Associations of Environmental Conditions and Vibrio parahaemolyticus Genetic Markers in Washington State Pacific Oysters
Associations of Environmental Conditions and Vibrio parahaemolyticus Genetic Markers in Washington State Pacific Oysters
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DOI：
10.3389/fmicb.2019.02797
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发表时间：
2019-12-04
影响因子：
5.2
通讯作者：
Curriero, Frank C.
中科院分区：
文献类型：
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作者：
Flynn, Aspen;Davis, Benjamin J. K.;Curriero, Frank C.
副溶血性弧菌是一种天然存在于河口水域的细菌，是海产品传播疾病的主要原因。这种细菌一直在太平洋西北水域被发现，华盛顿州弧菌病发病率的上升引起了太平洋牡蛎（长牡蛎）种植者、风险管理人员和消费者的关注。为了更好地了解该地区副溶血性弧菌采收前的变异情况，我们将大量华盛顿州太平洋牡蛎样品中副溶血性弧菌总菌株和潜在致病性菌株的丰度与采样时的环境条件进行了比较。2014年至2018年，华盛顿卫生部在6月至9月期间定期在21个地点对牡蛎进行采样，共采集了946多个样本。利用最可能数- pcr分析，在牡蛎组织中发现了携带3个遗传标记tlh、trh和tdh的副溶血性弧菌。Tobit回归和看似无关的估计被用于正式评估环境措施和遗传标记之间的关系。所有遗传标记均与温度呈正相关，与其他遗传标记的丰度无关。地表水温度表现出非线性关系，在最温暖的水域中没有观察到任何遗传标记之间的关联。地表和海岸水温模型之间也存在明显差异。没有发现盐度与任何遗传变量有实质性的联系。副溶血性弧菌总丰度（致病性比tdh:tlh）下，tdh+菌株的相对丰度与水温呈负相关，随着副溶血性弧菌总丰度的增加呈指数型下降。携带trh基因的菌株与携带tdh基因的菌株呈显著正相关，但与tdh:tlh致病性比呈负相关。这些结果表明，在牡蛎组织基质中，副溶血性弧菌菌株之间存在着竞争、生长和生存的生态关系。这项工作还提高了对华盛顿州太平洋牡蛎中副溶血性弧菌的环境关联的整体理解，为该地区未来的风险缓解工作奠定了基础。
Vibrio parahaemolyticus is a naturally occurring bacterium in estuarine waters and is a major cause of seafood-borne illness. The bacterium has been consistently identified in Pacific Northwest waters and elevated illness rates of vibriosis in Washington State have raised concerns among growers, risk managers, and consumers of Pacific oysters (Crassostrea gigas). In order to better understand pre-harvest variation of V. parahaemolyticus in the region, abundance of total and potentially pathogenic strains of the bacterium in a large number of Washington State Pacific oyster samples were compared with environmental conditions at the time of sampling. The Washington Department of Health regularly sampled oysters between June and September at over 21 locations from 2014 to 2018, resulting in over 946 samples. V. parahaemolyticus strains carrying three genetic markers, tlh, trh, and tdh, were enumerated in oyster tissue using a most probable number-PCR analysis. Tobit regressions and seemingly unrelated estimations were used to formally assess relationships between environmental measures and genetic markers. All genetic markers were found to be positively associated with temperature, independent of the abundance of other genetic markers. Surface water temperature displayed a non-linear relationship, with no association observed between any genetic marker in the warmest waters. There were also stark differences between surface and shore water temperature models. Salinity was not found to be substantially associated with any of the genetic variables. The relative abundance of tdh+ strains given total V. parahaemolyticus abundance (pathogenic ratio tdh:tlh) was negatively associated with water temperature in colder waters and decreased exponentially as total V. parahaemolyticus abundance increased. Strains carrying the trh gene had a pronounced positive association with strains carrying the tdh gene but was also negatively associated with the tdh:tlh pathogenic ratio. These results suggest that there are ecological relationships of competition, growth, and survival for V. parahaemolyticus strains in the oyster tissue matrix. This work also improves the overall understanding of environmental associations with V. parahaemolyticus in Washington State Pacific oysters, laying the groundwork for future risk mitigation efforts in the region.