Zhu Lin, Zuo Jun, Song Lirong, Gan Nanqin
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China.
J Environ Sci (China). 2016 Mar;41:195-201. doi: 10.1016/j.jes.2015.06.016. Epub 2015 Oct 23.
Cyanobacterial blooms occur increasingly often and cause ecological, economic and human health problems worldwide. Microcystins (MCs) are the dominant toxins produced by cyanobacteria and are implicated in epidemic disease and environmental problems. Extensive research has been reported on the various regulating factors, e.g., light, temperature, nutrients such as nitrogen and phosphorus, pH, iron, xenobiotics, and predators, that influence microcystin (MC) synthesis, but little is known about the effects of cyanobacteria-associated bacteria on MC synthesis. A considerable number of studies have focused on interactions between Microcystis species and their associated bacteria. In this study, we evaluated the effects of MC-degrading bacteria (MCDB) on MC synthesis gene mcyD expression and MC synthesis in axenic strain PCC7806, non-axenic strain FACHB905, and colony strain FACHB1325 of Microcystis by quantitative real-time polymerase chain reaction (RT-PCR) assay and enzyme-linked immunosorbent assay (ELISA). We demonstrate for the first time that MCDB can induce and up-regulate the MC production and transcriptional response of the mcyD gene of toxic Microcystis. On day 4 of the culturing experiment, the intracellular MC concentration and transcriptional response of mcyD of FACHB1325 were up-regulated 1.9 and 5.3-fold over that of the control, and for FACHB905 were up-regulated 1.8 and 4.2-fold over that of the control, respectively. On day 10, the transcriptional response of mcyD was up-regulated 21.3-fold in PCC7806. These results indicate that there are interactions between toxic Microcystis and MCDB, and MCDB may play a role in regulating mcyD expression in toxic Microcystis.
蓝藻水华在全球范围内愈发频繁地出现，并引发了生态、经济和人类健康问题。微囊藻毒素（MCs）是蓝藻产生的主要毒素，与流行病和环境问题相关。关于影响微囊藻毒素（MC）合成的各种调节因素，如光照、温度、氮磷等营养物质、pH值、铁、外源化合物和捕食者等，已有大量研究报道，但关于与蓝藻相关细菌对MC合成的影响却知之甚少。相当多的研究聚焦于微囊藻属物种与其相关细菌之间的相互作用。在本研究中，我们通过定量实时聚合酶链反应（RT-PCR）分析和酶联免疫吸附测定（ELISA），评估了微囊藻毒素降解细菌（MCDB）对纯培养菌株PCC7806、非纯培养菌株FACHB905和微囊藻群体菌株FACHB1325中MC合成基因mcyD表达及MC合成的影响。我们首次证明，MCDB可诱导并上调有毒微囊藻的MC产生及mcyD基因的转录反应。在培养实验的第4天，FACHB1325的细胞内MC浓度和mcyD的转录反应分别比对照上调了1.9倍和5.3倍，FACHB905则分别比对照上调了1.8倍和4.2倍。在第10天，PCC7806中mcyD的转录反应上调了21.3倍。这些结果表明，有毒微囊藻与MCDB之间存在相互作用，且MCDB可能在调节有毒微囊藻中mcyD的表达方面发挥作用。
