Direct Monitoring of Membrane Fatty Acid Changes and Effects on the Isoleucine/Valine Pathways in an ndgR Deletion Mutant of Streptomyces coelicolor.

NdgR, a global regulator in soil-dwelling and antibiotic-producing Streptomyces, is known to regulate branched-chain amino acid metabolism by binding to the upstream region of synthetic genes. However, its numerous and complex roles are not yet fully understood. To more fully reveal the function of NdgR, phospholipid fatty acid (PLFA) analysis with gas chromatography-mass spectrometry (GC-MS) was used to assess the effects of an ndgR deletion mutant of Streptomyces coelicolor. The deletion of ndgR was found to decrease the levels of isoleucine- and leucine-related fatty acids but increase those of valine-related fatty acids. Furthermore, the defects in leucine and isoleucine metabolism caused by the deletion impaired the growth of Streptomyces at low temperatures. Supplementation of leucine and isoleucine, however, could complement this defect under cold shock condition. NdgR was thus shown to be involved in the control of branched-chain amino acids and consequently affected the membrane fatty acid composition in Streptomyces. While isoleucine and valine could be synthesized by the same enzymes (IlvB/N, IlvC, IlvD, and IlvE), ndgR deletion did not affect them in the same way. This suggests that NdgR is involved in the upper isoleucine and valine pathways, or that its control over them differs in some respect.

Adsorptive removal of crude petroleum oil from water using floating pinewood biochar decorated with coconut oil-derived fatty acids.

The present investigation deals with the adsorptive removal of crude petroleum oil from the water surface using coconut oil-modified pinewood biochar. Biochar generated at higher pyrolysis temperature (700 °C) revealed higher fatty acid-binding efficiency responsible for the excellent hydrophobicity of the biochar. Fatty acids composition attached to the biochar produced at 700 °C was (mg g-1 BC) lauric acid (9.024), myristic acid (5.065), palmitic acid (2.769), capric acid (1.639), oleic acid (1.362), stearic acid (1.114), and linoleic acid (0.130). Simulation of the experimental adsorption data of pristine and modified pinewood biochar generated at 700 °C offered the best fit to pseudo-first-order kinetics (R2 > 0.97) and Langmuir isotherm model (R2 > 0.99) based on the highest regression coefficients. Consequently, the adsorption process was mainly driven by surface hydrophobic interactions including π-π electron-donor-acceptor between electron-rich (π-donor) polycyclic aromatic hydrocarbons from the crude oil and biochar (π-acceptor). A maximum adsorption capacity (Qmax) of 5.315 g g-1 was achieved by modified floating biochar within 60 min. Whereas the reusability testing revealed 49.39% and 51.40% was the adsorption efficiency of pristine and modified biochar at the fifth adsorption-desorption cycle.

Conversion of waste cooking oil into biodiesel using heterogenous catalyst derived from cork biochar.

In this study, a heterogeneous catalyst prepared by pyrolysis of waste cork (Quercus suber) was used for the transesterification of waste cooking oil (WCO). Physicochemical properties of the synthesized biochar catalyst were studied using BET, SEM, FTIR, and XRD. The experiment results demonstrate that heterogeneous catalyst synthesized at 600 °C showed maximum fatty acids methyl esters (FAMEs) conversion (98%) at alcohol:oil (25:1), catalyst loading (1.5% w/v) and temperature 65 °C. Biodiesel produced from WCO (Canola oil) mainly composed of FAMEs in following order C18:1 > C18:2 > C16:0 > C18:0 > C20:0. Properties of produced biodiesel were analysed as cetane number (CN) 50.56, higher heating value (HHV) 39.5, kinematic viscosity (ʋ) 3.9, and density (ρ) 0.87.

Discarded Egg Yolk as an Alternate Source of Poly(3-Hydroxybutyrate-co-3-hydroxyhexanoate).

Many poultry eggs are discarded worldwide because of infection (i.e., avian flu) or presence of high levels of pesticides. The possibility of adopting egg yolk as a source material to produce polyhydroxyalkanoate (PHA) biopolymer was examined in this study. Cupriavidus necator Re2133/pCB81 was used for the production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3HHx), a polymer that would normally require long-chain fatty acids as carbon feedstocks for the incorporation of 3HHx monomers. The optimal medium contained 5% egg yolk oil and ammonium nitrate as a nitrogen source, with a carbon/nitrogen (C/N) ratio of 20. Time course monitoring using the optimized medium was conducted for 5 days. Biomass production was 13.1 g/l, with 43.7% co-polymer content. Comparison with other studies using plant oils and the current study using egg yolk oil revealed similar polymer yields. Thus, discarded egg yolks could be a potential source of PHA.

Enhanced production of glutaric acid by NADH oxidase and GabD-reinforced bioconversion from l-lysine.

Glutaric acid is a promising alternative chemical to phthalate plasticizer since it can be produced by the bioconversion of lysine. Though, recent studies have enabled the high-yield production of its precursor, 5-aminovaleric acid (AMV), glutaric acid production via the AMV pathway has been limited by the need for cofactors. Introduction of NAD(P)H oxidase (Nox) with GabTD enzyme remarkably diminished the demand for oxidized nicotinamide adenine dinucleotide (NAD+ ). Supply of oxygen through vigorous shaking had a significant effect on the conversion of AMV with a reduced requirement of NAD + . A high conversion rate was achieved in Nox coupled GabTD reaction under optimized expression vector, terrific broth (TB), and pH 8.5 at high cell density. Supplementary expression of GabD resulted in the production of 353 ± 35 mM glutaric acid with 88.3 ± 8.7% conversion from 400 mM AMV. Moreover, the reaction with a higher concentration of AMV could produce 528 ± 21 mM glutaric acid with 66.0 ± 2.7% conversion. In addition, the co-biotransformation strategy of GabTD and DavBA whole cells could produce 282 mM glutaric acid with 70.8% conversion from lysine, compared to the 111 mM glutaric acid yield from the combined GabTD-DavBA system.