铜绿微囊藻高温胁迫后的生长补偿效应

为探究藻类受高温胁迫后的恢复生长情况,以铜绿微囊藻(Microcystis aeruginosa)为材料,设置了40 ℃高温组及25 ℃对照组,分别处理3、6和12 d后转入25 ℃进行恢复培养30 d,测定生长过程中的细胞密度以及Chla(叶绿素a)、CAR(类胡萝卜素)、Pro(可溶性蛋白)、Sug(可溶性糖)和丙二醛的含量. 结果表明:40 ℃高温下铜绿微囊藻的生长受到显著抑制,胁迫至第12天时,细胞密度、ρ(Chla)和ρ(CAR)分别比对照组降低了81.08%、97.89%和90.31%. 解除胁迫后,40 ℃处理3 d组呈现一定的超补偿,细胞密度、ρ(Chla)和ρ(CAR)在恢复培养30 d的平均补偿指数分别为1.63、0.90和2.12；40 ℃处理6和12 d组呈现低补偿,恢复培养至第30天时,ρ(Pro)分别比对照组降低了14.86%和48.75%,ρ(Sug)分别比对照组降低了18.77%和53.73%. 胁迫时间越长,丙二醛含量越高,长时间(12 d)的高温胁迫会对细胞造成永久伤害. 采用Logistic方程拟合生长曲线,40 ℃处理6 d组在恢复培养24 d后出现明显的超补偿,细胞密度增大,预计39 d后超过40 ℃处理3 d组. 高温诱发超补偿生长与自然界中藻类暴发的过程具有密切关系,这种内源性因素及藻体生理特征的变化可为湖泊水华发生的理论研究提供依据. 

Compensatory Growth Effect of Microcystis aeruginosa after High Temperature Stress

Abstract:Cyanobacteria blooms have become a global problem that destroy water environments. Frequent algae blooms are influenced by short-term changes in temperature. Some studies have shown that several microalgae, such as Pavlova viridis and Tetraselmis tetrethele, apparently show over-compensatory growth after UV-B or nutrient deficiency stress, but there is little information about the over-compensatory growth of microalgae after high temperature stress. To study the recovery growth of algae after high temperature stress, Microcystis aeruginosa was used as an experimental material. Two experiments were conducted. Three groups of M. aeruginosa were cultured under 40 ℃ respectively for 3,6, and 12 days before being transferred to 25 ℃ conditions with the same inoculation density as in the first experiments. The second experiment was set as the control, in which M. aeruginosa was cultured under 25 ℃ the entire time. Cell density, chlorophyll-a, carotenoid, incellular protein, carbohydrate and malondialdehyde were measured during the process. The results showed that under the high temperature stress, the growth of M. aeruginosa was inhibited significantly, with decreases of 81.08%, 97.89% and 90.31% in cell density, chlorophyll-a and carotenoid, respectively, on the 12th day. After the relief of the high temperature stress, the 40℃ for three days group showed over-compensation, with 30-day average compensation indexes of 1.63,0.90 and 2.12 for cell density, chlorophyll-a and carotenoid, respectively. The two groups of 40 ℃ for 6 and 12 days showed under-compensation. On the 30th day, the protein contents of the two groups were 14.86% and 48.75%, and the carbohydrate contents were 18.77% and 53.73% lower than the control, respectively. The longer the period of stress, the higher the content of malondialdehyde, and long period stress (12 days) could cause irreversible harm to algae cells. The growth curves fitted with Logistic model indicated that the 40 ℃ for 6 days group would show obvious over-compensation after 24 days recovery, and have a larger cell density than the 40 ℃ for 3 days group would have after the 39th day recovery. The over-compensation effect induced by high temperature stress was closely related to algal blooming processes. The endogenous factor and the change of algae physiological characteristics may provide basic support for lake algae bloom theoretical research.