Microencapsulation of Pseudomonas fluorescens for cyanide biodegradation in mineral waste

• Pseudomonas fluorescens was microencapsulated using spray drying. • Spray-drying microcapsules preserved viability for cyanide biodegradation. • Spherical microcapsules with a modal particle size distribution. • Rehydrated powders exhibited stable flow and shear thinning behavior. • Microcapsules suitable for cyanide contaminated waste bioremediation. Cyanide residues represent a critical environmental concern, particularly in mining and metallurgical industries. This study introduces a novel approach for cyanide bioremediation through the microencapsulation of Pseudomonas fluorescens adapted to degrade high cyanide concentrations (up to 10000 ppm). Spray-drying was employed as an encapsulation technique to preserve bacterial viability and functionality, producing stable powder formulations that facilitate storage and handling. Physicochemical characterization revealed encapsulation yields exceeding 90%, with long-term stability under storage conditions. The microcapsules exhibited water activity below 0.1 and a moisture content of 2.9%. Fourier-transform infrared (FT-IR) and Transmission electron microscopy (TEM) analyses confirmed successful bacterial encapsulation, while Scanning electron microscopy (SEM) micrographs showed spherical particles with rough surfaces and no visible cracks. Release profiles assessed via 5-Cyano-2, 3-ditolyl tetrazolium chloride (CTC) staining validated respiratory activity and bacterial viability after 20 h of encapsulation. These findings demonstrate that spray-drying microencapsulation as a technologically viable approach for maintaining bacterial performance in bioremediation applications.