ORIGINAL ARTICLE Effects of Copper and Cadmium on the Protein Profile and DNA Pattern of Marine Microalgae Chlorella salina and Nannochloropsis salina Soad M. Mohy El-Din 1 & Mohamed S. Abdel-Kareem 1 Received: 1 July 2019 /Accepted: 30 December 2019/ # Springer Nature Switzerland AG 2020 Abstract Toxicity of copper (Cu +2 ) and cadmium (Cd +2 ), as pollutants, in sea water was evaluated using two microalgae, Chlorella salina and Nannochloropsis salina. Experiments were carried out for 96 h with the two heavy metals causing changes in the growth, protein pattern and DNA profile of the studied algae. Lethal concentration (LC 50 ) values for Cu +2 and Cd +2 indicated that both C. salina and N. salina are affected by Cu +2 than Cd +2 . Polyacrylamide gel electrophoresis (SDS PAGE) was used for the separation and iden- tification of proteins. The treatment of the two marine microalgae with Cu +2 and Cd +2 prompted the disappearance of a single band of C. salina and four bands of N. salina protein profiles, compared to control. From the phylogenetic tree that resulted, moderate genetic similarity was detected for untreated and heavy metals treated C. salina samples (52%), while low genetic similarity was detected for untreated and heavy metals treated N. salina samples (10%). Random amplified polymorphic DNA (RAPD) technique was used for investigating variability in genetic pattern of DNA in both C. salina and N. salina. In this regard, from the genetic pattern of DNA, it was concluded that both copper and cadmium induced some genotoxic influences in both algal species, with more genotoxic effect of copper than cadmium. Keywords Marine microalgae . Heavy metal stress . Lethal concentration . Protein profile . RAPD marker 1 Introduction The significant development of the industry and the increased utilization of heavy metals has caused rising of different problems in the environment, especially in sea, river and lake waters. Environmental Processes https://doi.org/10.1007/s40710-019-00419-1 * Soad M. Mohy El-Din dr.soad_mohi@hotmail.com 1 Department of Botany and Microbiology, Faculty of Science, Alexandria University, Alexandria, Egypt