Genetic and biochemical analyses of pigmented ring formation in colonies of Pseudoalteromonas sp. 15DK1

Microbial growth on solid media can lead to the formation of a diverse array of colony morphologies, and these morphologies can be useful in understanding how microbes grow and respond to various challenges presented by such a dense and dry style of growth. A new isolate from seawater in Garbage Beach, Pseudoalteromonas sp. 15DK1, was isolated in the laboratory and found to form concentric pigmented rings. A genetic approach was undertaken to identify potential biological aspects of this pattern formation, including mechanisms that drive the formation of the rings from pigment-producing strains, as well as the production of the pigment itself. Mutants were isolated that show deficiency in ring formation, which may reveal information about how these concentric rings are formed. Extraction of the pigments revealed that different pigments may be produced during different growth phases on solid media, or in specific conditions in liquid media. Future analyses will be necessary to determine the identity of the pigments, as well as how they influence the formation of the ringed colonies.