2014 ASHS Annual Conference

The Municipal Sludge Compost (MSC)it has been used as an alternate growing media for peat and as amendment in agricultural soil. There is much skepticism for the use of MSC as substratum in fresh edible crops. Consumers has the understanding that vegetables grown in this substratum could contain human pathogenic microorganisms. Microorganisms such as, Escherichia coli and Salmonella spp, have the capacity to be transported through the interior of the plant and be found in crop tissues. There was a need to conduct research on this particular issue. The main objective of this study was to determine the presence or absence of coliforms bacteria, E. coli and Salmonella spp. in lettuce plant tissues. Three treatments were evaluated, in which lettuce was grown in MSC (100), Peat (100) and a mix of MSC: Peat (25:75).These treatment, were evaluated previously on ornamental crops. The methodology used to detect the presence of coliforms bacteria, were, through Membrane Filtration, by using Colilert® test and TECRA® Salmonella detection analysis. Lettuces plants were harvested 40 days after planted. Results shown, the presence of coliforms in all tissues of lettuce plants. None colonies of E. coli and Salmonella spp.were identified on any treatment. The highest number of coliform colonies were found in treatment MSC:Peat (25:75). By using BIOLOG® tests, different coliform bacteria were identified, Enterobacter sakazakii  were found in the lettuce grown in MSC, Pantoea dispersa grown in Peat and P. dispersa, P. agglomerans and Pseudomonas mendocina in the MSC: Peat mix. These coliforms bacteria are considered opportunistic pathogens to humans.