What happens to the bacteria in biofilm as it matures over time?

As biofilm matures over time, there is a shift in the composition of bacteria present within it. The correct answer highlights that the biofilm becomes more gram-negative. Initially, early biofilm formation is typically dominated by gram-positive bacteria, which adhere to surfaces and establish the biofilm. As the biofilm matures, environmental conditions change, and different species of bacteria proliferate. This results in an increase in gram-negative bacteria, which are often more complex and can contribute to chronic infections.

This maturation process allows for increased diversity within the biofilm, as gram-negative bacteria often possess different metabolic capabilities, enabling them to thrive in the more anaerobic conditions that can develop as the biofilm thickens and becomes more structured. The successive layers can also create gradients of nutrients and oxygen, which favor the growth of gram-negative species.

In contrast, the other options do not accurately reflect the changes that occur in biofilms as they mature. The type of bacteria does change, gram-positive bacteria do not continually increase without limit, and the biofilm does not disintegrate completely; instead, it often becomes more resilient and complex over time.