Effects of nitrogen and carbon on microcystin production by Microcystis aeruginosa FACHB-905
The effects of nitrogen and carbon on the growth of and microcystin production by Microcystis aeruginosa FACHB-905 were studied under laboratory conditions in continuous culture. The strains were cultivated under variable concentrations of nitrogen (3.53-35.3 mM) and carbon (0.04-1 mM) on a light-dark ratio of 12h-12h. The concentrations of microcystin in cells and in culture medium were determined by ELISA method. The results showed both the levels of microcystin in and out of the cells increased as the culture time extended, and they were significantly positive correlated with biomass. The intracellular microcystin content in different cultures has the same rules which were found in the growth of the strain. When N was fixed at 17.65 mM, the strains grown better with increasing of C ranged from 0.04 to 1 mM, while C was fixed at 0.2 mM, the strain grown better when N in 3.53 and 8.83 mM than when N in 17.65 and 35.3 mM, and the strain could barely survive when N in 35.3mM. When the ratio of N/C varied from 17.65 to 441.25 in the cultures, the lower ratio of N/C was more beneficial to the growth of the strain except the culture in which the N/C was 176 (N, 35.3 mM and C, 0.2 mM). The maximum biomass occurred in the culture which the ratio of N/C was 44.12 (C, 0.2 mM and N, 8.83 mM). The biomass depended on not only early fast growth but also supply of continuous nutrients. Cell quotas of microcystin (QMCYST) in the cultures didn’t vary much except N reached 35.3 mM in the culture which QMCYST was markedly reduced ranged from 14.53 to 3.17 fg/cell with increasing the cultivated time. The QMCYST didn’t have obvious differences between different cultures, but all of the QMCYST of 30 days was obviously lower than that of 15 days. The net microcystin production rate (μmcyst) was positively correlated with the specific cell division rate (μc), especially during early 15 days. In conclusion, C and N didn’t directly influence the QMCYST but affecting the growth of the strain. When the strain grows healthy, cell could produce microcystin at rates approximating those needed to replace losses to daughter cells during division.
Wang Jingjie Yang Jia Xian Qiming Qian Xin Sun Cheng
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment,Nanjing University, Nanjing, 210093
国际会议
武汉
英文
59
2011-04-05（万方平台首次上网日期，不代表论文的发表时间）