Antimicrobial and antioxidant activities of lignin from residue of corn stover to ethanol production (original) (raw)
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Applied Biochemistry and Biotechnology, 2017
Lignin accounts for 15-35% of dry biomass materials. Therefore, developing valueadded co-products from lignin residues is increasingly important to improve the economic viability of biofuel production from biomass resources. The main objective of this work was to study the lignin extracts from corn stover residue obtained from a new and improved process for bioethanol production. Extraction conditions that favored high lignin yield were optimized, and antioxidant and antimicrobial activities of the resulting lignin were investigated. Potential estrogenic toxicity of lignin extracts was also evaluated. The corn stover was pretreated by low-moisture anhydrous ammonia (LMAA) and then subjected to enzymatic hydrolysis using cellulase and hemicellulase. The residues were then added with sodium hydroxide and extracted for different temperatures and times for enhancing lignin yield and the bioactivities. The optimal extraction conditions using 4% (w/v) sodium hydroxide were determined to be 50°C, 120 min, and 1:8 (w:v), the ratio between corn stover solids and extracting liquid. Under the optimal condition, 33.92 g of lignin yield per 100 g of corn stover residue was obtained.
Converting lignin to value-added products at high yields provides an avenue for making ethanol biorefineries more profitable while reducing the carbon footprint of products generally derived from petroleum. In this study, corn stover lignin was depolymerized by catalytic transfer hydrogenolysis (CTH) in supercritical ethanol with a Ru/C catalyst. The lignin-derived bio-oil was then sequentially extracted utilizing hexane, petroleum ether, chloroform, and ethyl acetate as solvents in order of less polar to polar, and the subsequent bio-oils were characterized using GPC, GC/MS, and HSQC NMR. Results show that the monomers in the bio-oil fractions contained primarily alkylated phenols, hydrogenated hydroxycinnamic acid derivatives, syringol and guaiacoltype lignins created from reductive cleavages of ether linkages, which were sequentially extracted into groups depending on the solvent polarity. The antimicrobial properties of the bio-oils were screened against Gram-positive (Bacillus subtilis, Lactobacillus amylovorus, and Staphylococcus epidermidis) and Gram-negative (Escherichia coli) bacteria and yeast (Saccharomyces cerevisiae) by examining microbial growth inhibition. Results show that CTH-derived bio-oils inhibited all tested organisms at concentrations less than 3 mg/mL. Total monomer concentration and the presence of specific monomers (i.e., syringyl propane) showed correlations to antimicrobial activity, likely due to cell death or membrane damage. This study provides insights into using sequential extraction to fractionate lignin-derived compounds and correlations between the properties of the extracted compounds and their antimicrobial activity.
Bioprospecting Antimicrobial Potential of Lignin Stream of Paddy Straw Against Food-Borne Pathogens
2020
The present study was carried out to exploit the antimicrobial potential of lignin extracts obtained from four varieties of paddy straw i.e. PUSA-44, PR-111, PR-114, PR-122 against Aeromonas hydrophila (MTCC 1739), Klebsiella pneumoniae (MTCC 7028), Escherichia coli (MTCC 739) and Staphylococcus aureus (MTCC 96). Antimicrobial activity was tested both qualitatively w.r.t. zone of inhibition (ZOI) and quantitatively w.r.t. minimum inhibitory concentration (MIC). The best results were shown by lignin obtained from PR-122, where ZOI (mm) and MIC (μg/ml) for A. hydrophila, K. pneumoniae, E. coli and S. aureus were found to be 25 and 50, 19.3 and 50, 20 and 100, 18.6 and 100, respectively. Further, the lignin extracts were characterized using FT-IR spectrum and zeta potential. The present study exploits the immense potential of valorization of lignin-stream obtained from paddy straw in food and pharma industries.
Characterization of Lignins Isolated from Industrial Residues and their Beneficial Uses
BioResources, 2016
The physico-chemical properties of lignin isolated from lignocellulosic bioethanol residues and hardwood kraft black liquor were compared with two commercial lignins, kraft softwood lignin, and soda non-wood lignin. Lignin from the industrial residues was isolated through the acid precipitation method. The amount of lignin isolated was approximately 38% of the dry weight of lignocellulosic bioethanol residues and approximately 27% of the black liquor solids. The numbers of methoxyl groups and phenolic and aliphatic hydroxyls were determined to derive a molecular formula for each of the four lignins. The molecular weights of the lignins were measured by high performance size exclusion chromatography. Potential value-added applications of the lignins were summarized based on their molecular weights and physico-chemical characteristics.
