Cirés Samuel, Wörmer Lars, Ballot Andreas, Agha Ramsy, Wiedner Claudia, Velázquez David, Casero María Cristina, Quesada Antonio
Departamento de Biología, Universidad Autónoma de Madrid, Madrid, Spain.
Appl Environ Microbiol. 2014 Feb;80(4):1359-70. doi: 10.1128/AEM.03002-13. Epub 2013 Dec 13.
Planktonic Nostocales cyanobacteria represent a challenge for microbiological research because of the wide range of cyanotoxins that they synthesize and their invasive behavior, which is presumably enhanced by global warming. To gain insight into the phylogeography of potentially toxic Nostocales from Mediterranean Europe, 31 strains of Anabaena (Anabaena crassa, A. lemmermannii, A. mendotae, and A. planctonica), Aphanizomenon (Aphanizomenon gracile, A. ovalisporum), and Cylindrospermopsis raciborskii were isolated from 14 freshwater bodies in Spain and polyphasically analyzed for their phylogeography, cyanotoxin production, and the presence of cyanotoxin biosynthesis genes. The potent cytotoxin cylindrospermopsin (CYN) was produced by all 6 Aphanizomenon ovalisporum strains at high levels (5.7 to 9.1 μg CYN mg(-1) [dry weight]) with low variation between strains (1.5 to 3.9-fold) and a marked extracellular release (19 to 41% dissolved CYN) during exponential growth. Paralytic shellfish poisoning (PSP) neurotoxins (saxitoxin, neosaxitoxin, and decarbamoylsaxitoxin) were detected in 2 Aphanizomenon gracile strains, both containing the sxtA gene. This gene was also amplified in non-PSP toxin-producing Aphanizomenon gracile and Aphanizomenon ovalisporum. Phylogenetic analyses supported the species identification and confirmed the high similarity of Spanish Anabaena and Aphanizomenon strains with other European strains. In contrast, Cylindrospermopsis raciborskii from Spain grouped together with American strains and was clearly separate from the rest of the European strains, raising questions about the current assumptions of the phylogeography and spreading routes of C. raciborskii. The present study confirms that the nostocalean genus Aphanizomenon is a major source of CYN and PSP toxins in Europe and demonstrates the presence of the sxtA gene in CYN-producing Aphanizomenon ovalisporum.
浮游丝状蓝细菌对微生物学研究来说是一项挑战，因为它们能合成多种蓝藻毒素，且具有入侵行为，而全球变暖可能会加剧这种行为。为深入了解地中海欧洲地区潜在有毒丝状蓝细菌的系统地理学，从西班牙的14个淡水水体中分离出31株鱼腥藻（粗壮鱼腥藻、莱氏鱼腥藻、门多塔鱼腥藻和浮游鱼腥藻）、束丝藻（纤细束丝藻、卵形孢束丝藻）和拉氏柱孢藻，并对其进行多相分析，以研究它们的系统地理学、蓝藻毒素产生情况以及蓝藻毒素生物合成基因的存在情况。所有6株卵形孢束丝藻都能产生强效细胞毒素柱孢藻毒素（CYN），产量较高（5.7至9.1微克CYN毫克⁻¹[干重]），菌株间差异较小（1.5至3.9倍），且在指数生长期间有明显的细胞外释放（19%至41%的溶解CYN）。在2株纤细束丝藻中检测到麻痹性贝类中毒（PSP）神经毒素（石房蛤毒素、新石房蛤毒素和脱氨甲酰基石房蛤毒素），这两株菌都含有sxtA基因。在不产生PSP毒素的纤细束丝藻和卵形孢束丝藻中也扩增出了该基因。系统发育分析支持物种鉴定，并证实西班牙的鱼腥藻和束丝藻菌株与其他欧洲菌株高度相似。相比之下，来自西班牙的拉氏柱孢藻与美国菌株聚在一起，明显与其他欧洲菌株分开，这引发了关于拉氏柱孢藻当前系统地理学假设和传播途径的疑问。本研究证实束丝藻属是欧洲CYN和PSP毒素的主要来源，并证明在产生CYN的卵形孢束丝藻中存在sxtA基因。
