Neptunomonas concharum JCM17730 was isolated from an ark clam sample and characterized as a mesophilic bacterium. The genome of N. concharum JCM17730 contains thirteen genes related to polyhydroxyalkanoates (PHA) metabolism. Three PHA synthase encoding genes were identified, and phylogenetic analysis of enzyme sequences suggested the presence of two class I PHA synthases and one class III PHA synthase. The PHA synthases of N. concharum were heterologously expressed with acetyl-CoA acetyltransferase and acetoacetyl-CoA reductase in Escherichia coli to confirm the catalytic activity of each PHA synthase. Recombinants harboring different PHA synthase exhibit important distinctions in poly-3-hydroxybutyrate synthesis ability under various temperatures. Decreased cultivation temperature (≤30 °C) significantly improved PHB titer and content. This is the first report on characterization of PHA synthases from the marine genus Neptunomonas and would provide molecular basis for PHA production using Neptunomonas species.

从方舟蛤样品中分离出炭疽菌JCM17730，并将其表征为嗜温细菌。炭黑烟草JCM17730的基因组包含十三种与多羟基链烷酸酯（PHA）代谢相关的基因。鉴定了三个PHA合酶编码基因，并且酶序列的系统发育分析表明存在两种I类PHA合酶和一种III类PHA合酶。炭疽猪笼草的PHA合酶在大肠杆菌中与乙酰辅酶A乙酰转移酶和乙酰乙酰辅酶A还原酶异源表达以确定每种PHA合酶的催化活性。携带不同PHA合酶的重组子在不同温度下的聚3-羟基丁酸酯合成能力方面显示出重要的区别。降低的培养温度（≤30°C）可显着提高PHB滴度和含量。这是关于表征海产海产单胞菌属的PHA合成酶的第一份报告，它将为使用海产单胞菌属物种生产PHA提供分子基础。