Lignocellulosic Biomass as Source for Lignin-Based Environmentally Benign Antioxidants
Molecules
Antioxidant activity is an essential aspect of oxygen-sensitive merchandise and goods, such as food and corresponding packaging, cosmetics, and biomedicine. Technical lignin has not yet been applied as a natural antioxidant, mainly due to the complex heterogeneous structure and polydispersity of lignin. This report presents antioxidant capacity studies completed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The influence of purification on lignin structure and activity was investigated. The purification procedure showed that double-fold selective extraction is the most efficient (confirmed by ultraviolet-visible (UV/Vis), Fourier transform infrared (FTIR), heteronuclear single quantum coherence (HSQC) and 31P nuclear magnetic resonance spectroscopy, size exclusion chromatography, and X-ray diffraction), resulting in fractions of very narrow polydispersity (3.2–1.6), up to four distinct absorption bands in UV/Vis spectroscopy. Due to differential scanning calorimetry measurem...
Polymers
The antiradical and antimicrobial activity of lignin and lignin-based films are both of great interest for applications such as food packaging additives. The polyphenolic structure of lignin in addition to the presence of O-containing functional groups is potentially responsible for these activities. This study used DPPH assays to discuss the antiradical activity of HPMC/lignin and HPMC/lignin/chitosan films. The scavenging activity (SA) of both binary (HPMC/lignin) and ternary (HPMC/lignin/chitosan) systems was affected by the percentage of the added lignin: the 5% addition showed the highest activity and the 30% addition had the lowest. Both scavenging activity and antimicrobial activity are dependent on the biomass source showing the following trend: organosolv of softwood > kraft of softwood > organosolv of grass. Testing the antimicrobial activities of lignins and lignin-containing films showed high antimicrobial activities against Gram-positive and Gram-negative bacteria...
Industrial Crops and Products, 2016
The lignin is the most important renewable source of aromatic compounds on earth. It could represent up to 40% of dry matter in a biomass, however, its potential is underestimated being used as heat recovery source in industrial processes. Therefore, this work aimed to show the chemical feature of lignin isolated from sequential acid-alkaline pretreatment of oil palm empty fruit bunches. The extracted lignin was subjected to studies of this thermal behavior and biological properties as antioxidant, antimicrobial, and antidiabetic. The 2D HSQC spectroscopy analysis showed syringyl aromatic structure and presence of aromatic rings in lignin. The antioxidant assay showed that 2 mg of lignin were required to inhibit 50 wt.% DPPH, while the antimicrobial test inhibited the growth of Escherichia coli, Salmonella enterica serovar thyphimurium, Bacillus subtilis and Staphyloccocus aureus. The antidiabetic assay revealed inhibition of 20% of ␣-amylase activity. The thermogravimetric analysis gave out two peaks of decomposition at 230 • C and 350 • C and the glass transition temperature at 70 • C. These results showed the potential of lignin as precursor of chemicals of added value in a biorefinery process using as feedstock oil palm empty fruit bunches.
Extraction and Characterization of Lignin from Different Biomass Resources
Lignocellulosic biomass has been acknowledged for potential use to produce chemicals and biomaterials. Lignin is the second most abundant natural polymer with cellulose being number one, making up to 10–25% of lignocellulosic biomass. Lignin is a three-dimensional, highly cross-linked macromolecule composed of three types of substituted phenols, which include: coniferyl, sinapyl, and p-coumaryl alcohols by enzymatic polymerization, yielding a vast number of functional groups and linkages. There is a wide range of lignin sources available, including: jute, hemp, cotton, and wood pulp. Hence, the lignin’s physical and chemical behavior will be different with respect to the original source and extraction method used. The objective of this research is to extract lignin from nonwood cellulosic biomass (Wheat straw, Pine straw, Alfalfa, Kenaf, and Flax fiber) by formic acid treatment followed by peroxyformic acid treatment for the potential use as a partial replacement for the phenol precursor in resole phenolic systems. Isolated lignins were purified to remove impurities and characterized by Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA) and Differential scanning calorimetry (DSC) analysis to compare thermal properties and chemical composition. It was found that lignin obtained from alfalfa provided the greatest yield of the various sources. Enthalpy measurements were higher for lignin from flax fiber and alfalfa at 190.57 and 160.90 J/g, respectively. The source of lignin samples was seen to affect the thermal properties. Overall, lignin extracted from wheat straw had the greatest thermal stability followed very closely by that obtained from flax fiber.