Diversity of the microflora of edible macroalga (Palmaria palmata)

Edible seaweed (Palmaria palmata) has traditionally been consumed raw after harvesting from coastal shorelines around Northern Ireland. To date, there have been no reports examining the microbiology of this material, hence it was the aim of this study to detect the diversity of the microflora found on ready-to-eat produce. Conventional microbiological analyses of the product failed to detect any gastrointestinal pathogens and gave a mean total count of 1·3×105 cfu g−1. 16S rRNA sequencing of culturable bacteria identified theSanguibacter/Oerskovia/Cellulomonas complex, the Clavibacter/Frigoribacterium/Curtobacterium complex, Enterobacter agglomerans, Erwinia herbicola, Flavobacterium spp., Micrococcus lylae,Microbacterium spp., Corynebacterium spp., and Dietza maris. A comparison of growth of isolated environmental organisms was performed to ascertain the most appropriate artificial culture media to employ for their culture in vitro. Tryptone soya broth with yeast extract (TSBYE) and brain–heart infusion broth with yeast extract (BHIYE) may be employed as suitable basal broth media for the laboratory culture of these organisms. This is the first preliminary report on the microbial diversity of edible seaweed and demonstrated the presence of several halophilic genera and species in fresh ready-to-eat edible seaweed from Northern Ireland. Although no gastrointestinal pathogens were cultured from this material, a larger study requiring examination of seasonal effects, quality of marine water and effect of drying on faecal pathogens, is required to support a functional HACCP-based approach to ensuring safety of this product.