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首页> 外文期刊>Harmful Algae >Characterization of saxitoxin production and release and phylogeny of sxt genes in paralytic shellfish poisoning toxin-producing Aphanizomenon gracile
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Characterization of saxitoxin production and release and phylogeny of sxt genes in paralytic shellfish poisoning toxin-producing Aphanizomenon gracile

机译：麻痹性贝类毒物毒素Aphanizomenon gracile中毒毒素的产生，释放和sxt基因的系统发育

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摘要

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 ℃) 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 (BG11_0) 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.
机译：淡水蓝藻Aphanizomenon gracile是强效神经毒素saxitoxin（STX）及其衍生物（麻痹性贝类毒素，PSP毒素）的最广泛生产者之一。但是，在Aphanizomenon属中，STX生物合成基因的系统发育以及STX产生和释放的调控仍然很少。在这项研究中，来自西班牙淡水的两株嗜草曲霉菌株在三种温度（15、20和28℃）下半连续培养，并通过酶联免疫吸附测定（ELISA）测定了它们的STX产生和释放。在温度范围内，STX的产量稳定，生物量标准化的STX含量变化1.4-2.3倍，最大当量STX mg〜（-1）干重为0.22μg（当量）15.3 fg当量STX cell〜（-1）和15.1。微克当量STX mg〜（-1）Chl a。细胞外部分非常高（13.6-35.3％），不受温度的影响明显，但硝酸盐缺乏的培养基（BG11_0）引起细胞外含量增加2倍。 STX的生产和释放与增长率没有直接关系。在16种来自西班牙和德国淡水的A. gracile菌株中的16S rRNA系统发育分析表明，生产PSP的A. gracile与生产PSP的Aphanizomenon sp。一起归类在一个单特异性和高度支持的簇中。 NH-5，清楚地与单特异的Aphanizomenon flos-aquae簇分离。十六种曲霉菌株还与Aphanizomenon sp一起形成了PSP生物合成基因（sxtG，sxtI，sxtH和sxtX）的单特异性和高度支持的簇。 NH-5。这项研究表明拟南芥中STX的胞外比例升高，这对风险评估很重要，并支持鉴定Aphanizomenon sp。 NH-5为A. gracile。

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  • 来源
    《Harmful Algae》 |2014年第7期|28-37|共10页
  • 作者

    Maria Cristina Casero; Andreas Ballot; Ramsy Agha; Antonio Quesada; Samuel Cires;

  • 作者单位

    Departamento de Biologia, Darwin, 2, Universidad Autonoma de Madrid, 28049 Madrid, Spain;

    Norwegian Institute for Water Research (NIVA), Gaustadalleen 21, 0349 Oslo, Norway;

    Departamento de Biologia, Darwin, 2, Universidad Autonoma de Madrid, 28049 Madrid, Spain;

    Departamento de Biologia, Darwin, 2, Universidad Autonoma de Madrid, 28049 Madrid, Spain;

    Departamento de Biologia, Darwin, 2, Universidad Autonoma de Madrid, 28049 Madrid, Spain,School of Marine and Tropical Biology,James Cook University, Townsville, QLD 4811, Australia;

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  • 正文语种 eng
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  • 关键词

    Aphanizomenon; Neurotoxin; Paralytic shellfish poisoning; Saxitoxin; Sxt;

    机译：Aphanizomenon;神经毒素麻痹性贝类中毒;毒素t;

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