The extract of aquatic macrophyte Carex cinerascens induced colony formation in bloom-forming cyanobacterium Microcystis
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CYANOBACTERIAL BLOOMS AND WATER ECOLOGICAL RESTORATION
The extract of aquatic macrophyte Carex cinerascens induced colony formation in bloom-forming cyanobacterium Microcystis aeruginosa Lin Li 1,2 & Xiao-ling Jing 1,2 & Ling Wang 1,2 & Zhi-gao Zeng 1,2 & Wen-hong Chen 1,2 & Jia-hao Zhai 1,2 & Si-qin Qi 1,2 Received: 18 July 2019 / Accepted: 27 March 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Colony formation in Microcystis aeruginosa played important roles in blooms formation. To study the effects of plant allelopathy on colony formation in M. aruginosa, unicellular M. aeruginosa was cultivated under laboratory conditions treated with various extract concentration of Carex cinerascens. The growth of M. aeruginosa in the treatments with 0.05 and 0.1 mg L−1 extract of C. cinerascens was promoted but the growth in the treatments with 1.5, 3.0, and 6.0 mg L−1 C. cinerascens extract was inhibited. Obvious colony formation in M. aeruginosa was observed in all treatments while no colony formation was detected in the control. The cell number per colony at the first day was the largest and decreased along with culture time. The cell number per colony in the control ranged from 3.0 to 4.0 during the experiment. However, the values in the five treatments at the first day were 33, 80, 58, 41, and 30, respectively. A positive exponential relationship between cell number per colony of M. aeruginosa and extracellular polysaccharides (EPS) content was found as well. Compared the fold-increase in cell number per colony and the fold-increase in total biomass of M. aeruginosa at various day, it was found that colony formation induced by extract of C. cinerascens was primarily dependent on promotion of cell adhesion during the first 2 days. The cell number per colony decreased afterward was due to the increasing proportion of single cells in the culture because single cells had a great higher growth rate than M. aeruginosa colonies under culture condition. Our results suggested that plant allelopathy be one of the major factor contributing to colony formation in M. aeruginosa. Keywords Microcystis aeruginosa . Carex cinerascens . Colony formation . Allelopathy
Introduction Cyanobacterial blooms have been reported to become a major environmental issue in freshwater ecosystems around the world (Falconer, 1999; Ye et al., 2009; Zhang et al., 2011). Microcystis aeruginosa, a common bloom-forming cyanobacterial species, generally occurs as large colonies with tens of thousands of cells under natural conditions (Oliver, Responsible Editor: Vitor Manuel Oliveira Vasconcelos * Lin Li [email protected] 1
Key Laboratory of Poyang Lake Wetland and Watershed Research, Ministry of Education, Jiangxi Normal University, Nanchang 330022, People’s Republic of China
2
School of Geography and Environment, Jiangxi Normal University, Nanchang 330022, People’s Republic of China
1994; Yang et al., 2008; Xiao et al. 2018). After cultivating in the laboratory under culture conditions for multiple generations, M. aeru
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