Component Of Lignin Research Articles

Phylogenetic and comparative genomics establishes origin of paralogy between homologs of AtMYB42 and AtMYB85 in last common ancestor of Brassicaceae via segmental duplication

Origin and evolution of secondary cell wall is considered key to colonization of terrestrial habitat by plants. The primary component of secondary cell wall, lignin, imparts strength and rigidity and enables plants to endure negative pressure created during transpiration. Members of the MYB transcription family, AtMYB42 and AtMYB85, play critical roles as regulators of lignin biosynthesis. Inspite of their functional significance, evolutionary history of homologs of AtMYB42 and AtMYB85 across land plants remains to be investigated. Our analysis revealed that homologs of AtMYB42 and AtMYB85 as two distinct genes are not present in any plant lineage outside Brassicaceae and only the ancestral form exists as AtMYB42/AtMYB85. Analysis of homologs of AtMYB42 and AtMYB85 across green plants combined with comparative genomics, selection pressure, and character-state reconstruction reveals that AtMYB42 and AtMYB85 are paralogous, and arose via segmental duplication, which may coincide with the α-event of WGD that occurred after the split of Brassicaceae-Caricaceae from the last common ancestor. Within Brassicaceae, homeologs and paralogs that arose as a result of polyploidization, and species- and lineage-specific changes could be observed. For instance, homologs of AtMYB42 were found to be deleted from the entire Brassica lineage. Analysis of homeologous segments in neopolyploids (B. napus, B. juncea, Camelina sativa), and meso-polyploid (B. rapa) revealed differential degrees of gene loss and retention. In Brassicaceae, homologs of AtMYB42 were found to be under purifying selection and of AtMYB85 under positive selection. High sequence identity in the coding region between homologs of AtMYB42 and AtMYB85 is indicative of redundant roles, and the loss of homologs of AtMYB42 in Brassica may be compensated by presence of AtMYB85 homologs and homeologs. The study thus forms the basis to investigate questions on regulatory diversification owing to variation in cis-elements between the paralogs and among homeologs, and, impact of differential selection pressure vis-a-vis redundant function.

Peroxyacetic Acid Pretreatment: A Potentially Promising Strategy towards Lignocellulose Biorefinery.

The stubborn and complex structure of lignocellulose hinders the valorization of each component of cellulose, hemicellulose, and lignin in the biorefinery industries. Therefore, efficient pretreatment is an essential and prerequisite step for lignocellulose biorefinery. Recently, a considerable number of studies have focused on peroxyacetic acid (PAA) pretreatment in lignocellulose fractionation and some breakthroughs have been achieved in recent decades. In this article, we aim to highlight the challenges of PAA pretreatment and propose a roadmap towards lignocellulose fractionation by PAA for future research. As a novel promising pretreatment method towards lignocellulosic fractionation, PAA is a strong oxidizing agent that can selectively remove lignin and hemicellulose from lignocellulose, retaining intact cellulose for downstream upgrading. PAA in lignocellulose pretreatment can be divided into commercial PAA, chemical activation PAA, and enzymatic in-situ generation of PAA. Each PAA for lignocellulose fractionation shows its own advantages and disadvantages. To meet the theme of green chemistry, enzymatic in-situ generation of PAA has aroused a great deal of enthusiasm in lignocellulose fractionation. Furthermore, mass balance and techno-economic analyses are discussed in order to evaluate the feasibility of PAA pretreatment in lignocellulose fractionation. Ultimately, some perspectives and opportunities are proposed to address the existing limitations in PAA pretreatment towards biomass biorefinery valorization. In summary, from the views of green chemistry, enzymatic in-situ generation of PAA will become a cutting-edge topic research in the lignocellulose fractionation in future.

