Extracellular polymeric substances in indigenous microalgal-bacterial consortia: advances in characterization...

Extracellular polymeric substances (EPS) synthesized by indigenous microalgal-bacterial consortia (IMBC) play multifunctional roles in enhancing wastewater treatment efficiency, nutrient sequestration, and ecological system stability. This comprehensive review critically evaluates state-of-the-art analytical methods for characterizing EPS composition, physicochemical properties, and functional dynamics, including colorimetry, Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). While these methods provide critical insights into EPS structure-function relationships, challenges persist in resolving spatial heterogeneity, real-time secretion dynamics, and molecular-scale interactions within complex IMBC systems. Emerging technologies such as expansion microscopy (ExM), electrochemical impedance spectroscopy (EIS), and integrated multi-omics approaches are highlighted as transformative tools for in situ EPS profiling, offering nanoscale resolution and temporal precision. By synthesizing these innovations, this review proposes a multidisciplinary framework to decode EPS-mediated microbial symbiosis, optimize IMBC performance, and advance applications in sustainable bioremediation, bioenergy, and circular resource recovery.