Green Synthesis of Zinc Oxide Nanoparticles Using an Aqueous Extract of Punica granatum for Antimicrobial and Catalytic Activity.

The peel aqueous extract of Punica granatum was utilized to fabricate zinc oxide nanoparticles (ZnO-NPs) as a green approach. The synthesized NPs were characterized by UV-Vis spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy, which was attached to an energy dispersive X-ray (SEM-EDX). Spherical, well arranged, and crystallographic structures of ZnO-NPs were formed with sizes of 10-45 nm. The biological activities of ZnO-NPs, including antimicrobial and catalytic activity for methylene blue dye, were assessed. Data analysis showed that the antimicrobial activity against pathogenic Gram-positive and Gram-negative bacteria, as well as unicellular fungi, was observed to occur in a dose-dependent manner, displaying varied inhibition zones and low minimum inhibitory concentration (MIC) values in the ranges of 6.25-12.5 µg mL-1. The degradation efficacy of methylene blue (MB) using ZnO-NPs is dependent on nano-catalyst concentration, contact time, and incubation condition (UV-light emission). The maximum MB degradation percentages of 93.4 ± 0.2% was attained at 20 µg mL-1 after 210 min in presence of UV-light. Data analysis showed that there is no significant difference between the degradation percentages after 210, 1440, and 1800 min. Moreover, the nano-catalyst showed high stability and efficacy to degrade MB for five cycles with decreasing values of 4%. Overall, P. granatum-based ZnO-NPs are promising tools to inhibit the growth of pathogenic microbes and degradation of MB in the presence of UV-light emission.

Evaluate the Toxicity of Pyrethroid Insecticide Cypermethrin before and after Biodegradation by Lysinibacillus cresolivuorans Strain HIS7.

Herein, bacterial isolate HIS7 was obtained from contaminated soil and exhibited high efficacy to degrade pyrethroid insecticide cypermethrin. The HIS7 isolate was identified as Lysinibacillus cresolivuorans based on its morphology and physiology characteristics as well as sequencing of 16S rRNA. The biodegradation percentages of 2500 ppm cypermethrin increased from 57.7% to 86.9% after optimizing the environmental factors at incubation condition (static), incubation period (8-days), temperature (35 °C), pH (7), inoculum volume (3%), and the addition of extra-carbon (glucose) and nitrogen source (NH4Cl2). In soil, L. cresolivuorans HIS7 exhibited a high potential to degrade cypermethrin, where the degradation percentage increased from 54.7 to 93.1% after 7 to 42 days, respectively. The qualitative analysis showed that the bacterial degradation of cypermethrin in the soil was time-dependent. The High-Performance Liquid Chromatography (HPLC) analysis of the soil extract showed one peak for control at retention time (R.T.) of 3.460 min and appeared three peaks after bacterial degradation at retention time (R.T.) of 2.510, 2.878, and 3.230 min. The Gas chromatography-mass spectrometry (GC-MS) analysis confirmed the successful degradation of cypermethrin by L. cresolivuorans in the soil. The toxicity of biodegraded products was assessed on the growth performance of Zea mays using seed germination and greenhouse experiment and in vitro cytotoxic effect against normal Vero cells. Data showed the toxicity of biodegraded products was noticeably decreased as compared with that of cypermethrin before degradation.