Microbial growth patterns described by fractal geometry

Area of Science:

• * Biology
• * Microbiology
• * Biophysics

Background:

• * Fractal geometry has elucidated inorganic system growth, including aggregation and dendritic patterns.
• * Previous biological applications include lung airways, protein structures, and protein surface irregularity.
• * Microbial growth patterns have not been previously analyzed using fractal geometry.

Purpose of the Study:

• * To apply fractal geometry to investigate the growth patterns of two microbial species: Streptomyces griseus and Ashbya gossypii.
• * To establish fractal dimensions as a novel growth parameter for microbial colonies.
• * To analyze the transition of microbial colonies from mass to surface fractal structures during growth.

Main Methods:

• * Application of fractal geometry concepts to microbial colony growth.
• * Utilization of two distinct box-counting methods to evaluate fractal dimensions.
• * Analysis of aggregates using box-counting applied to both the entire mycelial mass and its surface.

Main Results:

• * Demonstrated fractal aggregates in biological systems, with individual cells as the smallest aggregating units and colonies as aggregates.
• * Identified a fractal dimension (D) that describes the global structure of branched mycelia, increasing up to 1.5 during growth.
• * Evaluated fractal dimensions (D) ranging from 1.3 to 2 using box-counting methods.
• * Observed a shift in mycelial structure from mass fractal to surface fractal during growth.

Conclusions:

• * Fractal geometry provides a novel framework for understanding microbial colony development.
• * The fractal dimension (D) serves as a quantifiable growth parameter for microbial systems.
• * Microbial colony morphology dynamically transitions from a mass-dominated to a surface-dominated fractal structure as growth progresses.