Nutrient diffusion governs S. cerevisiae colony dynamics: Monitoring by optical coherence tomography

Area of Science:

• Microbiology
• Biophysics

Background:

• Microbial colonies form structured aggregates on solid supports, exhibiting complex spatial and temporal growth dynamics.
• Large colonies, such as those of Saccharomyces cerevisiae, present monitoring challenges due to their dimensions.

Purpose of the Study:

• To non-destructively assess the growth of Saccharomyces cerevisiae colonies over two weeks using optical coherence tomography (OCT).
• To investigate the impact of nutrient concentration and agar gel thickness on colony development.

Main Methods:

• Utilized optical coherence tomography (OCT) for non-destructive monitoring of yeast colony growth.
• Varied nutrient concentrations and agar gel thicknesses to observe effects on colony morphology.

Main Results:

• Colony radial growth initially appeared linear but decreased over time.
• Vertical expansion showed asymptotic behavior, influenced by agar gel thickness.
• Volume expansion was biphasic, characterized by an initial exponential phase followed by slower growth.
• Nutrient diffusion was identified as a critical factor governing colony expansion dynamics.

Conclusions:

• Diffusion limitations significantly influence microbial colony development and shape as nutrients deplete.
• Optical coherence tomography (OCT) provides valuable quantitative data complementing traditional biological observations.
• An empirical law was proposed to describe yeast colony volume increase under diffusion constraints.