Dynamics and Microevolution of Vibrio parahaemolyticus Populations in Shellfish Farms

Abstract

Vibrio parahaemolyticus is becoming the leading cause of acute bacterial gastroenteritis, but its population dynamics in aquafarms have received limited attention. To address this research gap, we selected three shellfish farms to examine the impacts of ocean currents and the transport of live aquatic animals on the transmission and microevolution of V. parahaemolyticus by using multilocus sequence typing (MLST) and whole-genome sequencing. MLST and genomic analysis revealed that the community structure of V. parahaemolyticus in Dalian and Donggang was relatively stable in the presence of ocean currents; however, horizontal gene transfer of mobile genetic elements (MGEs) between Dalian and Donggang was very common. Further analysis indicated that the transport of live aquatic animals from Dalian to Xiamen not only introduced new V. parahaemolyticus populations but also allowed the exchange of genetic material between the two sites. More interestingly, Dalian-originated strain ST722 was introduced to Xiamen farms, resulting in one MLST allele change and the acquisition of two genomic islands from indigenous isolates in Xiamen within 8 months; such alterations are thought to promote the adaptation of V. parahaemolyticus. These results provide direct observations of how ocean currents and the transport of live aquatic animals contribute to the dissemination and genetic mixture of V. parahaemolyticus, which provides insights into the dynamics and microevolution of V. parahaemolyticus in aquacultural environments. IMPORTANCE Globally, V. parahaemolyticus-related gastroenteritis outbreaks caused by seafood consumption represent an increasing threat to human health. Despite advances in our understanding of the global epidemiology of pandemic V. parahaemolyticus, fundamental questions about the key driving forces for the spread of V. parahaemolyticus at regional and national scales remain unanswered. This study revealed that the transregional transport of aquatic animals and the movement of ocean currents both contributed to the mixing of V. parahaemolyticus populations. More importantly, this study demonstrated how genetic mixture occurred between introduced and endemic V. parahaemolyticus populations via the transport of aquatic animals, which accelerated bacterial adaptation by transferring ecologically important functions. These results suggest that human activities entail a risk of the emergence of new virulent populations for both aquatic animals and humans by horizontal gene transfer and provide important insights into the microevolution and population mixing of V. parahaemolyticus.

Distinct dynamics of Vibrio parahaemolyticus populations in two farming models

“…We described the results by grouping STs to observe genomic variations. ST114 isolates from five locations were geographically distinct (Figure 3b), of which Yingkou isolates were clustered with Dalian isolates identified in our previous study (Fu et al, 2021b). Relative to other Yingkou isolates, VP14-2020 had only one SNP.…”

“…Intensive aquacultural activities in traditional farms might also provide a suitable niche for HGT between Vibrio spp. and other bacteria (Fu et al, 2021b). However, there is no long‐term surveillance on V .…”

“…Thus, distinct dynamics of the population structure of V. parahaemolyticus may have resulted from geographical variability rather than agricultural methods. However, based on our pathogen surveillance on the shrimp farms along the coastal line in this region, many STs were shared amongst different locations and were genetically related within the same STs (Fu et al, 2021b). For instance, ST864, ST1073, ST1166, ST12, ST114 and ST1986 were commonly found in Tangshan, Cangzhou, Dalian and Yingkou located within the Bohai Sea (Figure S1).…”

Distinct respiratory microbiota associates with lung cancer clinicopathological characteristics

“…Then, the differences in taxonomic diversity of respiratory microbiota in lung cancer and benign pulmonary lesion tissues were analyzed. ANOSIM (analysis of similarities) is mainly used to analyze inter-group similarity of high-dimensional data and provide a basis for inter-group difference evaluation ( 21 ). ANOSIM suggested that significant differences existed in LUSC, LUAD, and BPD groups ( Table S3 ).…”

Sources and contamination routes of seafood with human pathogenic Vibrio spp.: A Farm‐to‐Fork approach

“…Notably, four strains of V. parahaemolyticus displayed resistance to amoxicillin, cephalothin, erythromycin, and streptomycin, whereas one remaining strain of V. vulnificus exhibited resistance to oxolinic acid, flumequine, and sulfadiazine (Scarano et al., 2014). It has also been demonstrated that the transport of shellfish from one farm to another had been proven to favor the transmission and microevolution of V. parahaemolyticus populations due to genomic exchanges (Fu et al., 2021a). However, the stocking density is a critical point in industry, in which balance between productivity and operational costs is essential to ensure both animals health and welfare, as well as the economic well‐being of the company.…”