Microalgae-based removal and biodegradation of antibiotics: mechanisms, synergistic consortia, and engineering prospects.

Antibiotic pollution in aquatic environments drives the spread of resistance genes and threatens ecosystem health. Microalgae offer a dual-function platform that both senses antibiotic stress and actively removes these contaminants. This review synthesizes current knowledge on microalgae-based antibiotic removal and biotransformation, emphasizing the integration of biosorption, enzyme-mediated transformation-primarily via cytochrome P450 and nitroreductase-and co‑metabolic processes. We highlight the phycosphere as a dynamic interface where symbiotic bacteria enhance algal survival and pollutant removal, while also modulating the enrichment and dissemination of resistance genes. Algal-bacterial granular sludge systems illustrate the practical potential of this synergy, achieving efficient antibiotic removal and suppression of resistance propagation. Emerging tools such as immobilization, synthetic biology, and machine learning show potential to further improve system robustness and may facilitate precision process control, although their scalability and long-term performance remain to be validated. By linking fundamental mechanisms with engineering strategies, this review provides a framework for developing sustainable, low-carbon bioremediation technologies aligned with global antimicrobial resistance action plans.