Biodegradation of ciprofloxacin using machine learning tools: Kinetics and modelling.

Recently, the rampant administration of antibiotics and their synthetic organic constitutes have exacerbated adverse effects on ecosystems, affecting the health of animals, plants, and humans by promoting the emergence of extreme multidrug-resistant bacteria (XDR), antibiotic resistance bacterial variants (ARB), and genes (ARGs). The constraints, such as high costs, by-product formation, etc., associated with the physico-chemical treatment process limit their efficacy in achieving efficient wastewater remediation. Biodegradation is a cost-effective, energy-saving, sustainable alternative for removing emerging organic pollutants from environmental matrices. In view of the same, the current study aims to explore the biodegradation of ciprofloxacin using microbial consortia via metabolic pathways. The optimal parameters for biodegradation were assessed by employing machine learning tools, viz. Artificial Neural Network (ANN) and statistical optimization tool (Response Surface Methodology, RSM) using the Box-Behnken design (BBD). Under optimal culture conditions, the designed bacterial consortia degraded ciprofloxacin with 95.5% efficiency, aligning with model prediction results, i.e., 95.20% (RSM) and 94.53% (ANN), respectively. Thus, befitting amendments to the biodegradation process can augment efficiency and lead to a greener solution for antibiotic degradation from aqueous media.

Biodegradation of emerging organic pollutant gemfibrozil: Mechanism, kinetics and pathway modelling.

The increasing population has raised the demand for pharmaceutical and personal care products to maintain a good health. Gemfibrozil (GEM), is extensively used as a lipid regulator and is frequently detected in wastewater treatment systems and poses deleterious health and ecological effects. Hence, the current study employing Bacillus sp. N2 reports the degradation of gemfibrozil via co-metabolism in 15 days. The study reported 86 % degradation with GEM (20 mgL-1) using sucrose (150 mgL-1) as a co-substrate; as compared to 42 % without a co-substrate. Further, time-profiling studies of metabolites revealed significant demethylation and decarboxylation reactions during degradation that leads to formation of six (M1, M2, M3, M4, M5, M6) metabolites as by-products. Based on the LC-MS analysis a potential degradation pathway for GEM by Bacillus sp. N2 was proposed. The degradation of GEM has not been reported so far and the study envisages eco-friendly approach to tackle pharmaceutical- active- compounds.

The bandgap of sulfur-doped Ag2O nanoparticles.

A narrow band gap restricts photocatalytic applications of Ag2O nanoparticles, but appropriate doping can favorably modify this aspect. Given this, density functional theory (DFT) calculations were conducted, revealing that substitutional sulfur doping of Ag2O could increase its bandgap and stabilize oxygen vacancies. A hydrothermal precipitation protocol was employed to prepare sulfur-doped (S-doped) Ag2O nanoparticles. The band gap of the prepared nanoparticles increased to 1.89 eV with 1.25-mole percent S-doping. XPS analysis of the samples also revealed that S-doping increased oxygen vacancies in the prepared Ag2O nanoparticles. Furthermore, S-doping caused a major shift in the valence band position to a negative value. These doped Ag2O nanoparticles showed an enhanced visible-light photocatalytic activity towards rhodamine B (RhB) degradation.

Degradation of ß-lactam antibiotic ampicillin using sustainable microbial peroxide producing cell system.

The enormous use of synthetic antibiotic and personal care products has impacted the natural microbiome and ecosystem. Overtime, treatment technologies developed suffered due to incomplete removal hence, a pilot dual-chambered microbial peroxide-producing cell that degrades ampicillin catalyzed by homogenous Fenton-reaction was designed. The system reported maximum current at 16.714 ± 0.048 µAcm-2, power output of 1.956 ± 0.015 mW m-2; 88 ± 2.90 mM of H2O2 generation with Na2SO4 that degraded 95.9 ± 3.00 to 97.8 ± 3.20% of 10 mg L-1ampicillin within 72 hrs with electro-active Shewanella putrefaciens. An E. coli bioactivity assay with ampicillin exhibited no sensitivity zone due to the loss of activity. Analytical spectroscopic studies reveal ß-Lactam ring deformation; Liquid Chromatography-Mass Spectroscopy clearly shows the presence of degradation metabolites. A sustainable wastewater treatment with 72 ± 4.5% reduction in anodic chemical oxygen demand was achieved. Present results designate the technology, as promising for effective antibiotics removal for wastewater treatment concomitant with electricity generation.

One Substrate, Two Modes of C-H Functionalization: A Metal-Controlled Site-Selectivity Switch in C-H Arylation Reactions.

A unique site-selectivity switch has been achieved in the ruthenium-catalyzed C-H arylation reaction of N-acetyl-1,2-dihydroisoquinolines. This metal-mediated switch is antipodal to the previous report on the palladium-mediated C-4 C-H arylation on the same substrate. Mechanistic details reveal interesting aspects of the reaction pathway, and kinetic studies bring out the difference in the modes of C-H activation adopted by the two catalytic systems.

Ruthenium-catalyzed heteroatom-directed regioselective C-H arylation of indoles using a removable tether.

A new approach to C-2 arylated indoles has been developed by utilizing a ruthenium-catalyzed, heteroatom-directed regioselective C-H arylation. The reaction is highly site-selective and results in very good yields. The highlight of the work is the use of a removable directing group and compatibility of the catalytic system with halogen functional groups in the substrates.