MICROBIAL GROWTH PATTERNS: FRACTAL AND KINETIC CHARACTERISTICS OF PATTERNS GENERATED BY A COMPUTER MODEL TO SIMULATE FUNGAL GROWTH

Abstract

This investigation is concerned with the description of patterns that are generated by a computer model that mimics fungal colonies. The computer model is based on parameters that can be related to biological processes in a fungus, i.e., branching, tip growth, and next neighborhood behavior (repulsion or attraction between cells). We study the systematic variations of parameter values in the model quantitatively by the fractal dimension D as a function of the diameter (L), the iteration (I), and the mass (M) of the simulated structures. We find a very different increase of D as a function of L, I, or M during the pattern development, which depends on the chosen parameter values. Therefore, the variation of parameter values in the model helps us to understand which biological processes might be affected, leading to different fungal growth patterns: e.g. the model can mimic the concentration dependent griseofulvin influence on the morphology by variation of rather straight or rather zigzag growing tips as it is found experimentally for the strain Sordaria macrospora. Analyzing the model leads to the assumption that especially the study of D as a function of the diameter and the iteration will be very fruitful for a detailed understanding of microbial pattern formation. The correlation between geometrical and kinetic properties of the patterns generated by the model are shown. (The experimental results and parts of the growth model were published previously in a doctoral thesis.)