Both A. fumigatus and E. nidulans increased the survival of E. coli O157:H7 through the prolongation of the shoulder length; in contrast, the death time was significantly increased. The results of this paper suggested that the metabiotic interactions aspergilli/E. coli O 157:H7 could be of public concern, as the consumption of tomatoes (or other fruits and vegetables) contaminated both by the moulds and the pathogen is a possible scenario. Copyright © 2009 Daniela Cardillo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1. Introduction It is well known that fruits and vegetables can be con- taminated with foodborne pathogens, as a result of either preharvest contact with contaminated irrigation water or manure, or postharvest contamination due to incorrect harvesting, washing, minimal processing, distribution, and preparation in foodservice settings or at home [1]. Moulds of the genera Alternaria, Botrytis, Cladosporium, Fusarium, Rhizoctonia, and Rhizopus and some aspergilli are responsible for postharvest decay of fruits and vegetables [2–4]. The term metabiosis describes the reliance by an organ- ism on another to produce a favourable environment [5]; this can be the removal of oxygen by Gram-negative microflora, allowing the growth of anaerobic microorganisms, like Clostridium botulinum [5], or it can be situations where one organism provides nutrients enhancing growth of another [5]. Since 1980s many researchers have shown that a metabi- otic interaction could occur between moulds and pathogens, with a benefit for the latter, due to the production of some alkalinising compounds [2, 6], and evidence regarding interactions between moulds and bacteria on tomatoes is available [3, 4]. For example, Wade and Beuchat [4] observed that A. alternata and Cladosporium spp., coinoculated with Salmonella into raw ripe tomatoes, increased the pH of pulp, resulting in an enhancement of the rate of growth of the pathogen. Regarding the interaction moulds-psychrotrophic pathogens on minimally processed fruit, Riordan et al. [7] reported that Glomerella cingulata enhanced the survival of Escherichia coli O157:H7 on ready-to-use apples. In a previous research, Fusarium spp. (F. avenaceum, F. proliferatum and F. oxysporum) were shown to exert a metabiotic effect on E. coli O157:H7 on raw portioned toma- toes, but not on Listeria monocytogenes [8]. The metabiotic effect, however, was not due to an increase of pH of fruit, as