In this thesis the growth patterns of certain bacterial colonies are studied through numerical simulations of a continuous model, describing the growth of the colony. The objective was to construct a mathematical model capable of recreating observed growth patterns and thus try to gain some insight into the dynamics of bacterial growth. The model constructed in this thesis consists of a set of reaction-diffusion equations describing the evolution of the bacterial colony viewed as a continuous body rather than many individual bacteria. This approach was partially successful, in the sense that similar patterns to those observed in experiments were indeed observed in the simulations. On the other hand, the model was found inadequate in the sense that it could not satisfactory account for the initial rapid expansion of the colony in combination with the fact that the expansion is severely diminished after a few days. From the results it could be concluded that in order to get a satisfactory description of the complete evolution of the bacterial colonies studied here a more sophisticated theory for the diffusion processes is needed. The main conclusion is that the changes in the growth patterns are most likely due to genetic changes, or ’mutations’, in some bacteria causing the mutated bacteria to diffuse faster. There is an upper bound for the mutation frequency in order to get the patterns seen in experiments. The biological mechanism behind this phenomenon could be that the bacteria that mutate lose their pili enabling them to diffuse faster.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kth-44034 |
| Date | January 2011 |
| Creators | Palm, Oskar |
| Publisher | KTH, Teoretisk fysik |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | Trita-FYS, 0280-316X ; 15 |
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