Lignin-Based N-Doped Nanocarbons for the ORR

Fuel cells (FC) are one of the most viable energy conversion devices that could replace fossil-fuel based energy production in the future. As the oxygen reduction reaction (ORR) happening at the cathode side has slow kinetics, the usage of catalysts that speed up the process is inevitable. Most of the studied catalyst materials include precious metals or their alloys. Lately, the conversion of biomass to carbon nanomaterials and the usage of biomass-based carbons in different energy conversion systems has grown enormously [1].Lignin among the major components of lignocellulosic biomass, which is mainly produced in the pulp and paper industry or in biorefineries. To fully unlock the potential of biorefineries, the components of lignocellulosic biomass (e.g. lignin, hemicellulose, cellulose) must be fractionated and valorized [2]. Currently, lignin is used to produce electricity and heat in factories or landfilled. Since the main component of lignin is carbon, it is possible to synthesize lignin-based carbon nanomaterials.In this work, lignin from a local Estonian biorefinery was used to produce high specific surface area nanocarbons that were studied as catalysts for the ORR. Different ways (two-step or one-step) and temperatures (700 or 800 °C) were used to carry out the carbonization and activation processes. In the second step, dicyandiamide was used to carry out the nitrogen doping at 800 °C. Electrochemical characterization of the N-doped industrial lignin-based carbon catalysts were carried out by employing rotating disc electrode method. We show that a simultaneous carbonization and activation process in the presence of NaOH is the most effective towards creating the best catalyst precursor for the ORR, as the lignin-derived nanocarbon shows higher electrochemical activity towards the ORR than commercial N-doped graphene (Fig 1).

Engineering Pseudomonas putida for improved utilization of syringyl aromatics.

Lignin is a largely untapped source for the bioproduction of value‐added chemicals. Pseudomonas putida KT2440 has emerged as a strong candidate for bioprocessing of lignin feedstocks due to its resistance to several industrial solvents, broad metabolic capabilities, and genetic amenability. Here we demonstrate the engineering of P. putida for the ability to metabolize syringic acid, one of the major products that comes from the breakdown of the syringyl component of lignin. The rational design was first applied for the construction of strain Sy‐1 by overexpressing a native vanillate demethylase. Subsequent adaptive laboratory evolution (ALE) led to the generation of mutations that achieved robust growth on syringic acid as a sole carbon source. The best mutant showed a 30% increase in the growth rate over the original engineered strain. Genomic sequencing revealed multiple mutations repeated in separate evolved replicates. Reverse engineering of mutations identified in agmR, gbdR, fleQ, and the intergenic region of gstB and yadG into the parental strain recaptured the improved growth of the evolved strains to varied extent. These findings thus reveal the ability of P. putida to utilize lignin more fully as a feedstock and make it a more economically viable chassis for chemical production.

Features of the Chemical Composition and Structure of Birch Phloem Dioxane Lignin: A Comprehensive Study.

Understanding the chemical structure of lignin in the plant phloem contributes to the systematics of lignins of various biological origins, as well as the development of plant biomass valorization. In this study, the structure of the lignin from birch phloem has been characterized using the combination of three analytical techniques, including 2D NMR, Py-GC/MS, and APPI-Orbitrap-HRMS. Due to the specifics of the phloem chemical composition, two lignin preparations were analyzed: a sample obtained as dioxane lignin (DL) by the Pepper’s method and DL obtained after preliminary alkaline hydrolysis of the phloem. The obtained results demonstrated that birch phloem lignin possesses a guaiacyl–syringyl (G-S) nature with a unit ratio of (S/G) 0.7–0.9 and a higher degree of condensation compared to xylem lignin. It was indicated that its macromolecules are constructed from β-aryl ethers followed by phenylcoumaran and resinol structures as well as terminal groups in the form of cinnamic aldehyde and dihydroconiferyl alcohol. The presence of fatty acids and flavonoids removed during alkaline treatment was established. Tandem mass spectrometry made it possible to demonstrate that the polyphenolic components are impurities and are not incorporated into the structure of lignin macromolecules. An important component of phloem lignin is lignin–carbohydrate complexes incorporating xylopyranose moieties.

