Topic overview

Start with the big picture

Normal microbiota can limit pathogen colonisation, produce vitamins, and help shape immune responses. Gut microbes also ferment fibre into short-chain fatty acids and participate in the metabolism of drugs and other substances. Beyond the body, microorganisms support food fermentation, industrial production, environmental cycles, sewage treatment, and bioremediation; microbial tools also contribute to diagnostics and biotechnology. At the same time, pathogenic microbes cause disease, while opportunistic infections can arise when host defences or barriers are compromised. Virulence factors, biofilms, antimicrobial resistance, and post-infectious effects are among the clinical challenges explored in this topic. Together, these roles show why understanding microorganisms requires attention to both their benefits and their risks.