Fig. 5: Gradient formation in biofilms.
Green-red color scale depicts physiological gradients whereas red-blue color scale depicts an environmental gradient. a Non-attached aggregates will experience three dimensional gradient formation in the direction from their surface toward the center (or opposite e.g., for metabolic by-products). This can create a stratification in growth leading to different sub-populations. b For surface attached biofilms, the same diffusion phenomena will occur and will also depend on the three-dimensional structure. Again, sub-populations can form due to gradient formations. c Conceptual figure showing the influence of the immediate microenvironment on biofilm physiological state. Aggregates in the top-right side are close to the external environment and are distant from highly O2-consuming neutrophils. Aggregates in the lower-left are surrounded by neutrophils that creates an anoxic microenvironment.