MICROBIAL PRODUCTION OF FERULIC ACID AND OPTIMIZATION OF THE MEDIUM PARAMETERS USING FRACTIONAL FACTORIAL DESIGN

Phenolics are widely distributed in plant kingdom and are therefore, an integral part of the diet, with significant amounts being reported in vegetables, fruits, and beverages. Various phenolic compounds have attracted the attention of food and medical scientists because of their fragrance, aroma, antioxidant, anti-inflammatory properties and ability to combat human diseases. Of these, Ferulic Acid (FA), a hydroxy cinnamic acid (related to trans-cinnamic acid), being natural, is of great demand in the food industry. As a component of lignin, FA is a precursor in the manufacture of other aromatic compounds. In our study, FA was produced using Lactobacillus spp. isolates and standard culture of Lactobacillus plantarum ATCC 8014. FA was extracted and partially characterized using Thin Layer Chromatography (TLC), Absorption maxima (λm) analysis and High Performance Liquid Chromatography (HPLC). Further, optimization of the fermentation medium was done using Factorial Fractional Design (FFD). Preliminary confirmation of the extracted FA was done using TLC, spectral analysis and purity assessed by HPLC. FA could be produced using Lactobacillus sp. and agro industrial waste viz., wheat bran, leading to a cost-effective protocol and product. Further, medium was optimized for the production of FA using FFD and it was observed that medium containing5.75% Wheat bran & 0.18% Tween 80 is optimum for the production of FA. The antimicrobial activity of FA was noteworthy against Aspergillus flavus and E. coli.

MICROBIAL PRODUCTION OF FERULIC ACID AND OPTIMIZATION OF THE MEDIUM PARAMETERS USING FRACTIONAL FACTORIAL DESIGN

Phenolics are widely distributed in plant kingdom and are therefore, an integral part of the diet, with significant amounts being reported in vegetables, fruits, and beverages. Various phenolic compounds have attracted the attention of food and medical scientists because of their fragrance, aroma, antioxidant, anti-inflammatory properties and ability to combat human diseases. Of these, Ferulic Acid (FA), a hydroxy cinnamic acid (related to trans-cinnamic acid), being natural, is of great demand in the food industry. As a component of lignin, FA is a precursor in the manufacture of other aromatic compounds. In our study, FA was produced using Lactobacillus spp. isolates and standard culture of Lactobacillus plantarum ATCC 8014. FA was extracted and partially characterized using Thin Layer Chromatography (TLC), Absorption maxima (λm) analysis and High Performance Liquid Chromatography (HPLC). Further, optimization of the fermentation medium was done using Factorial Fractional Design (FFD). Preliminary confirmation of the extracted FA was done using TLC, spectral analysis and purity assessed by HPLC. FA could be produced using Lactobacillus sp. and agro industrial waste viz., wheat bran, leading to a cost-effective protocol and product. Further, medium was optimized for the production of FA using FFD and it was observed that medium containing5.75% Wheat bran & 0.18% Tween 80 is optimum for the production of FA. The antimicrobial activity of FA was noteworthy against Aspergillus flavus and E. coli.

Mechanisms involved in thermal degradation of lignocellulosic fibers: a survey based on chemical composition

The aim of this study was to determine the Arrhenius parameters and degradation mechanism for each component of biomass, including extractives, water, hemicellulose, cellulose and lignin. A statistical tool (F-test) was used as well as simulations of the effects of each component and the respective chars formed during thermal degradation. Experimental and theoretical curves for each component were simultaneously fitted, and the influence on the final thermal degradation curve was evaluated. Simulation of the TG curve was based on recently published models, for which one, two and three-step mechanisms were tested to complete the statistical evaluation. The activation energy showed a dependence on the cellulose and the reaction order on the hemicellulose polymer structures. On the other hand, lignin is the most complex material in biomass and thus a broader range of degradation mechanisms is associated with its char and this plays a significant role in the final “tail” of the TG curve. In the case of cellulose and hemicellulose, autocatalysis is the most probable degradation mechanism while for the respective chars it is diffusion. The char formation significantly increases the activation energy. The results of this study provide an insight into the chemistry involved in the pyrolysis of multicomponent biomass, which will facilitate the building of a prediction model.

