The development of environmentally benign procedures for the synthesis of metallic nanoparticles (NPs) is a vital aspect in bionanotechnology applications for health care and the environment. This study describes the biosynthesis of Ag, Co, Ni, and Zn NPs by employing nanobiofactory Proteus mirabilis strain 10B. The physicochemical characterization UV-visible spectroscopy, scanning electron microscopy-energy-dispersive X-ray microanalysis (EDX), X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS) technique including ζ potential, and polydispersity index (PDI) confirmed the formation of pure, stable monodisperse quasi-spherical oxide NPs of corresponding metals. The antimicrobial activity of biofabricated NPs was assessed against Gram-negative and Gram-positive bacteria, biofilm, yeast, mold, and algae via a well diffusion method. The results displayed significant antagonistic activity in comparison to their bulk and commercial antibiotics. Interestingly, the combined NPs exhibited promising synergistic biocide efficiency against examined pathogens which encourages their applications in adjuvant therapy and water/wastewater purification for controlling multiple drug-resistant microorganisms. To the best of our knowledge, no previous study reported the synthesis of semiconductor NPs by Proteus mirabilis and the biocide potency of combined NPs against a broad spectrum of pathogens not reported previously.

Natural environment is a wealthy source of bionanofactories that invested in green approaches as the fabrication of biomimetic nanomaterials. The current study points out the importance of microbial activity in metal bioremediation, green synthesis of NPs, and global biogeochemical cycles of bioactive metals as well. It describes for the first time the synchronous biosynthesis of zero- (intracellular) and one-dimensional (extracellular) copper oxide nanoparticles (CuO-NPs) viaProteus mirabilis10B. This bionanofactory represents key location of reduction and stabilization, and its exopolysaccharide additionally provides nucleation and growth site for CuO-NPs. The as-synthesized CuO-NPs were characterized; UV-Vis spectroscopy revealed surface plasmon resonance at 275 and 430 nm for intracellular and extracellular CuO-NPs, respectively. XRD reflected crystalline, pure phase monoclinic structure CuO-NPs. EDX illustrated strong copper signal with atomic percentages 32.3% (intracellular) and 14% (extracellular) CuO-NPs. However,ζ-potential recorded −62.5 and −43.8 mV with PDI 0.207 and 0.313 for intracellular and extracellular CuO-NPs, respectively, confirming the colloidal stability and monodispersity. Moreover, TEM micrographs depicted quasi-spherical intracellularly sequestered CuO-NPs (10 nm). Unexpectedly, extracellular CuO-NPs exhibited rod-, needle-, and wire-shaped with 17–37.5 nm in width and 112–615 nm in length. The antagonistic activity of both types of CuO-NPs was evaluated against Gram-negative and Gram-positive bacteria (aerobic and anaerobic), biofilm, yeast, mold, and algae. The potent antagonistic efficacy of CuO-NPs was displayed which encourages its utilization in controlling microbial contamination. Finally, the promising metabolic activity ofProteus mirabilis10B can be exploited in simultaneous and beneficial applications for human and the surrounding ecosystem.

It is preferable to use an organism to produce more than one product at the same time. So, the aim of this study was to investigate the ability of bioflocculant‐producing Bacillus mojavensis strain 32A as a nanosilver synthesizer beside bioflocculant production. To achieve this target, three media, nutrient broth, bioflocculant‐producing medium, and pure bioflocculant, were tested. Produced nanosilver was characterized by UV‐vis, XRD, and TEM. In all cases, the results demonstrated that UV‐vis showed a peak at ~420 nm corresponding to the plasmon absorbance of nanosilver. XRD spectrum exhibited 2θ values corresponding to the silver nanocrystal that is produced in hexagonal and cubic crystal configurations. TEM confirmed formation, size, shape, and morphologies of nanosilver particles. The results emphasized that purified bioflocculant has the ability to produce anisotropy clusters of nanosilver ranging in size from 6 to 72 nm proving that the bioflocculant functioned as reducing and stabilizing agent in nanosilver synthesis.

Environmental pollution is a global phenomenon and troublesome fact that poses a grave risk to all living entities. Via coupling carbonaceous feedstocks with outstanding microbial activity, kinetic experiments were established using the consortium of Proteus mirabilis and Raoultella planticola, biochar-derived sunflower seed husk (SHB) and rice straw (RSB), and their composites, which investigated at 30 °C (150 rpm) to eliminate 700 mg L⁻¹ lead (120 h) and phenol (168 h) from synthetic wastewater. The derived biochars physicochemical properties of were studied. According to adsorption capacity (q_e), consortium-SHB composites and consortium-RSB composites removed lead completely (70 mg g⁻¹) within 48 h and 66 h, respectively. Besides, phenol was remediated entirely after 42 h and 48 h by both composite systems (69.90 mg g⁻¹), respectively, comparing with bacterial consortium only or parent SHB and RSB. Moreover, four kinetic models were studied to describe the bioremediation process. Fractional power and Elovich models could be recommended for describing the adsorption kinetics for lead and phenol removal by the studied biomaterials with high correlation coefficient (R² ≥ 0.91 for Pb²⁺ and ≥ 0.93 for phenol) and lower residual root mean square error (RMSE) and chi-square (X²). Overall, bacterial consortium-biochar composites exhibited greater remediation of lead and phenol than the sum of each single bacterial consortium and biochar systems; reflecting synergistic interaction of adsorptive capability of biochar and metabolic performance of bacterial consortium, as denoted by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The current study addressed the successful design of employing functional remediating consortium immobilized on waste biomass-derived biochar as a conducive alternative eco-sorbent and economic platform to detoxify organic and inorganic pollutants.