摘要
Cyanobacterial blooms are a global problem, with their occurrence tightly tied to nutrient loading. We cultured Microcystis aeruginosa FACHB-905 in growth medium with either inorganic(orthophosphate) or organic(β-glycerophosphate or polyphosphate) phosphorus and at different N:P ratios with 50:1, 30:1, 16:1, 4:1 and 1:4, serving as the phosphorus source. Fluorescence parameters were measured to determine the response of cellular responses to nutrient stress. Scanning electron microscopy(SEM) and estimates of antioxidant activity were employed to examine potential mechanisms of physical change. The results demonstrate that inorganic phosphorus was more bioavailable to M. aeruginosa relative to organic phosphorus in culture. The highest cell concentration(2.21×10~6 cells/mL), chlorophyll-a(0.39 pg/cell) and phycocyanin(1.57 pg/cell) quotas and high levels of chlorophyll fluorescence parameters( rETR, E_k, α, φ_(PSⅡ) and F_v/F_m) were obtained when phosphorus was supplied as K_2 HPO_4 at a N:P ratio of 16–30. Organic sources of phosphorus(β-glycerophosphate and polyphosphate) were bioavailable to M. aeruginosa. In addition, too concentrated orthophosphate(N:P=1:4) resulted in the oxidative stress and lipid peroxidation of cell membrane(identified by the antioxidant system activity), and the photosynthetic activity declined consequently. This study has demonstrated the effects of different phosphorus chemistries and N:P ratios on the cyanobacterial growth, photosynthetic activity and cell physiology, which could be an effective tool for predicting cyanobacterial dominance or N-deficiency in natural lakes(due to the superior ability of cyanobacteria for dissolved N and fix atmospheric N in some cases).
Cyanobacterial blooms are a global problem, with their occurrence tightly tied to nutrient loading. We cultured Microcystis aeruginosa FACHB-905 in growth medium with either inorganic（orthophosphate） or organic（β-glycerophosphate or polyphosphate） phosphorus and at different N：P ratios with 50：1, 30：1, 16：1, 4：1 and 1：4, serving as the phosphorus source. Fluorescence parameters were measured to determine the response of cellular responses to nutrient stress. Scanning electron microscopy（SEM） and estimates of antioxidant activity were employed to examine potential mechanisms of physical change. The results demonstrate that inorganic phosphorus was more bioavailable to M. aeruginosa relative to organic phosphorus in culture. The highest cell concentration（2.21×10~6 cells/mL）, chlorophyll-a（0.39 pg/cell） and phycocyanin（1.57 pg/cell） quotas and high levels of chlorophyll fluorescence parameters（ rETR, E_k, α, φ_（PSⅡ） and F_v/F_m） were obtained when phosphorus was supplied as K_2 HPO_4 at a N：P ratio of 16–30. Organic sources of phosphorus（β-glycerophosphate and polyphosphate） were bioavailable to M. aeruginosa. In addition, too concentrated orthophosphate（N：P=1：4） resulted in the oxidative stress and lipid peroxidation of cell membrane（identified by the antioxidant system activity）, and the photosynthetic activity declined consequently. This study has demonstrated the effects of different phosphorus chemistries and N：P ratios on the cyanobacterial growth, photosynthetic activity and cell physiology, which could be an effective tool for predicting cyanobacterial dominance or N-deficiency in natural lakes（due to the superior ability of cyanobacteria for dissolved N and fix atmospheric N in some cases）.
作者
PENG Guotao
Steven W.WILHELM
LIN Sijie
WANG Xlangrong
彭国涛;Steven W.WILHELM;林思劼;王祥荣(College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University;Department of Environmental Science and Engineering, Fudan University;Department of Microbiology, University of Tennessee)
基金
Supported by the National Key R&D Program of China(No.2016YFC0502700)
the Major Program of National Social Science Foundation of China(No.14ZDB140)
the National Science Foundation(USA)(Nos.IOS1451528,DEB1240870)
