Microbial Interactions: Competition

Microbial competition occurs when microorganisms in a shared environment compete for resources.

These resources can include nutrients, physical niche, and energy sources.

Exploitative competition occurs when certain microbes deplete shared nutrients faster than others, limiting the growth of slower competitors.

For example, siderophore-producing microbes outcompete rivals by absorbing iron more efficiently.

In interference competition, microbes actively harm their rivals. They use contact-independent systems that release toxins into the surrounding environment or contact-dependent systems that deliver toxins through cell-to-cell contact.

When one competitor consistently suppresses its rivals and exploits available nutrients, it can result in the competitive exclusion of the weaker strain.

However, over time, many microbes adapt to exploit distinct, non-overlapping resources or survival conditions.

For instance, phototrophic cyanobacteria and heterotrophic proteobacteria occupy different depths of the water column, avoiding direct competition and enabling stable coexistence. This phenomenon is known as niche partitioning.