Genomic and proteomic analysis of lignin degrading and polyhydroxyalkanoate accumulating \u03b2-proteobacterium Pandoraea sp. ISTKB

BackgroundLignin is a major component of plant biomass and is recalcitrant to degradation due to its complex and heterogeneous aromatic structure. The biomass-based research mainly focuses on polysaccharides component of biomass and lignin is discarded as waste with very limited usage. The sustainability and success of plant polysaccharide-based biorefinery can be possible if lignin is utilized in improved ways and with minimal waste generation. Discovering new microbial strains and understanding their enzyme system for lignin degradation are necessary for its conversion into fuel and chemicals. The Pandoraea sp. ISTKB was previously characterized for lignin degradation and successfully applied for pretreatment of sugarcane bagasse and polyhydroxyalkanoate (PHA) production. In this study, genomic analysis and proteomics on aromatic polymer kraft lignin and vanillic acid are performed to find the important enzymes for polymer utilization.ResultsGenomic analysis of Pandoraea sp. ISTKB revealed the presence of strong lignin degradation machinery and identified various candidate genes responsible for lignin degradation and PHA production. We also applied label-free quantitative proteomic approach to identify the expression profile on monoaromatic compound vanillic acid (VA) and polyaromatic kraft lignin (KL). Genomic and proteomic analysis simultaneously discovered Dyp-type peroxidase, peroxidases, glycolate oxidase, aldehyde oxidase, GMC oxidoreductase, laccases, quinone oxidoreductase, dioxygenases, monooxygenases, glutathione-dependent etherases, dehydrogenases, reductases, and methyltransferases and various other recently reported enzyme systems such as superoxide dismutases or catalase–peroxidase for lignin degradation. A strong stress response and detoxification mechanism was discovered. The two important gene clusters for lignin degradation and three PHA polymerase spanning gene clusters were identified and all the clusters were functionally active on KL–VA.ConclusionsThe unusual aerobic ‘-CoA’-mediated degradation pathway of phenylacetate and benzoate (reported only in 16 and 4–5% of total sequenced bacterial genomes), peroxidase-accessory enzyme system, and fenton chemistry based are the major pathways observed for lignin degradation. Both ortho and meta ring cleavage pathways for aromatic compound degradation were observed in expression profile. Genomic and proteomic approaches provided validation to this strain’s robust machinery for the metabolism of recalcitrant compounds and PHA production and provide an opportunity to target important enzymes for lignin valorization in future.

Acute toxicity of emerging atmospheric pollutants from wood lignin due to biomass burning

Guaiacol (2-methoxyphenol) is an important atmospheric pollutant. It is the major component of wood lignin and is essentially emitted to the atmosphere during biomass burning. Its aging in the tropospheric aqueous phase leads to the generation of the following ring-retaining transformation products, also during nighttime: 4-nitroguaiacol, 6-nitroguaiacol, and dinitroguaiacol. This study presents the first toxicological data of guaiacol and its nitro derivatives and reveals their harmful potential for the ecosystem. Applying V. fischeri bioluminescence acute toxicity test, EC50 values range from 16.7 to 103mgL−1 after a 30-min incubation period, which classifies all investigated compounds as ‘harmful’ according to the European legislation. The investigation of environmentally relevant mixtures did not show significant joint actions between the four studied compounds. Therefore, their concentration addition can be considered for ecotoxicological purposes. However, a synergistic effect between guaiacol and a minor unidentified first-generation product of its aqueous-phase aging was observed and should be taken into account when assessing the reaction mixture toxicity. These results stress the need for further toxicological testing, including organisms of different trophic levels, to better evaluate the environmental hazard of guaiacol and especially its nitro derivatives.

31P NMR Characterization of Tricin and Its Structurally Similar Flavonoids

AbstractAbstract: Tricin, a flavonoid metabolite, has been recently identified as a component of lignin in select monocot plants. This finding has initiated consideration on updating the lignin biosynthesis pathway. We here report a rapid method of determination of tricin in corn stover lignin, based on 31P nuclear magnetic resonance (NMR) spectroscopy by phosphitylating with 2‐chloro‐4,4,5,5‐tetramethyl‐1,3,2‐dioxaphospholane (TMDP). Nine other flavonoids, with similar structure to tricin, have also been examined using the current method. The application of 31P NMR enables rapid identification of tricin‐like flavonoids in the heterogeneous lignin polymer. The well resolved spectroscopic peaks from these derivatized flavonoids and lignin functional groups provide important information for the determination of flavonoids individually or their association with lignin.

Development and validation of a sensitive UPLC-MS/MS instrumentation and alkaline nitrobenzene oxidation method for the determination of lignin monomers in wheat straw.

