| Plaque Notes | After 24 hours of incubation at 37°C, the average plaque size was 1.325 mm. After 48 hours of incubation the average size varied depending on the density of phage. For phage with ample room to grow (less then approximately 350 plaque forming units), the average size was 4.76 mm. Plates that contained more then approximately 350 plaques were too difficult to measure because they ran into each other. After 72 hours of incubation with ample room to grow plaques grew to an average of 6.2 mm. After 72 hours of incubation Optimus ceased growth. The morphology of phage Optimus was very consistent once variations due to plaque density were accounted for. After 24 hours, a clear center was visible with a turbid area around that clear center, but the edges were not clearly defined. Furthermore, plaques near the edge of the plate had an oblong shape, resembling a comet tail. This comet tail always faced the edge of the plate while the clear center was closest to the middle of the plate. After 48 hours of incubation at 37°C not only was there a growth in plaque size, but there was also a more defined morphology. The edges of both the clear center and the turbid outer ring were more definite. Growth occurred in the turbid outer ring while the size of the clear center remained the same. The comet tail and clear center remain altered towards the edge and middle of the plate, respectively. Additionally, a higher concentration of bacteria surrounding the plaque was suggested by the lighter, more concentrated color. As the plaques grew in size, the relatively vague halo of bacteria concentration increases as suggested by the lighter coloration becoming more noticeable with the increase in plaque size. After 72 hours of incubation there was a slightly altered morphology, and an increase in bacteria surrounding the plaque as indicated by a lighter, more concentrated color. Under certain concentrations, around 250 plaques, the plaques formed another defined ring. The plaque morphology still contains a small clear center with a turbid ring and the comet tail effect; however, at 72 hours there were two additional rings on the outside of the original clear center and thick turbid ring. The first of these additional rings was more turbid then the second. In smaller plaque concentrations this last ring was faintly visible, but its edges were not as defined as those found in higher concentrations. Plates with more then approximately 300 plaques ran into each other after 72 hours so this morphology did not develop. After 72 hours of incubation, size and morphology of Optimus remain constant. |
