BackgroundThe discovery of lignin as activator for the redox enzyme lytic polysaccharide monooxygenases (LPMOs) for the oxidation of cell-wall polysaccharides opens a new scenario for investigation of the interplay between different lignocellulose-degrading enzymes. The lignin-active enzymes in one hand, and the carbohydrate active in the other, are linked through a variety of electrons carrier molecules either derived from lignin or enzymatically transferred. Likewise, in nature, many lignocellulose-degrading organisms are expressing those enzymes simultaneously, and we wanted to test if a major commercial available lignin oxidase enzyme, i.e., laccase could benefit and synergize the activity of the LPMOs by depolymerizing the insoluble lignin.ResultsIn this work, two fungal laccases together with a mediator (ABTS) were used to isolate low-molecular-weight lignin from lignocellulosic biomass. The isolated lignins were used as electron donors for activation of LPMOs. A direct correlation between the low-molecular-weight lignin isolated with laccases and an increased activity of a cellulolytic cocktail containing LPMO was found when pure cellulose was hydrolyzed. We then tried to implement existing commercial cellulases cocktail with laccase enzymes, but under the conditions tested, the co-incubation of laccases with LPMOs showed a substrate competition towards oxygen inhibiting the LPMO. In addition, we found that laccase treatment may cause other modifications to pure cellulose, rendering the material more recalcitrant for enzymatic saccharification.ConclusionsLaccase-mediated system was able to depolymerize lignin from pre-treated and native sugarcane bagasse and wheat straw, and the released phenolic molecules were able to donate electrons to LPMO enzymes boosting the overall enzymatic hydrolysis of cellulose. Likewise, other poly-phenol oxidase, we might have just started showing possible pros or cons in applying several oxidase enzymes for a simultaneous degradation of cellulose and lignin, and we found that the competition towards oxygen and their different consumption rates must be taken into account for any possible co-application.Electronic supplementary materialThe online version of this article (10.1186/s13068-017-0985-8) contains supplementary material, which is available to authorized users.

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Ferulic acid is a phenolic acid widely distributed in the plant kingdom. It presents a wide range of potential therapeutic effects useful in the treatments of cancer, diabetes, lung and cardiovascular diseases, as well as hepatic, neuro and photoprotective effects and antimicrobial and anti-inflammatory activities. Overall, the pharmaceutical potential of ferulic acid can be attributed to its ability to scavenge free radicals. However, recent studies have revealed that ferulic acid presents pharmacological properties beyond those related to its antioxidant activity, such as the ability to competitively inhibit HMG-CoA reductase and activate glucokinase, contributing to reduce hypercholesterolemia and hyperglycemia, respectively. The present review addresses ferulic acid dietary sources, the pharmacokinetic profile, antioxidant action mechanisms and therapeutic effects in the treatment and prevention of various diseases, in order to provide a basis for understanding its mechanisms of action as well as its pharmaceutical potential.Uniterms: Ferulic acid/properties. Ferulic acid/antioxidant activity. Ferulic acid/dietary sources. Ferulic acid/therapeutic effects. Natural products. Pharmacognosy.O ácido ferúlico é um ácido fenólico amplamente distribuído no reino vegetal. Ele apresenta uma ampla gama de potenciais efeitos terapêuticos utéis no tratamento do câncer, diabetes, doenças pulmonares e cardiovasculares, bem como efeitos hepáticos, neuro e fotoprotetores, atividades antimicrobianas e antiinflamatórias. O potencial farmacêutico do ácido ferúlico pode ser atribuído à sua capacidade em sequestrar radicais livres. No entanto, estudos recentes revelaram que o ácido ferúlico apresenta propriedades farmacológicas, além da sua atividade antioxidante, como a capacidade de inibir competitivamente a HMG-CoA redutase e ativar a glucoquinase, contribuindo para reduzir a hipercolesterolemia e hiperglicemia, respectivamente. A presente revisão aborda as fontes dietéticas de ácido ferúlico, o perfil farmacocinético, os mecanismos de ação como antioxidante e efeitos terapêuticos no tratamento e prevenção de várias doenças, de modo a proporcionar uma base para a compreensão dos seus mecanismos de ação, bem como os seus potenciais farmacêuticos.Unitermos: Ácido ferúlico/propriedades. Ácido ferúlico/atividade antioxidante. Ácido ferúlico/fontes dietéticas. Ácido ferúlico/efeitos terapêuticos. Produtos naturais. Farmacognosia. INTRODUCTIONNatural antioxidants exhibit therapeutic potential for a variety of diseases such as cancer, diabetes, and cardiovascular and neurodegenerative diseases (Kayahara et al., 1999;Kim et al., 2003;Soobrattee et al., 2005) where free radicals play a key role in development (Prior et al., 1998). Recently there has been increased public and scientific interest in employing natural antioxidants instead of synthetic antioxidants, due to their potential adverse effects on health which may include carcinogenicity (Ito et al., 1983;Würtzen, 1990;Osawa et al., 1990).Antioxidants found in vegetables can ac...

BackgroundLignin is a heterogeneous polymer representing a renewable source of aromatic and phenolic bio-derived products for the chemical industry. However, the inherent structural complexity and recalcitrance of lignin makes its conversion into valuable chemicals a challenge. Natural microbial communities produce biocatalysts derived from a large number of microorganisms, including those considered unculturable, which operate synergistically to perform a variety of bioconversion processes. Thus, metagenomic approaches are a powerful tool to reveal novel optimized metabolic pathways for lignin conversion and valorization.ResultsThe lignin-degrading consortium (LigMet) was obtained from a sugarcane plantation soil sample. The LigMet taxonomical analyses (based on 16S rRNA) indicated prevalence of Proteobacteria, Actinobacteria and Firmicutes members, including the Alcaligenaceae and Micrococcaceae families, which were enriched in the LigMet compared to sugarcane soil. Analysis of global DNA sequencing revealed around 240,000 gene models, and 65 draft bacterial genomes were predicted. Along with depicting several peroxidases, dye-decolorizing peroxidases, laccases, carbohydrate esterases, and lignocellulosic auxiliary (redox) activities, the major pathways related to aromatic degradation were identified, including benzoate (or methylbenzoate) degradation to catechol (or methylcatechol), catechol ortho-cleavage, catechol meta-cleavage, and phthalate degradation. A novel Paenarthrobacter strain harboring eight gene clusters related to aromatic degradation was isolated from LigMet and was able to grow on lignin as major carbon source. Furthermore, a recombinant pathway for vanillin production was designed based on novel gene sequences coding for a feruloyl-CoA synthetase and an enoyl-CoA hydratase/aldolase retrieved from the metagenomic data set.ConclusionThe enrichment protocol described in the present study was successful for a microbial consortium establishment towards the lignin and aromatic metabolism, providing pathways and enzyme sets for synthetic biology engineering approaches. This work represents a pioneering study on lignin conversion and valorization strategies based on metagenomics, revealing several novel lignin conversion enzymes, aromatic-degrading bacterial genomes, and a novel bacterial strain of potential biotechnological interest. The validation of a biosynthetic route for vanillin synthesis confirmed the applicability of the targeted metagenome discovery approach for lignin valorization strategies.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1073-4) contains supplementary material, which is available to authorized users.

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