biostudies-literatureKearney SMSimons Foundation821803https://www.ebi.ac.uk/biostudies/studies/S-EPMC8888907biostudies-literatureUnknown13Isolates of the marine picocyanobacteria, <i>Prochlorococcus</i> and <i>Synechococcus</i>, are often accompanied by diverse heterotrophic "contaminating" bacteria, which can act as confounding variables in otherwise controlled experiments. Traditional microbiological methods for eliminating contaminants, such as direct streak-plating, are often unsuccessful with this particular group of microorganisms. While they will grow in pour plates, colonies often remain contaminated with heterotrophic bacteria that can migrate through the soft agar. Additionally, axenic clones of picocyanobacteria can be recovered <i>via</i> dilution-to-extinction in liquid medium, but the efficiency of recovery is low, often requiring large numbers of 96-well plates. Here, we detail a simple and effective protocol Frontiers in microbiologyFilter Plating Method for Rendering Picocyanobacteria Cultures Free of Heterotrophic Bacterial Contaminants and Clonal.PMC8888907337262329108649394Chisholm SWCastro KGKearney SMCoe AfalseFilter Plating Method for Rendering Picocyanobacteria Cultures Free of Heterotrophic Bacterial Contaminants and Clonal.Isolates of the marine picocyanobacteria, <i>Prochlorococcus</i> and <i>Synechococcus</i>, are often accompanied by diverse heterotrophic "contaminating" bacteria, which can act as confounding variables in otherwise controlled experiments. Traditional microbiological methods for eliminating contaminants, such as direct streak-plating, are often unsuccessful with this particular group of microorganisms. While they will grow in pour plates, colonies often remain contaminated with heterotrophic bacteria that can migrate through the soft agar. Additionally, axenic clones of picocyanobacteria can be recovered <i>via</i> dilution-to-extinction in liquid medium, but the efficiency of recovery is low, often requiring large numbers of 96-well plates. Here, we detail a simple and effective protocol 2022-01-01T00:00:00Z20222025-04-18T12:10:31.937Z2025-04-06T21:48:36.37ZS-EPMC88889073525093710.3389/fmicb.2022.821803