Iron uptake and toxin synthesis in the bloom-forming Microcystis aeruginosa under iron limitation
Iron uptake and toxin synthesis in the bloom-forming Microcystis aeruginosa under iron limitation
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DOI：
10.1111/j.1462-2920.2010.02412.x
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发表时间：
2011-04-01
影响因子：
5.1
通讯作者：
Neilan, Brett A.
中科院分区：
文献类型：
--
作者：
Alexova, Ralitza;Fujii, Manabu;Neilan, Brett A.
蓝藻水华期间产生的毒素对全球水体的公共健康构成了重大威胁，需要制定有效的水华管理策略。以前，肝毒素微囊藻毒素的合成已被提出由铁的可用性进行调节，但毒素的贡献蓝藻适应环境压力，如改变光照强度和营养限制，仍然不清楚。本研究的目的是比较铁胁迫对铜绿微囊藻毒性和无毒菌株的影响。通过定量实时PCR（qRT-PCR）获得参与铁摄取、氧化应激反应、毒素合成和这些过程的转录控制的许多基因的转录。M.铜绿假单胞菌对铁胁迫的反应是高度动态的和菌株特异性的。PCC 7806中毒素的产生以铁依赖的方式增加，并且似乎受到FurA的调节。无论是由于mcy基因簇的自然突变还是由于mcyH的插入失活，无法产生微囊藻毒素，都会影响铁应激细胞中光合机制的重塑、Fe（II）的转运和Fur家族的转录转录调节因子。毒素的存在似乎给微囊藻毒素生产蓝藻在暴露于严重的铁胁迫的早期阶段的优势，并可能保护细胞免受活性氧引起的损伤。
P>Toxin production during cyanobacterial blooms poses a significant public health threat in water bodies globally and requires the development of effective bloom management strategies. Previously, synthesis of the hepatotoxin microcystin has been proposed to be regulated by iron availability, but the contribution of the toxin to the adaptation of cyanobacteria to environmental stresses, such as changing light intensity and nutrient limitation, remains unclear. The aim of this study was to compare the iron stress response in toxic and non-toxic strains of Microcystis aeruginosa subjected to moderate and severe iron limitation. The transcription of a number of genes involved in iron uptake, oxidative stress response, toxin synthesis and transcriptional control of these processes was accessed by quantitative real-time PCR (qRT-PCR). The process of adaptation of M. aeruginosa to iron stress was found to be highly dynamic and strain-specific. Toxin production in PCC 7806 increased in an iron-dependent manner and appeared to be regulated by FurA. The inability to produce microcystin, either due to natural mutations in the mcy gene cluster or due to insertional inactivation of mcyH, affected the remodelling of the photosynthetic machinery in iron-stressed cells, the transport of Fe(II) and transcription of the Fur family of transcriptional regulators. The presence of the toxin appears to give an advantage to microcystin-producing cyanobacteria in the early stages of exposure to severe iron stress and may protect the cell from reactive oxygen species-induced damage.