Ace the Microbiology & Immunology 6400 Challenge 2026 – Dive into Epic Intermicrobial Interactions!

Cross feeding describes a situation where one microbe releases a nutrient that another microbe uses to support growth. This kind of intermicrobial interaction creates a metabolic handoff in communities—one organism supplies a compound like a vitamin, amino acid, or a metabolic byproduct that the other cannot synthesize or readily obtain on its own. This exchange helps diversify and stabilize microbial ecosystems such as biofilms or the gut microbiota.

Syntrophy is related but more specific: it refers to a tightly coupled, mutually dependent metabolic partnership where the growth of each organism hinges on the metabolic activities of the other. In that case, the interaction is often essential for energy flow and survival under certain conditions.

Predation involves one organism consuming another for nutrients, not sharing resources. Competition is when organisms struggle for the same resource without providing nutrients to each other.

So producing a nutritional source for another is best described as cross feeding.