光照对微囊藻比重的影响及其调控机制

The Effect of Light on the Specific Density of Microcystis and Its Regulation Mechanism

富营养化湖泊中,浮力调控机制是微囊藻在种间竞争中占据优势的重要原因,而其浮力则受细胞比重的调控。该文探究了微囊藻的比重及其调控因子对光照强度的长期和短期响应。结果表明,10 d的长期实验中,在0~5500 lx范围内,光照强度越强,比重越大,且与光照强度呈正相关,其中5500 lx光强下微囊藻培养10 d后的比重增量是200 lx的2.73倍。随着光照强度增加,在比重的调控因子中胞内碳水化合物含量增加,伪空胞含量和胞内蛋白质含量减少。相关性分析显示,碳水化合物增加和伪空胞减少是比重增加的主要原因,尤其是碳水化合物的积累增加了微囊藻的下沉动力。24 h的短期实验结果显示,在光周期内所受光照强度越强,微囊藻的碳水化合物含量积累越多,其比重明显上升;经历暗周期后,光周期内光照强度越强,胞内碳水化合物消耗越多,其比重下降更明显。该研究显示长期和短期条件下高光强都能诱导微囊藻比重增加,但在短期高光强作用下胞内碳水化合物含量虽然积累很快,但同时也促进了其在暗周期的消耗,这为进一步揭示微囊藻的垂直迁移的形成机制提供了参考。

In eutrophic lakes,the buoyancy regulation mechanism is an important reason for the predominance of Microcystis in interspecific competition,and its buoyancy is regulated by the specific density of cells.This study explored the longterm and short-term response of Microcystis and its regulatory factors to light intensity.The results showed that in the longterm experiment of 10 d,the stronger the light intensity was,the greater the specific density was.Therefore,the specific density was positively correlated with light intensity in the range of 0~5500 lx.The specific density of the group cultured under5500 lx is 2.73 times that of 200 lx.As the light intensity increased,intracellular carbohydrate content increased,while gas vesicles content and intracellular protein content decreased.Correlation analysis showed that the increase in carbohydrates and the reduction of gas vesicles were the main reasons for the increase in specific gravity,especially the accumulation of carbohydrates increased the sinking power of Microcystis.The results of 24 h short-term experiment showed that the stronger the light intensity in the photoperiod was,the more the carbohydrate content of Microcystis accumulated,and the specific gravity increased significantly.After the dark cycle,the stronger the light intensity in the photoperiod was,the more the intracellular carbon is consumed,so the more the specific gravity decreases.This study shows that high light intensity can induce the increase of the specific density of Microcystis in both long-term and short-term conditions.The accumulation of intracellular carbohydrate content in the short-term high light intensity is rapid,but it also promotes its consumption in the dark cycle,which provides a reference to further reveal the formation mechanism of the vertical migration of Microcystis.