A method to determine the lignin monomers (p-hydroxybenzaldehyde, vanillin and syringaldehyde) in plant cell wall of wheat internode was developed and validated using a high-throughput nitrobenzene oxidation step and ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) for quantification. UPLC analyses were carried out using an reversed phase C18 column (ACQUITY UPLC BEH, 1.7μm, 2.1×100mm) and gradient elution with water and acetonitrile. This method was completely validated in terms of analyzing speed, linearity, sensitivity, limits of detection (LODs) and limits of quantification (LOQs).The three lignin monomers were successfully separated within 6min and only 2min were required to regain its equilibrium. The method linearity with regression coefficients values (R2) greater than 0.997. Additionally, LODs ranged from 0.21 to 0.89μgL-1 and LOQs ranged from 0.69 to 2.95μgL-1. The applicability of this analytical approach for determining the three lignin monomers was confirmed by the successful analysis of real samples of wheat stem internodes. The nitrobenzene oxidation method was used for the analysis of lignin monomers. We have optimized the treatment temperature (170°C, 1h) and realized the high-throughput using the microwave digestion instrument. Recovery of this extraction method ranged from 68.4% to 77.7%. The analysis result showed that the guaiacyl unit (G) was the major component of lignin and there was a higher content of the syringyl unit (S) than that of the hydroxybenzyl unit (H).

Manipulation of lignin metabolism by plant densities and its relationship with lodging resistance in wheat

Increasing plant density is one of the most efficient ways of increasing wheat (Triticum aestivum L.) grain production. However, overly dense plant populations have an increased risk of lodging. We examined lignin deposition during wheat stem development and the regulatory effects of plant density using the wheat cultivars shannong23 and weimai8. Plants were cultivated at densities of 75, 225 and 375 plants per m2 during two growing seasons. Our results showed that decreasing plant density enhanced culm quality, as revealed by increased culm diameter, wall thickness and dry weight per unit length, and improved the structure of sclerenchyma and vascular bundles by increasing lignification. In addition, more lignins were deposited in the secondary cell walls, resulting in strong lodging resistance. The guaiacyl unit was the major component of lignin and there was a higher content of the syringyl unit than that of the hydroxybenzyl unit. Furthermore, we hypothesised that the syringyl unit may correlate with stem stiffness. We describe here, to the best of our knowledge, the systematic study of the mechanism involved in the regulation of stem breaking strength by plant density, particularly the effect of plant density on lignin biosynthesis and its relationship with lodging resistance in wheat.

Good real world example of wood-based sustainable chemistry

One of the principles of Green chemistry is the usage of biomass instead of crude oil for the production of chemicals and chemical goods. Wood refers to the term biomass along with agricultural residues, energy crops, and the biogenic part of waste such as solid municipal waste, landfill, sewage gas and farming waste. Wood is mainly composed of cellulose, lignin and hemicelluloses. Cellulose is the main component of wood and lignin is the main by-product of cellulose extraction. Our green approach to both of these polymers resulted in creating a new process for hydrocellulose fiber production and a new sorbent for oil spills removal based on hydrolysis lignin. It is worth pointing out that our approach provides the use of two main wood components in the frame of “cradle to cradle” cycle (Fig. 1) that supports the circular economy concept for research and process development (Clark et al., 2016).

Single-Genotype Syntrophy by Rhodopseudomonas palustris Is Not a Strategy to Aid Redox Balance during Anaerobic Degradation of Lignin Monomers.

