Effects of elevated CO2 on dynamics of microcystin-producing and non-microcystin-producing strains during Microcystis blooms

• Published in: Journal of environmental sciences (China) 2015, Vol.27 (1), p.251-258
• Main Authors: Yu, Li, Kong, Fanxiang, Shi, Xiaoli, Yang, Zhen, Zhang, Min, Yu, Yang
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Carbon Dioxide - metabolism; China; CO2浓度升高; Dose-Response Relationship, Drug; Eutrophication; Genotype; Harmful cyanobacterial blooms; Inorganic carbon; Lakes - microbiology; Microcystin; Microcystins - genetics; Microcystins - metabolism; Microcystis; Microcystis - genetics; Microcystis - growth & development; Microcystis - metabolism; Real-time PCR; Real-Time Polymerase Chain Reaction; RNA, Ribosomal, 16S - genetics; RNA, Ribosomal, 16S - metabolism; 二氧化碳浓度; 产生菌; 微囊藻毒素; 生产; 繁殖; 蓝藻水华; 高浓度CO2
• ISSN: 1001-0742; 1878-7320
• DOI: 10.1016/j.jes.2014.05.047

In an attempt to elucidate the effects of different CO2concentrations（270, 380, and 750 μL/L） on the competition of microcystin-producing（MC-producing） and non-MC-producing Microcystis strains during dense cyanobacteria blooms, an in situ simulation experiment was conducted in the Meiliang Bay of Lake Taihu in the summer of 2012. The abundance of total Microcystis and MC-producing Microcystis genotypes was quantified based on the 16 S r DNA and mcy D gene using real-time PCR. The results showed that atmospheric CO2 elevation would significantly decrease the p H value and increase the dissolved inorganic carbon（DIC） concentration.Changes in CO2 concentration did not show significant influence on the abundance of total Microcystis population. However, CO2 concentrations may be an important factor in determining the subpopulation structure of Microcystis. The enhancement of CO2 concentrations could largely increase the competitive ability of non-MC-producing over MC-producing Microcystis, resulting in a higher proportion of non-MC-producing subpopulation in treatments using high CO2 concentrations. Concurrently, MC concentration in water declined when CO2 concentrations were elevated. Therefore, we concluded that the increase of CO2 concentrations might decrease potential health risks of MC for human and animals in the future.