Dataset Information

Population structure of Alexandrium (Dinophyceae) cyst formation-promoting bacteria in Hiroshima Bay, Japan.

ABSTRACT: A total of 31 bacterial isolates that have potential Alexandrium cyst formation-promoting activity (Alex-CFPB) were isolated from Hiroshima Bay (Japan), which is characterized by seasonal blooms of the toxic dinoflagellate Alexandrium tamarense. The population structure of Alex-CFPB was analyzed by means of restriction fragment length polymorphism analysis of the 16S rRNA genes (16S rDNA). Fourteen ribotypes, A to N, were observed among the 31 isolates of Alex-CFPB by using four restriction enzymes, MboI, HhaI, RsaI and BstUI. Among them, seven isolates, which were obtained from the seawater samples taken during the peak and termination periods of the A. tamarense bloom in 1998, belonged to ribotype A. This result suggests that bacterial strains of ribotype A may be dominant in the Alex-CFPB assemblages during these periods. The partial 16S rDNA-based phylogenetic tree of 10 ribotypes studied showed that nine of them fell into the Rhodobacter group of the alpha subclass of the Proteobacteria: Eight of nine ribotypes of the Rhodobacter group fell into the lineage of the Roseobacter subgroup, and one fell into the Rhodobacter subgroup. The non-Rhodobacter group type fell into the Marinobacterium-Neptunomonas-Pseudomonas group of the gamma-Proteobacteria: Isolates of Alex-CFPB ribotypes A and C do not have clear growth-promoting activities but have strong cyst formation-promoting activities (CFPAs) under our laboratory conditions. These results show that the Alex-CFPB assemblage may consist of various bacteria that belong mainly to the Roseobacter group and have strong CFPAs. These results suggest that not only the Alexandrium cyst formation-inhibiting bacteria (Alex-CFIB) reported previously but also Alex-CFPB, especially bacteria of ribotype A, may play significant roles in the process of encystment and bloom dynamics of Alexandrium in the natural environment.

SUBMITTER: Adachi M

PROVIDER: S-EPMC262264 | biostudies-literature | 2003 Nov

REPOSITORIES: biostudies-literature

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Population structure of Alexandrium (Dinophyceae) cyst formation-promoting bacteria in Hiroshima Bay, Japan.

Adachi Masao M Kanno Tsukasa T Okamoto Ryo R Itakura Shigeru S Yamaguchi Mineo M Nishijima Toshitaka T

Applied and environmental microbiology 20031101 11

A total of 31 bacterial isolates that have potential Alexandrium cyst formation-promoting activity (Alex-CFPB) were isolated from Hiroshima Bay (Japan), which is characterized by seasonal blooms of the toxic dinoflagellate Alexandrium tamarense. The population structure of Alex-CFPB was analyzed by means of restriction fragment length polymorphism analysis of the 16S rRNA genes (16S rDNA). Fourteen ribotypes, A to N, were observed among the 31 isolates of Alex-CFPB by using four restriction enzy ...[more]

PMID: 14602614

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Project description:Paralytic shellfish poisoning (PSP) poses a serious health threat in Alaska and prevents effective utilization of shellfish resources by subsistence and recreational harvesters. Substantial economic losses also affect shellfish growers during PSP events. The toxins responsible for PSP are produced by dinoflagellates in the genus Alexandrium. Despite the persistent threat posed by PSP and the long history of shellfish toxicity research, there is still confusion concerning the Alexandrium species that cause PSP in Alaska. The primary objective of this study was to identify the toxic Alexandrium species present in Alaska and to develop polymerase chain reaction (PCR) assays for use in screening phytoplankton and sediment samples. Before developing the PCR assays for this study, we evaluated published assays and many were not adequate because of primer dimer formation or because of cross-reactivity. Rather than continue to grapple with the uncertainty and inadequacy of published assays, we developed new assays for the Alexandrium species most likely to be present in Alaska. Only Alexandrium fundyense Group I and A. ostenfeldii were identified from four sampling regions from southeast Alaska to Kodiak Island, indicating that these two species are widely distributed. PCR assays for these two species were converted to quantitative (q)PCR format for use in monitoring programs. During the course of this study, we realized that a systematic evaluation of all published (~150) Alexandrium species-specific assays would be of benefit. Toward this objective, we collated published Alexandrium PCR, qPCR, and in situ hybridization assay primers and probes that targeted the small-subunit (SSU), internal transcribed spacer (ITS/5.8S), or D1-D3 large-subunit (LSU) (SSU/ITS/LSU) ribosomal DNA genes. Each individual primer or probe was screened against the GenBank database and Alexandrium gene sequence alignments constructed as part of this study. These data were used to identify a suite of species-specific Alexandrium assays that can be recommended for evaluation by the global harmful algal bloom community.

Dataset Information

Population structure of Alexandrium (Dinophyceae) cyst formation-promoting bacteria in Hiroshima Bay, Japan.

Publications

Population structure of Alexandrium (Dinophyceae) cyst formation-promoting bacteria in Hiroshima Bay, Japan.

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