VIBRIO TRENDS IN THE ECOLOGY OF VENICE LAGOON

Vibrio is a very diverse genus responsible for different human and animal diseases. The accurate identification of Vibrio at the species level is important to assess the risks related to public health and diseases of aquatic organisms. The ecology of Vibrio spp., together with their genetic background, represents an important key for species discrimination and evolution. Thus, analyses of population structure and ecology association are necessary for reliable characterisation of bacteria and to investigate whether bacterial species are going through adaptation processes. In this study, a population of Vibrionaceae was isolated from shellfish of the Venice lagoon and analysed in depth to study its structure and distribution in the environment. A Multilocus Sequence Analysis (MLSA) was developed on the basis of four housekeeping genes. Both molecular and biochemical approaches were performed for species characterisation and the results were compared to assess the consistency of the two methods. In addition, strain ecology and the association between genetic information and environment were investigated through statistical models. The phylogenetic and population analyses achieved good species clustering, while biochemical identification was demonstrated to be imprecise. In addition, this study provided a fine-scale overview of the distribution of Vibrio spp. in the Venice lagoon and the results highlighted a preferential association of the species towards specific ecological variables. These findings support the use of MLSA for taxonomic studies and demonstrate the need to consider environmental information to obtain broader and veridical bacterial characterisation.