The eastern oyster (Crassostrea virginica) is a keystone species in estuarine environments but faces threats to shell formation associated with warming temperatures and acidification. Extrapallial fluid (EF), which is responsible for shell formation, harbors diverse and abundant microbial communities. Commensal microbial communities are vital to host health and fitness, yet long-term studies investigating temporal responses of the EF microbiome and its function in oyster fitness are lacking. In this study, bacterial communities of oyster EF and the water column were characterized monthly from October 2010 to September 2011. We investigated the selection, composition, and dynamics of resident and transient community members, evaluated the impact of temperature on EF microbial communities, and examined the functional role of the EF microbiome. Oyster EF communities were significantly different from the water column and were enriched for several taxa, including the Deltaproteobacteria, Epsilonproteobacteria, and Gammaproteobacteria. Overall, 94 resident members were identified in oyster EF. These members were persistent and abundant, comprising on average 33% of EF communities. Resident EF communities formed high-temperature and low-temperature groups and were more abundant overall at colder temperatures. Oyster EF resident communities were predicted to be enriched for dissimilatory nitrate reduction, nitrogen fixation, nitrification, and sulfite reductase genes. Sulfate and nitrate reduction may have a synergistic effect on calcium carbonate precipitation and indirectly aid in shell formation. Therefore, the potential role of the oyster EF microbiome in shell formation warrants further investigation as oysters and other shellfish face the future impacts of ocean warming and acidification.

中文翻译：

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牡蛎钙化液含有持久和动态的本地细菌种群，可能有助于壳的形成

东部牡蛎（Crassostrea virginica）是河口环境中的关键物种，但面临与温度升高和酸化相关的壳形成威胁。外层液 (EF) 负责外壳形成，拥有多样化和丰富的微生物群落。共生微生物群落对宿主的健康和健身至关重要，但缺乏调查 EF 微生物组的时间响应及其在牡蛎健身中的功能的长期研究。在这项研究中，从 2010 年 10 月到 2011 年 9 月，每月对牡蛎 EF 和水柱的细菌群落进行表征。我们调查了常驻和临时群落成员的选择、组成和动态，评估了温度对 EF 微生物群落的影响，并检查了 EF 微生物组的功能作用。牡蛎 EF 群落与水柱显着不同，并且富含多种分类群，包括 Deltaproteobacteria、Epsilonproteobacteria 和 Gammaproteobacteria。总体而言，在牡蛎 EF 中确定了 94 名常驻成员。这些成员持久而丰富，平均占 EF 社区的 33%。居民 EF 社区形成了高温和低温组，并且在较冷的温度下整体更为丰富。预计牡蛎 EF 居民社区富含异化硝酸盐还原、固氮、硝化和亚硫酸盐还原酶基因。硫酸盐和硝酸盐的还原可能对碳酸钙沉淀产生协同作用，并间接有助于壳的形成。所以，