In the present study, the abundance of Prorocentrum and the molecular phylogeny, distribution, and DST production of P. lima complex and P. caipirignum in Japan were investigated. First, the cell densities of Prorocentrum were assessed from the temperate to subtropical zones in Japan between 2014 and 2018. The cell density in the subtropical zone [19.0 ± 40.2 cells/g wet weight (ww) algae] was significantly higher than that in the temperate zone (1.4 ± 3.4 cells/g ww algae). A total of 244 clonal strains were established from the temperate and subtropical zones. Phylogenetic analyses based on the large-subunit ribosomal DNA D1/D2 revealed that the strains were separated into four species/species complex/phylotypes (P. lima complex, P. caipirignum, and new phylotypes Prorocentrum spp. types 1 and 2). The strains of P. lima complex could be separated into two clades (1 and 3). Furthermore, the strains of clades 1 and 3 could be separated into nine subclades (1a, 1c, 1d, 1e, 1f, 1g, 1h, 1i, and 1j) and three subclades (3a, 3b, and 3c), respectively. The strains of P. caipirignum were separated into two subclades (b and e). Each phylotype/subclade showed a unique distribution pattern in Japan: P. lima complex subclades 1a, 1c, and 3a and P. caipirignum subclades b and e were widespread from the temperate to subtropical zones. On the other hand, P. lima complex subclades 1e and 1i were restricted to the temperate zone, and P. lima complex subclades 1d, 1f, 1g, 1h, 1j, 3b, and 3c and Prorocentrum spp. types 1 and 2 were restricted to the subtropical zone. Furthermore, the DST production of the 243 clonal strains was assessed by LC/MS/MS analysis. The results revealed that all strains produced okadaic acid (OA) and that the OA contents of P. lima complex subclades 1d and 1f, P. caipirignum subclades b and e, and Prorocentrum sp. type 2 tended to be higher than those of the other subclades. While P. lima complex subclades 1a, 1e, 1f, and 1i produced DTX1, the other phylotype/subclades produced either no or low quantities of DTX1. A strain of P. lima complex subclade 1e showed the highest OA and DTX1 contents (55.27 and 70.73 pg/cell, respectively) in the world. These results suggest that there are potential risks for DST accumulation in benthic animals in Japan.

在本研究中，调查了日本原球藻的丰度以及利马毕赤酵母复合体和开木假单胞菌的分子系统发生，分布和DST产生。首先，对2014年至2018年日本从温带到亚热带的原中心的细胞密度进行了评估。亚热带区域的细胞密度[19.0±40.2个细胞/克湿重（ww）藻类]显着高于日本的。温带（1.4±3.4细胞/克ww藻）。从温带和亚热带地区共建立了244个克隆菌株。基于大亚基核糖体DNA D1 / D2的系统发育分析表明，该菌株被分为四个物种/物种复合体/系统型（P.利马复合体，P. caipirignum和新的系统型Prorocentrum spp。类型1和2）。利马毕赤酵母复合体的菌株可以分为两个进化枝（1和3）。此外，进化枝1和3的菌株可以分为9个子进化枝（1a，1c，1d，1e，1f，1g，1h，1i和1j）和三个子进化枝（3a，3b和3c）。caipirignum的菌株被分为两个亚属（b和e）。每个系统型/子系在日本都表现出独特的分布模式：利马毕赤酵母复杂子系1a，1c和3a，以及caipirignum子系b和e在温带至亚热带地区广泛分布。另一方面，利马体育复杂子小节1e和1i被限制在温带区域，而利马体育复杂小子1d，1f，1g，1h，1j，3b和3c和Prorocentrum spp。1型和2型仅限于亚热带地区。此外，通过LC / MS / MS分析评估了243个克隆菌株的DST产生。结果表明，所有菌株均产生冈田酸（OA），利马毕生复合体子叶1d和1f，caipirignum子叶b和e和Prorocentrum sp。中的OA含量。类型2倾向于高于其他子类别。而利马体育复杂子小节1a，1e，1f和1i产生DTX1，其他系统型/小子则不产生或产生少量DTX1。的应变利玛复杂亚枝1E显示在世界上最高的OA和DTX1内容（55.27和70.73 pg /细胞，分别地）。这些结果表明在日本底栖动物中存在DST积累的潜在风险。