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Harmful algal blooms: mechanisms, monitoring, and prevention in a rapidly changing world
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Study on algicidal functional microbes against Prorocentrum donghaiense blooms
P-B1-02-S
Fuxing Zhang* , School of Life Sciences, Xiamen University
Qian Ye, School of Life Sciences, Xiamen University
Danyang Zhang, School of Life Sciences, Xiamen University
Xueping Shao, School of Life Sciences, Xiamen University
Yongxiang Fan, School of Life Sciences, Xiamen University
Jiali Gui, School of Life Sciences, Xiamen University
Sisi Zheng, School of Life Sciences, Xiamen University
Yun Tian, School of Life Sciences, Xiamen University
Tianling Zheng, School of Life Sciences, Xiamen University
Hong Xu, School of Life Sciences, Xiamen University
Presenter Email: zhangfx_xmu@163.com |
| Prorocentrum donghaiense has caused most frequent large-scale blooms at the Yangtze River Estuary and the adjacent East China Sea in recent years, bringing tremendous economic losses and local environments serious impacts. Therefore, it is urgent to search for potent and ecofriendly methods to control Prorocentrum donghaiense blooms. Compared with physical and chemical methods, biological-control is an effective and specific method to control red tide. Decades of studies have reported that algicidal bacteria exert algicidal activity by direct or indirect mode. To find the potential algicidal bacteria and apply them to eliminate the harmful blooms of Prorocentrum donghaiense, in this study, strain SCM-1T, which exhibited high algicidal activity against P. donghaiense, was isolated from coastal surface sediment and identified as the bacterium Sulfitobacter, the algicidal efficiency achieved to 95% after 72 h. To investigate the algicidal mechanism of strain SCM-1T, the different fractions of the SCM-1T cultures, including bacterial cells and cell-free supernatant, were added to the algal cultures at a concentration of 5% (v/v) to assess their algicidal activities. The result showed that the strain SCM-1T was indirectly attacked by secreting algicidal compounds to the supernatant, and the algicidal activity of the SCM-1T supernatant was stable under different temperatures, light intensities and wide pH range (pH 3-12). In addition to showing algicidal activity against P. donghaiense, the supernatant of SCM-1T showed strong algicidal activity against Alexandrium minutum and Scrippsiella trochoidea. To explore the algicidal mechanism of the action of the SCM-1T supernatant, the morphological alteration, chlorophyll a content, photosynthetic activity, and reactive oxygen species (ROS) content of P. donghaiense were investigated. The scanning and transmission electron microscopy showed that the SCM-1T supernatant destroyed the cell membrane structure and the inclusion of algal cell leaked out. The decrease of photosynthetic pigments, photosynthetic efficiency (Fv/Fm) and electron transport rate (rETR) demonstrated the SCM-1T supernatant could inhibit the activity of the photosystem of P. donghaiense. The dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay showed that the ROS levels in algae treated with the SCM-1T supernatant were 1.33-fold higher than those in control after 2 h treatment. These results indicated that the SCM-1T supernatant induced the production of excessive ROS, damaged cell membrane and destroyed photosynthesis system which caused algal cell death. This research reports the potential of strain SCM-1T to control P. donghaiense blooms. |
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