Vibrio parahaemolyticus Population and Microbial Community Dynamics Related to Post-Harvest Oyster Relay Success

Oysters harbor Vibrio parahaemolyticus (Vp) in warm coastal waters. With recent changing climate conditions, a public health problem in the Northeast US has emerged as pathogenic Vp strains have become more prevalent in... [ view full abstract ]

Oysters harbor Vibrio parahaemolyticus (Vp) in warm coastal waters. With recent changing climate conditions, a public health problem in the Northeast US has emerged as pathogenic Vp strains have become more prevalent in regional oysters. Oysters with elevated Vp levels were relayed from the Great Bay estuary to Spinney Creek with low Vp abundance for fourteen days. Relay experiments were run to assess the potential success of relaying, and the microbial community composition was analyzed to determine if community changes during relaying correlate with Vp reduction to help explain the success of relaying. Vp levels were determined using 3-tube MPN enrichment with genetic marker (tlh) qPCR. Taxa compositions of day 0 and 14 relay water and oyster samples were determined using 16S rRNA gene sequences and Illumina HiSeq sequencing. Sequence relative abundance for sample OTUs was organized by consensus lineage for comparison of taxa compositions in relay samples. Oyster and water microbiome taxa were statistically different, yet oyster microbiomes consistently changed to significantly different taxa when relay was successful. When relaying was unsuccessful in 2013, day 0 taxa were different from other year day 0 taxa, and either did not change with relaying or changed to a unique array of taxa. In relayed oysters with the largest Vp reductions, 33 out of 365 identified genera increased in relative abundance, including Vibrio, Corynebacterium, Mycoplasma, Phaeobacter, and Shewanella species. Ensuing experiments informed by these results suggest competition as a potential mechanism for how relaying reduces Vp levels.