Food associated indigenous microbial communities exert antagonistic effects on pathogens and may routinely deliver health relevant microorganisms to the GI tract. By using molecular, culture independent methods including PCR-DGGE of 16S rDNA-coding regions and real-time PCR (RT-PCR) as well as BIOLOG metabolic fingerprinting, microbial communities on lettuce were analyzed in samples from fields, from supermarkets and soil. Amplified 16S rRNA gene sequences (57.7%) could be assigned to species previously reported as typical for the phyllosphere including Pantoea agglomerans, Pseudomonas flavescens, Moraxella spp., and Mycobacterium spp. 71.8% of the sequences obtained represented so far undescribed taxa. Principal component analysis of BIOLOG metabolic profiles indicated a seasonal variation in the lettuce phyllosphere microbial community structure. Various lactic acid bacteria were detected including several Lactobacillus and Leuconostoc species in particular on lettuce from organic farming. By RT-PCR lactobacilli were found with a range of abundances from 1x10(4 )to 1x10(5 )copies/g lettuce. Considering the importance of salad in many diets lettuce may contribute to a constant supply with LAB.