| 不同铁浓度对单细胞和群体铜绿微囊藻生长的影响 |
| 摘要点击 3238 全文点击 1930 投稿时间：2008-01-22 修订日期：2008-03-24 |
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| 中文关键词 铜绿微囊藻 水华 群体 铁载体 铁限制 |
| 英文关键词 Microcysits aeruginosa water blooms colony siderophore iron-limited |
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| 中文摘要 |
| 分别在限铁和富铁的条件下，比较研究了Microcystis aeruginosa PCC7806(单细胞株)和M.aeruginosa XW01(群体株)2株铜绿微囊藻的生长、光合作用效率、铁载体分泌及其细胞对铁元素的积累.2株藻的ITS 序列相似性为95%，铁吸收调节蛋白基因fur的序列相似性为98%，二者具有很高的遗传相似性.研究表明，在限铁条件下单细胞株微囊藻生长受到抑制，在第 6 d藻体黄化死亡，但群体株在限铁条件下能维持一定的生长; 限铁条件下最大光能转化效率(Fv/Fm)群体株高于单细胞株，二者分别为0.182±0.014和0.160±0.017.群体株比单细胞株有更高的光合作用能力; 2株藻均可产生铁载体菌株，其铁载体类型为氧肟酸盐型.在限铁条件下，群体株比单细胞株产生更多的铁载体.通过测定藻体铁的含量，发现缺铁条件下藻体积累的铁含量不足富铁条件下的1/3，但不同铁浓度培养的2株藻之间铁含量差异不大.研究结果显示，群体株比单细胞株有更强的适应低铁环境的能力，其机制并非是由于二者对铁吸收和积累的差异导致，可能是由于单细胞株的其他生理代谢过程对细胞内低铁状态更为敏感. |
| 英文摘要 |
| We investigated the growth，photosynthetic efficiency，siderophore production and iron accumulation of two strains of M.aeruginosa，a unicellular strain M.aeruginosa PCC7806 and a colonial strain M.aeruginosa XW01，under iron-limited and iron-replete conditions.The identities of ITS and fur gene sequences of two strains were 95% and 98% respectively.That implied the two strains should be close relatives.Results showed the growths of two strains were severely inhibited under an iron-limited condition.The unicellular strain died in 6 days，whereas the colonial strain could maintain a weak growth in 10 days under the iron-limited condition.PSII maximum light energy transformation (Fv/Fm) of the colonial strain and the unicellular strain were 0.182±0.014 and 0.160±0.017，respectively.The colonial strain displayed a higher photosynthetic oxygen evolution than the unicellular strain.Two strains could produce siderophores，which were hydroxamate type.The colonial strain produced more siderophores than unicellular strain under the iron-limited condition.Iron contents of two strains were less than 1/3 cultured in the iron-limited condition than in iron-replete condition，but no obvious difference appeared between the two strains.Our result demonstrated that the colonial strain have a stronger endurance than unicellular strain under the iron-limited condition.As two strains had almost same abilities of iron accumulation，the other physiological mechanisms in the unicellular strain should be more sensitive to lower iron level. |