Rhodopseudomonas palustris has emerged as a model microbe for the anaerobic metabolism of p-coumarate, which is an aromatic compound and a primary component of lignin. However, under anaerobic conditions, R. palustris must actively eliminate excess reducing equivalents through a number of known strategies (e.g., CO2 fixation, H2 evolution) to avoid lethal redox imbalance. Others had hypothesized that to ease the burden of this redox imbalance, a clonal population of R. palustris could functionally differentiate into a pseudo-consortium. Within this pseudo-consortium, one sub-population would perform the aromatic moiety degradation into acetate, while the other sub-population would oxidize acetate, resulting in a single-genotype syntrophy through acetate sharing. Here, the objective was to test this hypothesis by utilizing microbial electrochemistry as a research tool with the extracellular-electron-transferring bacterium Geobacter sulfurreducens as a reporter strain replacing the hypothesized acetate-oxidizing sub-population. We used a 2 × 4 experimental design with pure cultures of R. palustris in serum bottles and co-cultures of R. palustris and G. sulfurreducens in bioelectrochemical systems. This experimental design included growth medium with and without bicarbonate to induce non-lethal and lethal redox imbalance conditions, respectively, in R. palustris. Finally, the design also included a mutant strain (NifA*) of R. palustris, which constitutively produces H2, to serve both as a positive control for metabolite secretion (H2) to G. sulfurreducens, and as a non-lethal redox control for without bicarbonate conditions. Our results demonstrate that acetate sharing between different sub-populations of R. palustris does not occur while degrading p-coumarate under either non-lethal or lethal redox imbalance conditions. This work highlights the strength of microbial electrochemistry as a tool for studying microbial syntrophy.

Lignin and lignans in plant defence: Insight from expression profiling of cinnamyl alcohol dehydrogenase genes during development and following fungal infection in Populus

Cinnamyl alcohol dehydrogenase (CAD) catalyses the final step in the biosynthesis of monolignol, the main component of lignin. Lignins, deposited in the secondary cell wall, play a role in plant defence against pathogens. We re-analysed the phylogeny of CAD/CAD-like genes using sequences from recently sequenced genomes, and analysed the temporal and spatial expression profiles of CAD/CAD-like genes in Populus trichocarpa healthy and infected plants. Three fungal pathogens (Rhizoctonia solani, Fusarium oxysporum, and Cytospora sp.), varying in lifestyle and pathogenicity, were used for plant infection. Phylogenetic analyses showed that CAD/CAD-like genes were distributed in classes represented by all members from angiosperm lineages including basal angiosperms and Selaginella. The analysed genes showed different expression profiles during development and demonstrated that three genes were involved in primary xylem maturation while five may function in secondary xylem formation. Expression analysis following inoculation with fungal pathogens, showed that five genes were induced in either stem or leaves. These results add further evidence that CAD/CAD-like genes have evolved specialised functions in plant development and defence against various pest and pathogens. Two genes (PoptrCAD11 and PoptrCAD15), which were induced under various stresses, could be treated as universal markers of plant defence using lignification or lignan biosynthesis.

Carbonate formation during lignin pyrolysis under CO2 and its effect on char oxidation

This work aims to study the transition of the chemical form of the alkali minerals during pyrolysis under a CO2 atmosphere, and its effect on char oxidation. Lignin containing a high concentration of Na was heated under a CO2 or Ar atmosphere, and the chemical form of Na in both chars was characterized using water extraction and capillary electrophoresis. These chars were subsequently gasified in air at various temperatures. Capillary electrophoresis analysis demonstrated that the organic-Na component of raw lignin was transformed into carbonate during pyrolysis under CO2. Almost all the Na in char formed under CO2 was a water-soluble carbonate, while water-insoluble Na was found only in char prepared under Ar. Water-insoluble Na was assumed to be R-COONa or –CNa in which Na was strongly bound with the char-matrix, making it resistant to water extraction. It was clearly shown that the chemical form of Na in lignin char was strongly dependent on the presence of CO2 during pyrolysis. Considering these experimental findings, a mechanism for transition of the chemical form of Na during pyrolysis under CO2 was proposed. In addition, significant differences between chars produced under CO2 and Ar appeared during gasification. The lowest temperature at which the oxidation of char formed under CO2 and Ar was 1073K and 923K, respectively. The major differences between chars prepared under Ar and CO2 were chemical form of sodium. The increase in oxidation temperature, therefore, was caused by transition of the chemical form of Na under CO2. In fact, –CNa, the most important catalyst in char oxidation, was not formed; although carbonate was formed during lignin pyrolysis under CO2. These results have important implications for the combustion or gasification of not only lignin but also Na ion-exchanged coal.

