1,720,975 research outputs found
Potential of fungi as category I Consolidated BioProcessing organisms for cellulosic ethanol production
No full textConsolidated BioProcessing (CBP) can provide an important contribution to reducing ethanol production
costs and moving from cellulosic feedstock to fuel ethanol tanks. Several efforts have so far been focused
mainly on CBP category II engineering an ethanologen yeast or bacterium to be cellulolytic, but the limited
ability of the category II CBP system for producing enzymes for lignocellulose degradation remains a
challenge. As an alternative, category I CBP, aimed at engineering a cellulase producer to be ethanologenic,
could be pursued, but it is still in its infancy. Some cellulolytic thermophilic bacteria have been described
as potential candidates for category I CBP. However, only fungi naturally produce the needed titers of
cellulases required for the complete saccharification of pretreated lignocellulose. In this review, potential
of cellulolytic fungi as candidates for category I CBP is discussed
Last Advances in Synthesis of Added Value Compounds and Materials by LaccasemediatedBiocatalysis
No full textLaccases represent versatile catalysts being able to oxidize a wide range of aromatic substrates and are susceptible of several
industrial applications based on both oxidative degradation reactions and synthetic chemistry. The range of laccase based synthetic reactions
is extremely wide. Laccases are able to catalyze transformation of antibiotics based on both -lactams functionalization and
phtalides functionalization. These enzymes can also catalyze derivatization of amino acids to obtain metabolically stable amino acid analogues,
maximizing biological response while minimizing toxicity, thus representing an useful system for drug development. Biomolecules
having antioxidative and anticancer activity can also be produced by laccase-mediated reactions of flavonoids oxidative coupling
and phenoxazinones synthesis. Application of laccases to production of new derivatives of the hormones resveratrol, 17ß-estradiol,
totarol and isoeugenol and oligomerization products of substituted imidazoles was also reported, with applications for pharmacological
purposes due to hormonal activity of the products. The enzymatic preparation of aromatic polymeric materials by the action of laccases
represents a viable and non-toxic alternative to the usual formaldehyde-based chemical production of these compounds and it has been
reported for several substrates such as 2,6-dimethylphenol, 4-hydroxybenzoic acid derivatives, 3,5-dimethoxy-4-hydroxybenzoic acid and
3,5-dimethyl-4-hydroxybenzoic acid, aniline and acrylamide. Moreover, laccase-mediated biografting of phenols or certain other types of
low-molecular weight compounds provides a method for tailoring the surface of lignocellulosics or for adhesion enhancement in binderless
wood boards under mild conditions and usually without harmful solvents. Laccase-mediated modification of lignocellulosic materials
is accomplished through two main routes: coupling of low-molecular weight compounds onto lignocellulosic materials and laccase mediated
cross-linking of lignin molecules in situ. Depending on the choice of laccase substrate, properties such as improved strength properties,
increased antimicrobial resistance, or hydrophilicity/ hydrophobicity can be imparted to lignocellulosic materials
Metagenomics for the development of new biocatalysts to advance lignocellulose saccharification for bioeconomic development
No full textThe world economy is moving toward the use of renewable and nonedible lignocellulosic biomasses as substitutes for fossil sources in order to decrease the environmental impact of manufacturing processes and overcome the conflict with food production. Enzymatic hydrolysis of the feedstock is a key technology for bio-based chemical production, and the identification of novel, less expensive and more efficient biocatalysts is one of the main challenges. As the genomic era has shown that only a few microorganisms can be cultured under standard laboratory conditions, the extraction and analysis of genetic material directly from environmental samples, termed metagenomics, is a promising way to overcome this bottleneck. Two screening methodologies can be used on metagenomic material: the function-driven approach of expression libraries and sequence-driven analysis based on gene homology. Both techniques have been shown to be useful for the discovery of novel biocatalysts for lignocellulose conversion, and they enabled identification of several (hemi)cellulases and accessory enzymes involved in (hemi)cellulose hydrolysis. This review summarizes the latest progress in metagenomics aimed at discovering new enzymes for lignocellulose saccharification
Copper induction of enhanced green fluorescent protein expression in Pleurotus ostreatus driven by laccase poxa1b promoter.
No full textIn silico analyses of several laccase promoter sequences have shown the presence of many different responsive elements differentially distributed along the promoter sequences. Analysis of Pleurotus ostreatus laccase promoter poxa1b extending around 1400-bp upstream of the start codon showed the presence of several putative response elements, such as 10 metal-responsive elements. Development of a system for in vivo analysis of P. ostreatus laccase promoter poxa1b by enhanced green fluorescent protein expression was carried out, based on a polyethylene glycol-mediated procedure for fungal transformation. Quantitative measurement of fluorescence expressed in P. ostreatus transformants grown in the presence and in the absence of copper sulfate was performed, demonstrating an increase in expression level induced by the metal
Enhanced Green Fluorescent Protein Expression in Pleurotus ostreatus for In Vivo Analysis of Fungal Laccase Promoters.
No full textThe laccase family of Pleurotus ostreatus has been widely characterized, and studies of the genes coding for laccase isoenzymes in P. ostreatus have so far led to the identification of four different genes and the corresponding cDNAs, poxc, pox1, poxa1b and poxa3. Analyses of P. ostreatus laccase promoters poxc, pox1, poxa1b and poxa3 have allowed identification of several putative response elements, and sequences of metal-responsive elements involved in the formation of complexes with fungal proteins have been identified in poxc and poxa1b promoters. In this work, development of a system for in vivo analysis of P. ostreatus laccase promoter poxc by enhanced green fluorescent protein expression is performed, based on a poly ethylene glycol-mediated procedure for fungal transformation. A quantitative measurement of fluorescence expressed in P. ostreatus transformants is hereby reported for the first time for this fungus
Cellulolytic Bacillus strains from natural habitats - A review
No full textFossil fuel reserves depletion, global warming, costly and problematic waste recycling and population growth greatly induce to fi nd renewable energy sources. Second generation bioethanol produced from lignocellulosic materials exhibits great potential as liquid biofuel to substitute gasoline. Production costs of enzymes involved in cellulose hydrolysis into fermentable sugars represent the main obstacle to achieve competitive production of cellulosic ethanol. Cheaper and more effi cient biocatalysts for the saccharifi cation step are, therefore, required for making the whole process more competitive. The biodiversity of natural niches has been so far exploited for the isolation of new cellulolytic microorganisms whose enzymes are naturally evolved for an effi cient conversion of cellulose into fermentable sugars. This review discusses advances in isolation of bacteria, namely Bacillus spp., from several natural habitats and their ability to produce cellulase activity
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