Characterization of saxitoxin production and release and phylogeny of sxt genes in paralytic shellfish poisoning toxin-producing Aphanizomenon gracile |
| |
| Institution: | 1. Departamento de Biología, Darwin, 2, Universidad Autónoma de Madrid, 28049 Madrid, Spain;2. Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, 0349 Oslo, Norway;1. Programa de Pós-graduação em Oceanografia Física, Química e Geológica, Instituto de Oceanografia, Universidade Federal do Rio Grande – FURG, CEP 96203-900, Cx. P. 474, Rio Grande, RS, Brazil;2. Programa de Pós-graduação em Fisiologia Animal Comparada, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande – FURG, CEP 96201-900, Cx. P 474, Rio Grande, RS, Brazil;1. Open Access Centre for Nature Research, Nature Research Centre, Akademijos Str. 2, LT-08412 Vilnius, Lithuania;2. Open Access Centre for Marine Research, Klaip?da University, H. Manto Str. 84, LT-92294 Klaip?da, Lithuania;3. Department of Marine Biotechnology, Institute of Oceanography, University of Gdańsk, al. Marsza?ka Pi?sudskiego 46, PL–81–378 Gdynia, Poland;4. Laboratory of Algology and Microbial Ecology, Nature Research Centre, Akademijos Str. 2, LT-08412 Vilnius, Lithuania;5. Atlantic Branch of P.P. Shirshov Institute of Oceanology, 1 Pr. Mira, Kaliningrad 236000, Russia;1. Biotechnology, Department of Biochemistry, University of Turku, Tykistökatu 6A 6th Floor, 20520 Turku, Finland;2. Biochemistry, Department of Biosciences, Åbo Akademi University, Tykistökatu 6A 3rd Floor, 20520 Turku, Finland;1. Centers for Disease Control and Prevention, 4770 Buford Highway, MS F44, Atlanta, GA 30341, USA;2. ORISE, Centers for Disease Control and Prevention, National Center for Environmental Health, Division of Laboratory Sciences, Atlanta, GA 30341, USA |
| |
| Abstract: | The freshwater cyanobacterium Aphanizomenon gracile is one of the most widely distributed producers of the potent neurotoxins saxitoxin (STX) and its derivatives (paralytic shellfish poisoning toxins, PSP toxins). However, the phylogeny of STX biosynthesis genes and the regulation of STX production and release remain poorly studied in the genus Aphanizomenon. In this study, two A. gracile strains from Spanish freshwaters were grown in semi-continuous cultures under three temperatures (15, 20 and 28 °C) and their STX production and release were determined by Enzyme-Linked ImmunoSorbent Assay (ELISA). STX production was stable along the temperature range, with 1.4–2.3-fold shifts in biomass-standardized STX contents, and maxima of 0.22 μg equivalent STX mg?1 dry weight 15.3 fg equiv STX cell?1 and 15.1 μg equiv STX mg?1 Chl a. The extracellular fraction was remarkably high (13.6–35.3%), not clearly affected by temperature but with nitrate-depleted medium (BG110) inducing a 2-fold increase in extracellular content. STX production and release were not directly related to growth rates. The 16S rRNA phylogenetic analyses in sixteen A. gracile strains from Spanish and German freshwaters showed that PSP-producing A. gracile grouped within a monospecific and highly supported cluster, together with PSP-producing Aphanizomenon sp. NH-5 and clearly separated from a monospecific Aphanizomenon flos-aquae cluster. The sixteen A. gracile strains formed also monospecific and highly supported clusters for PSP-biosynthesis genes (sxtG, sxtI, sxtH and sxtX) together with Aphanizomenon sp. NH-5. This study evidences an elevated extracellular proportion of STX in A. gracile with importance for risk assessment, and supports the identification of Aphanizomenon sp. NH-5 as A. gracile. |
| |
| Keywords: | Aphanizomenon Neurotoxin Paralytic shellfish poisoning Saxitoxin Sxt |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
