The separation of selected lignin/humic substance (HS) degradation compounds by capillary electrochromatography (CEC) with a methacrylate‐based monolithic column and a conventional column packed with ...5 μm octadecyl silica (ODS) particles is presented. The effects of organic modifier concentration, pH of the mobile phase, ionic strength, applied voltage, and temperature on the separation were investigated to determine the optimal separation conditions. With the increase of pH in the mobile phase, some of analytes start to ionize and both chromatographic partition and electrophoresis can play roles in separation simultaneously. Accordingly, different selectivity from high‐performance liquid chromatography (HPLC) and capillary electrophoresis (CE) could be achieved. The performances of both kinds of columns were compared. The results showed that the peaks of compounds obtained on the former column were much wider than those on the latter one, although good separation efficiency of alkylbenzenes could be readily achieved; the most probable reasons for this behavior and method to solve this problem were briefly discussed. The CEC of a soil fulvic acid with a monolithic column produced partly resolved broad bands; by means of nuclear magnetic resonance (NMR) analysis a wide range of oxygen derived aromatic substitution patterns was found with prominent contributions from phenolic and carboxylic groups.
The quantity and quality of lignin phenols (Σ8, Λ, S/V, C/V and (Ad/Al)^sub v^) in the sediments of three small Lobelia lakes with neither inlets nor outlets were investigated and compared with ...palynological data and lithology of the profiles. The method of alkaline CuO oxidation was used. Substantial differences with respect to sedimentary lignin concentration and provenance recorded along the profiles and among the sites are in good agreement with pollen data describing the dominant type of vegetation and with indices of soil erosion in the lakes' catchments. This relation shows that the compositions of lignin degradation products in these lakes are closely related to the local environmental conditions. In all the lakes gymnosperm wood is the main source of lignin products; however, each lake is characterized by different S/V index values. Especially good correlations were obtained between pine pollen proportions in sediments and the S/V index. The correlation between the C/V and (Ad/Al)^sub v^ indices indicates a higher degradation of organic matter when non-woody tissue is more abundant. This pilot study illustrates the usefulness and potential for a wider application of lignin oxidation products in palaeoecological reconstructions. This kind of data would be of special importance when investigating local presence/absence of woody plants and the role of angiosperms/gymnosperms in local vegetation. Estimates of lignin biodegradation levels, as well as the data on diagenetic processes, may afford supplementary information on possible disturbances in sedimentation.PUBLICATION ABSTRACT
•LC retention of carboxylic phenolic compounds was improved by using acid additives.•Acetic acid yielded 2–4 times enhanced ESI-MS sensitivity for lignin oligomers.•Greater sensitivity of acetic acid ...led to a higher number of identified lignin.
Characterization of complex lignin degradation products by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) requires a high sensitivity, which can be improved by use of optimized mobile phase additive. In this study, chromatographic separation and ionization efficiency for LC-MS analysis of lignin oligomers and lignin-derived phenolic compounds were compared among six different mobile phase additives. We found that acetic acid exhibits analytical performance superior to the other mobile phase additives for characterization of lignin degradation products by LC-(−)-ESI-MS/MS. The retention of phenolic compounds (PCs) containing carboxylic group was improved by using acidic additives instead of their ammonium salts. The use of acetic acid as an LC mobile phase additive enhanced the ionization efficiency of PCs in (−)-ESI-MS about 2 to 4 times higher than the other additives. The improved MS sensitivity with acetic acid yielded a higher coverage of fragment ions in LC-MS/MS analysis, leading to identification of four additional synthetic G-type lignin oligomers (LOs) than ammonium acetate. A similar degree of sensitivity enhancement was also demonstrated for degradation products from rice straw lignin using acetic acid additive over the others. The increased chromatographic retention and enhanced sensitivity of PCs and LOs provided by the use of acetic acid as an LC-(−)-ESI-MS mobile phase additive will facilitate structural analysis of lignin degradation products without relying on additional instrumentation.
The rapid spread of COVID-19 resulted in the revision of the value of ultraviolet C (UVC) sterilization in working spaces. This study aimed at re-evaluating the anti-UVC activity of four groups of ...natural products against human melanoma COLO679 and human normal dermal fibroblast (HDFa) cells, based on chemotherapeutic index.
Various cell lines were exposed to UVC for 3 min in the presence of increasing concentrations of test compounds and viable cell numbers were determined with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The anti-UVC activity was quantified by the ratio of the 50% cytotoxic concentration (determined without irradiation) to the 50% effective concentration (which abolished by 50% the UVC-induced loss of viability). Apoptosis was quantified as the subG1 population proportion following cell-cycle analysis.
Among four groups of major natural products, six phenylpropanoids showed the highest anti-UVC activity, followed by the lignified products and alkaline products that contain lignin and its degradation products. On the other hand, tannins and flavonoids showed lower activity due to their higher cytotoxicity. UVC-sensitive COLO679 cells lack dectin-1 protein expression.
These data suggest the prominent anti-UVC activity of lignin degradation products, and the possible involvement of dectin-1 expression in UVC-sensitivity.
Bioconversion of plant biomass into biofuels and bio-products produces large amounts of lignin. The aromatic biopolymers need to be degraded before being converted into value-added bio-products. ...Microbes can be environment-friendly and efficiently degrade lignin. Compared to fungi, bacteria have some advantages in lignin degradation, including broad tolerance to pH, temperature, and oxygen and the toolkit for genetic manipulation.
Our previous study isolated a novel ligninolytic bacterial strain Erwinia billingiae QL-Z3. Under optimized conditions, its rate of lignin degradation was 25.24% at 1.5 g/L lignin as the sole carbon source. Whole genome sequencing revealed 4556 genes in the genome of QL-Z3. Among 4428 protein-coding genes are 139 CAZyme genes, including 54 glycoside hydrolase (GH) and 16 auxiliary activity (AA) genes. In addition, 74 genes encoding extracellular enzymes are potentially involved in lignin degradation. Real-time PCR quantification demonstrated that the expression of potential ligninolytic genes were significantly induced by lignin. 8 knock-out mutants and complementary strains were constructed. Disruption of the gene for ELAC_205 (laccase) as well as EDYP_48 (Dyp-type peroxidase), ESOD_1236 (superoxide dismutase), EDIO_858 (dioxygenase), EMON_3330 (monooxygenase), or EMCAT_3587 (manganese catalase) significantly reduced the lignin-degrading activity of QL-Z3 by 47-69%. Heterologously expressed and purified enzymes further confirmed their role in lignin degradation. Fourier transform infrared spectroscopy (FTIR) results indicated that the lignin structure was damaged, the benzene ring structure and groups of macromolecules were opened, and the chemical bond was broken under the action of six enzymes encoded by genes. The abundant enzymatic metabolic products by EDYP_48, ELAC_205 and ESOD_1236 were systematically analyzed via liquid chromatography-mass spectrometry (LC-MS) analysis, and then provide a speculative pathway for lignin biodegradation. Finally, The activities of ligninolytic enzymes from fermentation supernatant, namely, LiP, MnP and Lac were 367.50 U/L, 839.50 U/L, and 219.00 U/L by orthogonal optimization.
Our findings provide that QL-Z3 and its enzymes have the potential for industrial application and hold great promise for the bioconversion of lignin into bioproducts in lignin valorization.
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