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The present work focused on the isolation of a bacterial strain multi-resistant to heavy metals with a high potential for reducing hexavalent chromium (Cr(VI)) and studied its Cr(VI) removal performance in immobilized state and the mechanisms involved. Bacterial isolate was identified as Bacillus safensis CCMM B629 (B. safensis), is able to completely reduce 50, 100 and 200 mg/L of Cr(VI) after 24, 48 and 120 h, respectively under optimized conditions of pH 7 and 30°C. The coexistence of nitrates, cadmium and mercury inhibits reduction, while copper and iron significantly improve removal efficiencies. Additionally, the presence of electron donors such as glycerol, glucose and citrate significantly increases bioreduction rate. Cells immobilized in alginate beads successfully reduced Cr(VI) compared to free cells, showing the performance of biobeads in Cr(VI) reduction. Membrane fraction exhibited highest rate of Cr(VI) reduction (65%) compared to other cellular components, indicating that Cr(VI) reduction occurred primarily in cell membrane. Further characterization of Cr(VI) removal by B. safensis cells using scanning electron microscopy and energy-dispersive X-ray (SEM-EDX) analysis showed its ability to reduce and adsorb Cr(VI), confirming that hexavalent chromium was taken up successfully on bacterial cell surfaces. Based on Fourier transform infrared spectroscopy analysis (FTIR), hydroxyl, carboxyl, amide, and phosphoryl functional groups participated in combination with Cr(III). In conclusion, B. safensis is a bacterium with great potential for Cr(VI) removal, and it is a promising and competitive strain for use in bioremediation of Cr(VI) contaminated industrial effluents. [ABSTRACT FROM AUTHOR]

In this work, we describe the synthesis of novel Ruthenium (II) complex-based salen Schiff bases. The obtained Ruthenium (II) complexes are characterized using usual spectroscopic and spectrometric techniques, viz., IR, UV-Vis, NMR (1H and 13C), powder X-ray diffraction, and HRMS. Further techniques, such as DTA-TGA and elemental analysis, are used to well establish the structure of the obtained complexes. Octahedral geometries are tentatively proposed for the new Ru(II) complexes. The measured molar conductance for the Ruthenium (II) complexes shows their electrolytic nature (4.24–4.44 S/m). The new Ru(II) complexes are evaluated for their antioxidant and antibacterial activities. The DPPH radical scavenging, FRAP, and total antioxidant capacity (TAC) assays show that the obtained complexes are more potent than the used positive control. They also exhibit promising antibacterial responses against pathogen bacteria: [RuH2L3Cl2] exhibits an important inhibition against Bacillus subtilis DSM 6633, with an inhibition zone of 21 ± 1.41 mm with an MIC value of 0.39 mg/mL, and Proteus mirabilis INH, with 16.50 ± 0.70 mm and an MIC value of 0.78 mg/mL, while [RuH2L2Cl2] exerts interesting antibacterial effects versus Bacillus subtilis DSM 6633 (21 ± 1.41 mm) and Proteus mirabilis INH (25.5 ± 0.70 mm) with equal MIC values of 0.97 mg/mL. [ABSTRACT FROM AUTHOR]

Bioremediation uses microorganisms to detoxify or remove pollution. This paper reports a study to evaluate the efficacy of removing hexavalent chromium (Cr(VI)) using a metal-resistant bacterium. Molecular identification reveals it to be Staphylococcus gallinarum strain VIII1. This can reduce 100 mg/L of Cr(VI) after 72 h at pH 7 and 30°C. Abatement rate is increased in the presence of glucose, glycerol and copper ions. Immobilised cells in sodium alginate beads showed a high reduction efficiency compared to free cells. Bioreduction by resting and permeabilized cells confirms that this strain removes chromate ions by an enzymatic process. [ABSTRACT FROM AUTHOR]

The aim of this study was the determination of the chemical compounds of Lavandula stoechas essential oil from Aknol (LSEOA), Khenifra (LSEOK), and Beni Mellal (LSEOB), and the in vitro investigation of their antibacterial, anticandidal, and antioxidant effects, and in silico anti-SARS-CoV-2 activity. The chemical profile of LSEO was determined using GC-MS-MS analysis, the results of which showed a qualitative and quantitative variation in the chemical composition of volatile compounds including L-fenchone, cubebol, camphor, bornyl acetate, and τ-muurolol; indicating that the biosynthesis of essential oils of Lavandula stoechas (LSEO) varied depending on the site of growth. The antioxidant activity was evaluated using the ABTS and FRAP methods, our results showed that this tested oil is endowed with an ABTS inhibitory effect and an important reducing power which varies between 4.82 ± 1.52 and 15.73 ± 3.26 mg EAA/g extract. The results of antibacterial activity of LSEOA, LSEOK and LSEOB, tested against Gram-positive and Gram-negative bacteria, revealed that B. subtilis (20.66 ± 1.15–25 ± 4.35 mm), P. mirabilis (18.66 ± 1.15–18.66 ± 1.15 mm), and P. aeruginosa (13.33 ± 1.15–19 ± 1.00 mm) are the most susceptible strains to LSEOA, LSEOK and LSEOB of which LSEOB exhibits bactericidal effect against P. mirabilis. furthermore The LSEO exhibited varying degrees of anticandidal activity with an inhibition zones of 25.33 ± 0.5, 22.66 ± 2.51, and 19 ± 1 mm for LSEOK, LSEOB, and LSEOA, respectively. Additionally, the in silico molecular docking process, performed using Chimera Vina and Surflex-Dock programs, indicated that LSEO could inhibit SARS-CoV-2. These important biological properties of LSEO qualify this plant as an interesting source of natural bioactive compounds with medicinal actions. [ABSTRACT FROM AUTHOR]

Addressing infectious diseases poses a significant healthcare challenge due to the growing resistance of microorganisms to antibiotics. Consequently, extensive research efforts have been dedicated to identifying alternative molecules to antibiotics that can combat these infectious diseases. Notably, a wealth of bioactive compounds has been discovered in medicinal and aromatic plants, and their potential utility in the development of treatments for infectious diseases has been well-established. In this study, we employed two extraction methods, namely maceration and ultrasound-assisted extraction (UAE), and four different solvents with varying polarities to isolate bioactive compounds from Cistus ladanifer L. Subsequently, quantification of polyphenols was determined in all the extracted samples. Following this, we conducted both qualitative and quantitative assessments of the antibacterial activity of these extracts. Moreover, we delved into the mechanism of action of the most potent extract using scanning electron microscopy. The results revealed that methanol was the best solvent for extracting bioactive molecules and that UAE had a high extraction efficiency since it gave a higher yield of total polyphenols than the one acquired by maceration. Regarding the results of the disk diffusion assay, the extracts that were prepared by UAE were more effective against our bacterial strains than those extracted by maceration. Electron micrographs of damaged cells revealed that the methanolic extract obtained by UAE affected the integrity of the cell membrane. These outcomes have underscored the presence of active compounds within Cistus ladanifer L. that could serve as potential alternatives to antibiotics against some of the most pathogenic bacterial species. [ABSTRACT FROM AUTHOR]