Extracellular Metabolism Sets the Table for Microbial Cross-Feeding

Area of Science:

• Microbiology
• Ecology
• Biogeochemistry

Background:

• Cross-feeding, or nutrient transfer between microbial cells, is fundamental to community structure and function.
• This process relies on the externalization of diverse molecules, including nutrients, enzymes, and signaling compounds.
• These externalized molecules shape microbial interactions, influencing health and biogeochemical cycles.

Purpose of the Study:

• To review the major types of molecules involved in microbial cross-feeding.
• To explore the diverse functions of these externalized molecules.
• To examine how microbial physiology and environmental factors influence cross-feeding dynamics.

Main Methods:

• Literature review summarizing existing research on microbial cross-feeding.
• Analysis of examples from natural and synthetic microbial communities.
• Exploration of the interplay between molecular functions, microbial physiology, and environmental parameters.

Main Results:

• Cross-feeding involves actively secreted, passively excreted, and directly transferred molecules.
• Externalized molecules range from small compounds to macromolecules with diverse functions (e.g., nutrients, enzymes, toxins).
• Cross-feeding relationships can be cooperative, competitive, or exploitative, influenced by molecular attributes and environmental context.

Conclusions:

• Microbial cross-feeding is a complex phenomenon driven by diverse molecular exchanges.
• Understanding these interactions is key to comprehending microbial community dynamics and their ecological roles.
• The field of microbial cross-feeding is rapidly expanding, with much yet to be discovered.