Experimental evaluation of survival of Vibrio parahaemolyticus in fertilized cold-water sediment.

Abstract

This experimental study focuses on survival and consistence of Vibrio parahaemolyticus in cold-water sediments and how increasing temperature and nutritional availability can affect growth. A pathogenic strain of V. parahaemolyticus was inoculated in seawater microcosms containing bottom sediment. Gradually, during 14days, the temperature was upregulated from 8 to 21°C. Culturable V. parahaemolyticus was only found in the sediment but declined over time and did not recover even after another 2days at 37°C. Numbers of culturable bacteria matched the amount found by q-PCR indicating that they did not enter a dormant state, contrary to those in the water layer. After adding decaying phytoplankton as fertilizer to the microcosms of 8 and 21°C for 7 and 14days, the culturability of the bacteria increased significantly in the sediments at both temperatures and durations of exposure. The study showed that V. parahaemolyticus can stay viable in cold-water sediment and growth was stimulated by fertilizers rather than by temperature. Vibrio parahaemolyticus is a common cause of seafood-borne gastroenteritis and is today recognized in connection to increasing ocean temperature. The results indicate that this pathogen should be considered a risk in well-fertilized environments, such as aquacultures, even during cold periods.