Regardless, analysis of store bought vegetables more truly represents what microorganisms are likely to be consumed by the typical consumer.

A recent study examining store bought lettuce found that 38 out of 100 leaves had internalized bacteria; although this conclusion was based solely on culture-dependent methods [39]. A few other studies have used pyrosequencing to analyse the phyllosphere bacterial BIX 1294 community on lettuce and spinach [19, 25, 26], although those studies buy AC220 retrieved the phyllosphere community from washes from leaves and thus exclude endophytes, as well as any bacteria that adhere tightly to the leaf surface. We used a different approach, in which we surface-sterilized the surface, killing the bacterial populations associated with the leaf surface. Thus our non-sterilized samples include all leaf-associated populations (endophytes and surface-associated), while our surface sterilized samples represent just the endophytes. To our knowledge, the study presented here is the first report of pyrosequencing analysis of the endophytic bacterial community associated with check details store bought, ready-to-eat produce. Conclusions Commercial ready-to-eat salad leaf vegetables

harbor an array of endophytic and surface associated bacteria. Culture-independent analysis using pyrosequencing indicated that the majority of leaf vegetable-associated bacteria were members of the Proteobacteria and Bacteroidetes. Dominant bacterial taxa identified by pyrosequencing were also identified as culturable isolates. However, the use of pyrosequencing also allowed for the identification of numerous low abundance bacteria that would not have been identified otherwise

by culture dependent methods. Whether vegetables were cultivated under conventional or organic agricultural systems appeared to have little consistent impact on the microbial community composition. While surface sterilization significantly decreased the number of bacteria, surface sterilized salad vegetables still contained at least 2.2 × 103 to 5.8 × 105 culturable endophytic cells per gram of leaf material. Even the most extreme washing would not remove these cells, so that consumers are constantly exposed to appreciable levels of plant-associated microorganisms. 3-mercaptopyruvate sulfurtransferase Methods Sample collection and processing Packages of ready-to-eat leaf vegetables were purchased from a grocery store in Oxford, Mississippi, USA, during September and October 2010. Leaf vegetables consisted of romaine lettuce and baby spinach (both purchased September 15th 2010), and green leaf lettuce, iceberg lettuce, and red leaf lettuce (all purchased October 11th 2010). Both organic and conventionally grown varieties of each produce type were obtained (ten samples total). Samples were in modified atmosphere packaging, stored in the chilled produce section.