Effects of Alkali Treatment on Component and Structure and Enzyme Saccharifying Efficiency of Sweet Sorghum Bagasse

Sweet sorghum variety M81 was used as the experimental material, the sweet sorghum bagasse(SSB) was treated under four conditions(lime at room temperature, lime with microwave treatment, lime with autoclave treatment and sodium hydroxide at room temperature) with the washed and untreated SSB as control. The changes of lignocellulose structure and the cellulase saccharifying efficiency of SSB under different conditions were investigated. The results showed that four treatments effectively changed the lignocellulose component of sweet sorghum bagasse, especially in the case pretreated by sodium hydroxide under room temperature for two weeks, and lime played an important role in hemicellulose dissolution too. Scanning electron microscopy(SEM) observation indicated that the lignocellulose structure was different in two treatments of lime with autoclave treatment and sodium hydroxide at room temperature. The surface of lignin in the treatment of lime and autoclave was eroded seriously and its fragments adhered to the surface of cellulose, but the internal fiber structure still arranged tightly; in the treatment of NaOH at room temperature the lignocellulose beam structure was swelled and degraded, and the cellulose fiber net appeared due to the surface component of lignin removed a lot and many small holes appeared. By using the four pretreated methods, the cellulose and hemicellulose of sweet sorghum bagasse were enzymatically saccharified, the concentrations of glucose and xylose increased 1.5, 2.1, 1.9, 4.2 times and 3.1, 5.0, 4.9, 2.4 times, respectively as compared with the control. The direct conversion rate and the relative conversion rate of cellulose and hemicellulose are different, but have a significant guiding function for the choose of treatment methods and the effect of comprehensive evaluation, in addition, also an instructive function for the breeding and cultivating of sweet sorghum with high yield and good energy productive factors in the practical production.

A rapid colorimetric screening method for vanillic acid and vanillin-producing bacterial strains

To isolate a bacterial strain capable of biotransforming ferulic acid, a major component of lignin, into vanillin and vanillic acid by a rapid colorimetric screening method. For the production of vanillin, a natural aroma compound, we attempted to isolate a potential strain using a simple screening method based on pH change resulting from the degradation of ferulic acid. The strain Pseudomonas sp. AZ10 UPM exhibited a significant result because of colour changes observed on the assay plate on day 1 with a high intensity of yellow colour. The biotransformation of ferulic acid into vanillic acid by the AZ10 strain provided the yield (Yp/s ) and productivity (Pr ) of 1·08 mg mg(-1) and 53·1 mg L(-1) h(-1) , respectively. In fact, new investigations regarding lignin degradation revealed that the strain was not able to produce vanillin and vanillic acid directly from lignin; however, partially digested lignin by mixed enzymatic treatment allowed the strain to produce 30·7 mg l(-1) and 1·94 mg l(-1) of vanillic acid and biovanillin, respectively. (i) The rapid colorimetric screening method allowed the isolation of a biovanillin producer using ferulic acid as the sole carbon source. (ii) Enzymatic treatment partially digested lignin, which could then be utilized by the strain to produce biovanillin and vanillic acid. To the best of our knowledge, this is the first study reporting the use of a rapid colorimetric screening method for bacterial strains producing vanillin and vanillic acid from ferulic acid.

Biodegradation of ferulic acid by a newly isolated strain of Cupriavidus sp. B-8

As a major component of lignin and abundantly existing in softwood and hardwood, ferulic acid has been used as a lignin-related compound for lignin biodegradation study. Biodegradation of ferulic acid by Cupriavidus sp. B-8, a newly isolated strain, was studied. This strain is able to utilize a wide range of lignin-related aromatic compounds as the sole carbon and energy source, including guaiacol, veratric acid, vanillic acid, cinnamic acid, p-coumaric acid, ferulic acid, and sinapic acid. In addition, the effects of different concentrations of ferulic acid on growth of Cupriavidus sp. B-8 were studied. The growth of Cupriavidus sp. B-8 is better under the condition of lower concentration. High-performance liquid chromatography (HPLC) analysis reveals that above 95% of ferulic acid is degraded within 12 h by Cupriavidus sp. B-8. Based on identification of biodegradation intermediates and further metabolites, the biodegradation pathway of ferulic acid by Cupriavidus sp. B-8 was proposed. Ferulic acid is initially converted to 4-vinylguaiacol, and further oxidized to vanillic acid and protocatechuic acid.