Effects Of Bisphenol A And Nonylphenol On Photosynthetic Efficiency And Growth Of Two Microalgae

Bisphenol A(BPA)and Nonylphenol(NP)are typical environmental hormones,widely used in industrial production.With the aggravation of industrial activities,they are discharged into the aquatic ecosystem in large quantities,attracting widespread attention.In this study,Chlorella pyrenoidosa and Scenedesmus bijuba were used as experimental materials.Firstly,the cell density;chlorophyll a and F_V/F_Mof the algae after adding BPA and NP were assessed.The transcriptome response of Chlorella pyrenoidosa(72 h 0,0.1 and 10 mg/L BPA treatment)was studied by transcriptome sequencing.the effects of BPA and NP on Chlorella pyrenoidosa and Scenedesmus bijuba were assessed based on growth and photosynthetic efficiency.It provides a scientific basis for determining the safety threshold of BPA and NP in water environment and evaluating their toxic effects in water ecosystem and provide information for effective prevention and control of environmental hormone pollution.The results of this study showed as followings:(1)Hormesis occurred in Chlorella pyrenoidosa and Scenedesmus bijuba exposed to BPA and NP.At 0.01 mg/L and 0.1 mg/L BPA treatment group for 72 h,the cell density of Chlorella pyrenoidosa increased by 7.8%and 19.3%,and the cell density of Scenedesmus increased increased by 30.8%and 19%.When the concentration of the treatment group was more than 1mg/L,the density of algal cells decreased with the increase of the concentration.In the NP treated group,after 72hours of treatment with 0.01 mg/L and 0.05 mg/L,the cell density of Chlorella pyrenoidosa increased by 42.5%and 24.5%,and the density of Scenedesmus increased increased by 21.4%and 30.4%,respectively.When the treatment group was more than 0.5 mg/L,the density of algal cells decreased with the increase of concentration.(2)At low concentration of NP and BPA,the F_V/F_Mvalue had no significant change with that of the control group,and did not affect their photosynthesis.While in the high concentration treatment group,the F_V/F_Mvalue was significantly reduced,and photosynthesis was inhibited.(3)Transcriptome analysis of Chlorella pyrenoidosa showed:Most genes of Chlorella pyrenoidosa treated with low concentration BPA did not change,the genes of nucleotide transport,single-organism transport and cell respiratory were up-regulated.Among them,The results of real-time PCR showed that ATPase and NADH dehydrogenase were up-regulated.The inhibition of genes related to TCA cycle,Glycolysis,Fatty acid metabolism and Mitochondrial Electron Transport was observed under the effect of high concentration BPA.