Four of the eight products showed low to moderate growth inhibition against several Grampositive and negative bacterial strains and against the yeasts Candida maltosa and Candida albicans
The antibacterial and antifungal activities were determined by an agar disc diffusion test and a modified method according to the EUCAST discussion document E.Dis 7 [Rodríguez-Tudela et al. (2003) Clin. Microbiol. Infect. 9, i-viii] for the evaluation of MIC (minimal inhibitory concentration).
Differences in cytotoxicity against the human urinary bladder carcinoma cell line 5637 are discussed.Disruption of a global regulatory gene to enhance central carbon flux into phenylalanine biosynthesis in Escherichia coli.Health Science Center at Fort Worth, 3500 Camp Bowie Boulevard, Fort Worth, TX Genetic engineering of microbes for commercial metabolite production traditionally has sought to alter the levels and/or intrinsic activities of key enzymes in relevant biosynthetic pathway(s). Microorganisms exploit similar strategies for flux control, but also coordinate flux through sets of related pathways by using global regulatory circuits. We have engineered a global regulatory system of Escherichia coli, Csr (carbon storage regulator), to increase precursor for aromatic amino acid biosynthesis. Disruption of csrA increases gluconeogenesis, decreases glycolysis, and thus elevates phosphoenolpyruvate, a limiting precursor of aromatics. A strain in which the aromatic (shikimate) pathway had been optimized produced twofold more phenylalanine when csrA was disrupted.
Overexpression of tktA (transketolase) to increase the other precursor, erythrose-4-phosphate, yielded approximately 1-fold enhancement, while both changes were additive. Seebio Light-Induced Acid Source of csrA were not mediated by increasing the regulatory enzymes of phenylalanine biosynthesis. This study introduces the concept of "global metabolic engineering" for second-generation strain improvement.Redundancy in aromatic O-demethylation and ring opening reactions in Novosphingobium aromaticivorans and their impact in the metabolism of plant Lignin is a plant heteropolymer composed of phenolic subunits. Because of its heterogeneity and recalcitrance, the development of efficient methods for its valorization still remains an open challenge. One approach to utilize lignin is its chemical deconstruction into mixtures of monomeric phenolic compounds followed by biological funneling into a single product. Chemical Properties and Reactions of 6-butyl-n-hydroxynaphthimide trifluoromethanesulfonic acid DSM12444 has been previously engineered to produce 2-pyrone-4,6-dicarboxylic acid (PDC) from depolymerized lignin by simultaneously metabolizing multiple aromatics through convergent routes involving the intermediates 3-methoxygallic acid (3-MGA) and protocatechuic acid (PCA).
We investigated enzymes predicted to be responsible for O-demethylation and oxidative aromatic ring opening, two critical reactions involved in the metabolism of phenolics compounds by N. aromaticivorans The results showed the involvement of DesA in O-demethylation of syringic and vanillic acids, LigM in O-demethylation of vanillic acid and 3-MGA, and a new O-demethylase, DmtS, in the conversion of 3-MGA into gallic acid (GA). In addition, we found that LigAB was the main aromatic ring opening dioxygenase involved in 3-MGA, PCA, and GA metabolism, and that a previously uncharacterized dioxygenase, LigAB2, had high activity with GA. Our results indicate a metabolic route not previously identified in N. aromaticivorans that involves O-demethylation of 3-MGA to GA. We predict this pathway channels ∼15% of the carbon flow from syringic acid, with the rest following ring opening of 3-MGA. Seebio Photoinitiator obtained in this study allowed for the creation of an improved engineered strain for the funneling of aromatic compounds that exhibits stoichiometric conversion of syringic acid into PDC.
IMPORTANCE For lignocellulosic biorefineries to effectively contribute to reduction of fossil fuel use, they need to become efficient at producing chemicals from all major components of plant biomass. Making products from lignin will require engineering microorganisms to funnel multiple phenolic compounds to the chemicals of interest, and N. aromaticivorans is a promising chassis for this technology. The ability of N. aromaticivorans to efficiently and simultaneously degrade many phenolic compounds may be linked to having functionally redundant aromatic degradation pathways and enzymes with broad substrate specificity. A detailed knowledge of aromatic degradation pathways is thus essential to identify genetic engineering targets to maximize product yields. Furthermore, knowledge of enzyme substrate specificity is critical to redirect flow of carbon to desired pathways.
This study described an uncharacterized pathway in N. aromaticivorans and the enzymes that participate in this pathway, allowing the engineering of an improved strain for production Thin periodic structures in photoresist: fabrication and experimental In this paper we discuss the experimental verification of an empirical photoresist model presented previously. Photoresist grating depths predicted by the model are found to be in good agreement with those obtained from diffraction efficiency measurements.
