Microcystin content of Microcystis aeruginosa is modulated by nitrogen uptake rate relative to specific growth rate or carbon fixation rate
Microcystin content of Microcystis aeruginosa is modulated by nitrogen uptake rate relative to specific growth rate or carbon fixation rate
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DOI：
10.1002/tox.20106
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发表时间：
2005-06-01
影响因子：
4.5
通讯作者：
van de Venter, M
中科院分区：
文献类型：
--
作者：
Downing, TG;Meyer, C;van de Venter, M
微囊藻毒素产生的调控已经在分批和连续培养中被广泛研究。正相关与中氮，中磷，光照强度，无机碳的有效性，和生长速度已被报道。据报道，微囊藻毒素含量与。中磷任何变量和微囊藻毒素生产之间的定量关系的唯一报告是增长率。因此，铜绿微囊藻PCC 7806在连续培养条件下在鼓泡提升式反应器中以0.01 h（-1）的生长速率在改良的BG 11中培养（恒定的磷酸盐浓度为0.195 mM，硝酸盐浓度为0.125 - 18 mM），并在稳定状态下取样，用于分析细胞数、微囊藻毒素含量、细胞N和P、残留培养基营养物浓度，和固碳率。细胞内微囊藻毒素含量与硝酸盐吸收量和细胞内氮含量呈显著正相关，与固碳率、磷酸盐吸收量和细胞内磷含量呈显著负相关。因此，硝酸盐吸收的比例，磷酸盐吸收，细胞N细胞P，和硝酸盐吸收碳固定细胞微囊藻毒素呈正相关。微囊藻毒素配额增加了10倍，从最低到最高的稳态值。因此，细胞内微囊藻毒素含量在很大程度上是由生长速率以外的变量控制的，如先前所报道的，其中氮是最重要的调节剂。BG 11在相同条件下的分批培养产生增加的微囊藻毒素时，氮的吸收超过相对生长速率，确认氮的吸收在特定的生长速率的微囊藻毒素含量的调制的重要性。(c)2005 Wiley Periodicals，Inc.
Modulation of microcystin production has been extensively studied in both batch and continuous cultures. Positive correlations with medium nitrogen, medium phosphorous, light intensity, inorganic carbon availability, and growth rate have been reported. Negative correlations have been reported between microcystin content and. medium, phosphorous. The only reported quantitative relationship between any variable and microcystin production was that of growth rate. Microcystis aeruginosa PCC7806 was therefore cultured under continuous culture conditions in a bubble-lift reactor at a growth rate of 0.01 h(-1) in modified BG11 (constant phosphate concentration of 0.195 mM and varying nitrate from 0.125 to 18 mM) and sampled at steady states for analysis of cell number, microcystin content, cellular N and P, residual medium nutrient concentration, and carbon fixation rate. Cellular microcystin quotas showed significant positive correlation with both nitrate uptake and cellular nitrogen content and were negatively correlated with carbon fixation rate, phosphate uptake, and cellular phosphorous. Thus, the ratio of nitrate uptake to phosphate uptake, cellular N to cellular P, and nitrate uptake to carbon fixation were positively correlated to cellular microcystin. Microcystin quotas increased 10-fold from the lowest to the highest steady-state values. Cellular microcystin content therefore is controlled to a significant extent by variables other than growth rate, as was previously reported, with nitrogen the most significant modulator. Batch culture in BG11 under identical conditions yielded increased microcystin when nitrogen uptake exceeded relative growth rate, confirming the importance of nitrogen uptake in the modulation of microcystin content for a specific growth rate. (c) 2005 Wiley Periodicals, Inc.