Synthesis, characterization and biological investigation of zinc nanoparticles using Acacia modesta Wall. leaves.

The study aimed to synthesize zinc nanoparticles (Zn-NPs) using an aqueous extract derived from Acacia modesta Wall. leaves. Several characterization techniques were employed to confirm the successful formation of zinc nanoparticles. UV-visible spectrophotometry indicated a peak at 374 nm, validating the bioreduction process. Scanning electron microscopy (SEM) was utilized to analyze the morphology, transmission electron microscopy (TEM) to determine particle size and shape, X-ray diffraction (XRD) for crystalline structure analysis, energy-dispersive X-ray spectroscopy (EDX) for elemental composition and Fourier-transform infrared spectroscopy (FTIR) to identify functional groups. The synthesized Zn-NPs demonstrated remarkable antibacterial activity against Escherichia coli (95% inhibition) and moderate antifungal activity against Candida albicans (70% inhibition). In phytotoxicity tests, the Zn-NPs exhibited a 55% reduction in the growth of Lamina minor at the highest dilution (1000 µl). Based on these findings, the study concluded that the green-synthesized Zn-NPs hold great potential as effective antibiotics against pathogenic bacteria and could be utilized in various industrial and agricultural applications.

Bioremediation of soil contaminated with toxic mixed reactive azo dyes by co-cultured cells of Enterobacter cloacae and Bacillus subtilis.

Azo dyes, known for its toxicity and mutagenicity, are used by textile industries. Bioremediation serves the best alternative treatment process due to its eco-friendly nature and cost-effectiveness. Degradation using individual bacteria promotes azo dye removal, while the degradation is enhanced using the immobilization method. Bio-carrier promotes the attachment of the bacterial strains and increases azo dye degradation. The present study focuses on the biodegradation of Reactive Red (RR), Reactive Brown (RB), Reactive Black dye (RBL), and mixed dyes in a soil slurry bioreactor containing free cells, co-culture, and immobilized cells. The physico-chemical analysis and soil characteristics were determined. The free cells of Bacillus cereus showed degradation of azo dyes - 79.42 ± 0.03% RR, 78.78 ± 0.02% RBL; 70.76 ± 0.03% RB, and 84.89 ± 0.05% of mixed dyes respectively. Enterobacter cloacae free cells resulted in degradation of 72.87 ± 0.01% RR, 75.21 ± 0.01% RBL, 74.50 ± 0.02% RB, and 73.39 ± 0.04% mixed dyes respectively. Co-cultured bacterial strains resulted in 77.18 ± 0.03% RR, 80.27 ± 0.02% RBL, 76.97 ± 0.02% RB and 86.29 ± 0.05% mixed dyes respectively. The immobilization of Bacillus cereus and Enterobacter cloacae on 2% corn starch resulted in 98.4 ± 0.01% degradation of RR, 89.8 ± 0.09% degradation of RB, 99.4 ± 0.05% of RBL, and 98.1 ± 0.08% of mixed reactive dyes respectively.