An industrial strain of a unicellular green algae Parachlorella nurekis 1904 KIEG deposited in the Culture Collection of Algae and Protozoa (CCAP), Scottish Marine Institute, Dunbeg, OBAN, Argyll, PA37 IQA, Scotland, UK, CCAP No. 259/1. A method for eradication of at least one of cyanobacteria, bacteria and fungi comprises treating the at least one of cyanobacteria, bacteria and fungi with an industrial strain of the unicellular green algae Parachlorella nurekis 1904 KIEG deposited in the Culture Collection of Algae and Protozoa (CCAP), Scottish Marine Institute, Dunbeg, OBAN, Argyll, PA37 1QA, Scotland, UK, CCAP No. 259/1.