Phenotypic and Genomic Differences Between Wildtype and Mutant Synechocystis sp. Strain PCC 6803 and Positive Phototaxis

Phenotypic and genomic differences between a wildtype non-motile strain and a motile mutant strain of Synechocystis sp. Strain PCC 6803 were determined by comparing the physical differences in their biofilm formation, their cell surface structures using scanning electron microscopy (SEM) and their genomes. The positive phototaxis of the motile mutant was also characterized using incandescent and fluorescent light sources and a variety of discrete wavelengths of light. It was found that the non-motile strain formed monolayer biofilms while the motile strain formed distinct pillars. SEM revealed that the non-motile cells had a more coarse surface than the motile cells. Four proteins that had different copy numbers between the two genomes were identified in genomic studies of the two species. Three of the proteins, related to twitching motility, exist in greater quantities in the motile strain than in the non-motile strain. Finally, it was determined that the motile mutant strain exhibits more phototaxis toward incandescent than toward fluorescent light. This might be due to the strain's specific interest in the wavelength of 660nm. All of these results suggest that the mutant strain is distinctively different from the wildtype, both in its phenotypic as well as its genomic characteristics.