Diffusion through a Double-Sided Plate: Development of a Method to Study Alga-Bacterium Interactions.

Bacteria and algae isolated from a wastewater oxidation pond were inoculated onto opposing surfaces of double-layer agar plates (Lutri plates) to determine the usefulness of such plates for studying microbial interactions. The altered growth characteristics of various algae depending on the species of bacteria on the adjacent medium surface indicated that there was diffusion of extracellular products through the agar, suggesting that this simple assay can be used for screening potential interactions of actively growing organisms.