The polyhydroxyalkanoate (PHA) producing capability of four bacterial strains isolated from Antarctica was reported in a previous study. This study analyzed the PHA synthase genes and the PHA-associated gene clusters from the two antarctic Pseudomonas isolates (UMAB-08 and UMAB-40) and the two antarctic Janthinobacterium isolates (UMAB-56 and UMAB-60) through whole-genome sequence analysis. The Pseudomonas isolates were found to carry PHA synthase genes which fall into two different PHA gene clusters, namely Class I and Class II, which are involved in the biosynthesis of short-chain-length-PHA (SCL-PHA) and medium-chain-length-PHA (MCL-PHA), respectively. On the other hand, the Janthinobacterium isolates carry a Class I and an uncharacterized putative PHA synthase genes. No other gene involved in PHA synthesis was detected in close proximity to the uncharacterized putative PHA synthase gene in the Janthinobacterium isolates, therefore it falls into a separate clade from the ordinary Class I, II, III and IV clades of PHA synthase (PhaC) phylogenetic tree. Multiple sequence alignment showed that the uncharacterized putative PHA synthase gene contains all the highly conserved amino acid residues and the proposed catalytic triad of PHA synthase. PHA biosynthesis and in vitro PhaC enzymatic assay results showed that this uncharacterized putative PHA synthase from Janthinobacterium sp. UMAB-60 is funtional. This report adds new knowledge to the PHA synthase database as we describe scarce information of PHA synthase genes and PHA-associated gene clusters from the antarctic bacterial isolates (extreme and geographically isolated environment) and comparing with those from non-antarctic PHA-producing bacteria.

在先前的研究中报告了从南极洲分离出的四种细菌菌株的聚羟基链烷酸酯（PHA）生产能力。本研究通过全基因组序列分析分析了两个南极假单胞菌分离株（UMAB-08和UMAB-40）和两个南极詹氏杆菌分离株（UMAB-56和UMAB-60）的PHA合酶基因和PHA相关基因簇。的假单胞菌菌株被发现，其分为两个不同的PHA的基因簇，即I类和II类，其涉及短链长度PHA（SCL-PHA）和中链-的生物合成进PHA合酶基因长度-PHA（MCL-PHA）。另一方面，詹氏菌属分离株带有I类和未鉴定的推定PHA合酶基因。在詹氏菌菌株中未检测到与未鉴定的推定PHA合酶基因非常接近的其他PHA合成基因，因此该基因与系统发育树种PHA合酶（PhaC）的普通I，II，III和IV进化枝分离。树。多序列比对显示未表征的推定PHA合酶基因包含所有高度保守的氨基酸残基和拟议的PHA合酶催化三联体。PHA生物合成和体外PhaC酶法测定结果表明，这种来自Janthinobacterium的未表征的推定PHA合酶sp。UMAB-60是功能性的。本报告向PHA合酶数据库添加了新知识，因为我们描述了来自南极细菌分离株（极端和地理上分离的环境）的PHA合酶基因和与PHA相关的基因簇的稀缺信息，并将其与非南极生产PHA的细菌进行了比较。