Eco-friendly zinc oxide nanoparticles derived from Meyerozyma caribbica: Molecular docking-guided antibacterial action and novel alginate/ZnO/Fe3O4 biosorbent design for efficient azo dye removal

Zinc oxide nanoparticles (ZnONPS@Mc) were successfully synthesized for the first time using Meyerozyma caribbica to treat drug-resistant bacteria. The bacterial growth showed significant inhibition with increasing ZnONPS@Mc concentrations. The highest inhibition zone was determined against S. aureus (26.9 ± 0.7 mm) and E. coli (23.8 ± 0.7 mm), respectively. Using simulation analysis, the ZnONPS@Mc showed comparatively low binding energy against bacterial proteins (2XCT for S. aureus and 1MOQ for E. coli ). Novel alginate/ZnO/Fe 3 O 4 nanocomposite was fabricated and evaluated in Congo red (COR) sequestration for the first time. The biosorption capacity of anionic dye was pH dependent, where the microbead's surface presented a modified surface with different charges under acidic pH. From the optimal condition experiments, the adsorbent dose (0.05 g), pH (5.0), dye concentration (100 mg/l), and contact time (90 min) were detected. The microbeads displayed monolayer adsorption with a maximum biosorption efficiency of 204.08 mg/g for the alginate/ZnO/Fe 3 O 4 nanocomposite. The kinetic studies indicate that the biosorption process obeyed the pseudo-second-order fitting kinetics based on the higher correlation coefficient. The microbeads displayed pronounced shifts in their FTIR spectral patterns, while SEM analysis revealed a transition to a distinctly rough and glossy surface morphology following COR biosorption. The microbeads exhibited 70.4% removal efficiency after seven constitutive cycles due to irreversible sorption and the unavailability of adsorbent sites. These findings signify the potential of ZnONPS@Mc as a promising candidate for combating drug-resistant microbes, and the alginate/ZnO/Fe3O4 nanocomposite as a suitable biosorbent with a significantly higher sorption capacity compared to conventional adsorbents. • Meyerozyma caribbica fabricated zinc oxide nanoparticles for the very first time. • ZnONPS@Mc can tightly bind to pathogenesis-related proteins (2XCT and 1MOQ). • Alginate/ZnO/Fe 3 O 4 microbeads exhibit efficient sorption for Congo red dye. • Adsorption behavior was best obeyed by Langmuir isotherm and pseudo-second-order. • Excellent recycling of the developed nanocomposite for seven constitutive cycles.