Combining in silico and in vitro approaches to understand the involvement of methylerythritol 4-phosphate and shikimate pathways in Agrobacterium tumefaciens for enhanced coenzyme Q10 production.

AIMS: To perform an integrated comparative analysis of metabolic pathway to understand coenzyme Q10 (CoQ10) production in Agrobacterium tumefaciens. METHODS AND RESULTS: Comparative analysis of the CoQ10 metabolic pathway in 10 organisms using a genome to KEGG orthology program (G2KO) and the KEGG database elucidated the completeness of the production pathway in A. tumefaciens. The specific roles of the key precursors and the enzymes in the metabolic network were subsequently confirmed using pathway inhibitors and enhancers. While the use of fosmidomycin and glyphosate was found to inhibit CoQ10 production by 54.54% to 99%, the supplementation of polyprenyl pyrophosphate of the methylerythritol 4-phosphate pathway and 4-hydroxybenzoate precursor of the shikimate pathway did increse the production of CoQ10 by 2.3-fold. CONCLUSIONS: The present study provides a comprehensive understanding of the CoQ10 biosynthetic pathway in A. tumefaciens, which would assist rational metabolic engineering strategies for augmenting CoQ10 biosynthesis.

Photocatalytic degradation of four emerging antibiotic contaminants and toxicity assessment in wastewater: A comprehensive study.

Excessive usage and unrestricted discharge of antibiotics in the environment lead to their accumulation in the ecosystem due to their highly stable and non-biodegradation nature. Photodegradation of four most consumed antibiotics such as amoxicillin, azithromycin, cefixime, and ciprofloxacin were studied using Cu2O-TiO2 nanotubes. Cytotoxicity evaluation of the native and transformed products was conducted on the RAW 264.7 cell lines. Photocatalyst loading (0.1-2.0 g/L), pH (5, 7 and 9), initial antibiotic load (50-1000 µg/mL) and cuprous oxide percentage (5, 10 and 20) were optimized for efficient photodegradation of antibiotics. Quenching experiments to evaluate the mechanism of photodegradation with hydroxyl and superoxide radicals were found the most reactive species of the selected antibiotics. Complete degradation of selected antibiotics was achieved in 90 min with 1.5 g/L of 10% Cu2O-TiO2 nanotubes with initial antibiotic concentration (100 µg/mL) at neutral pH of water matrix. The photocatalyst showed high chemical stability and reusability up to five consecutive cycles. Zeta potential studies confirms the high stability and activity of 10% C-TAC (Cuprous oxide doped Titanium dioxide nanotubes for Applied Catalysis) in the tested pH conditions. Photoluminescence and Electrochemical Impedance Spectroscopy data speculates that 10% C-TAC photocatalyst have efficient photoexcitation in the visible light for photodegradation of antibiotics samples. Inhibitory concentration (IC50) interpretation from the toxicity analysis of native antibiotics concluded that ciprofloxacin was the most toxic antibiotic among the selected antibiotics. Cytotoxicity percentage of transformed products showed r: -0.985, p: 0.01 (negative correlation) with the degradation percentage revealing the efficient degradation of selected antibiotics with no toxic by-products.

Valorization of wastewater to recover value-added products: A comprehensive insight and perspective on different technologies.

In recent years, due to rapid globalization and urbanization, the demand for fuels, energy, water and nutrients has been continuously increasing. To meet the future need of the society, wastewater is a prominent and emerging source for resource recovery. It provides an opportunity to recover valuable resources in the form of energy, fertilizers, electricity, nutrients and other products. The aim of this review is to elaborate the scientific literature on the valorization of wastewater using wide range of treatment technologies and reduce the existing knowledge gap in the field of resource recovery and water reuse. Several versatile, resilient environmental techniques/technologies such as ion exchange, bioelectrochemical, adsorption, electrodialysis, solvent extraction, etc. are employed for the extraction of value-added products from waste matrices. Since the last two decades, valuable resources such as polyhydroxyalkanoate (PHA), matrix or polymers, cellulosic fibers, syngas, biodiesel, electricity, nitrogen, phosphorus, sulfur, enzymes and a wide range of platform chemicals have been recovered from wastewater. In this review, the aspects related to the persisting global water issues, the technologies used for the recovery of different products and/or by-products, economic sustainability of the technologies and the challenges encountered during the valorization of wastewater are discussed comprehensively.