Tracking the connection between evolutionary and functional shifts using the fungal lipase/feruloyl esterase A family

BACKGROUND: There have been many claims of adaptive molecular evolution, but what role does positive selection play in functional divergence? The aim of this study was to test the relationship between evolutionary and functional shifts with special emphasis on the role of the environment. For this purpose, we studied the fungal lipase/feruloyl esterase A family, whose functional diversification makes it a very promising candidate. RESULTS: The results suggested functional shift following a duplication event where neofunctionalisation of feruloyl esterase A had occurred with conservation of the ancestral lipase function. Evolutionary shift was detected using the branch-site model for testing positive selection on individual codons along specific lineages. Positively selected amino acids were detected. Furthermore, biological data obtained from site-directed mutagenesis experiments clearly demonstrated that certain amino acids under positive selection were involved in the functional shift. We reassessed evolutionary history in terms of environmental response, and hypothesized that environmental changes such as colonisation by terrestrial plants might have driven adaptation by functional diversification in Euascomycetes (Aspergilli), thus conferring a selective advantage on this group. CONCLUSION: The results reported here illustrate a rare example of connection between fundamental events in molecular evolution. We demonstrated an unequivocal connection between evolutionary and functional shifts, which led us to conclude that these events were probably linked to environmental change

A thermostable GH45 endoglucanase from yeast: impact of its atypical multimodularity on activity

BACKGROUND: The gene encoding an atypical multi-modular glycoside hydrolase family 45 endoglucanase bearing five different family 1 carbohydrate binding modules (CBM1), designated PpCel45A, was identified in the Pichia pastoris GS115 genome. RESULTS: PpCel45A (full-length open reading frame), and three derived constructs comprising (i) the catalytic module with its proximal CBM1, (ii) the catalytic module only, and (iii) the five CBM1 modules without catalytic module, were successfully expressed to high yields (up to 2 grams per litre of culture) in P. pastoris X33. Although the constructs containing the catalytic module displayed similar activities towards a range of glucans, comparison of their biochemical characteristics revealed striking differences. We observed a high thermostability of PpCel45A (Half life time of 6 h at 80°C), which decreased with the removal of CBMs and glycosylated linkers. However, both binding to crystalline cellulose and hydrolysis of crystalline cellulose and cellohexaose were substantially boosted by the presence of one CBM rather than five. CONCLUSIONS: The present study has revealed the specific features of the first characterized endo β-1,4 glucanase from yeast, whose thermostability is promising for biotechnological applications related to the saccharification of lignocellulosic biomass such as consolidated bioprocessing

High throughput screening of fungal enzymes of industrial interest

Biological Resource Centres (BRCs) and culture collections are essential components of the infrastructures for scientific research and industry and their establishment and maintenance depend on the implementation of reliable preservation techniques and appropriate quality assurance to allow them to become effective and efficient. Fungal strains identification and characterisation are important tasks within the context of BRC. Using a polyphasic approach for identification, allows the increment of associated information for every fungal strain. With this in mind and to harness the experimental based knowledge for scientific research on filamentous fungi, specifically the Nigri section of Aspergillus, the enzymatic activity of this fungal section was assessed by screening the activity of a set of enzymes, using several methods, in which one is based upon miniaturized cell cultures and automated expression screening in microwell plates (Alberto et al. 2009). (...

Molecular phylogeny of Trametes and related genera, and description of a new genus Leiotrametes

A phylogenetic analysis of and related taxa is proposed, based on a wide sampling of temperate and tropical species. Concatenate sequences of ribosomal DNA (ITS1-5.8S-ITS2) and RPB2 gene from mycelia cultures were analyzed by Maximum Likelihood and Bayesian methods, whilst morphological features were documented from the corresponding herbarium vouchers. Congruent results were obtained from analyses of ribosomal LSU sequences downloaded from Genbank. The Bayesian analysis of ITS + RPB2 sequences gave the best resolution for the phylogenetic reconstructions and revealed the existence of three main lineages in the -clade: 1) a monospecific lineage represented by 2) a lineage including the genus in its traditional sense and several species usually classified in the genus (, , , ) & 3) a lineage corresponding to the core genus , including type species of , and . The presence of a pseudostipe, aspect and structure of the abhymenial surface, colour change with 5% aqueous solutions of potassium hydroxide and topography of pigments on skeletal hyphae gave relevant morphological support to these clades. When the structure of the hymenial surface, presence of a black line below the tomentum and color of context (except for genus ) usually used in traditional polypore-classifications did not reveal any phylogenetic significance. A partial systematic arrangement of the clade is proposed, with the introduction of a new genus: Welti & Courtec. .. Two new combinations: (Berk.) Welti & Courtec. . and (Berk.) Welti & Courtec. . are proposed

Post-genomic analyses of fungal lignocellulosic biomass degradation reveal the unexpected potential of the plant pathogen Ustilago maydis

<p>Abstract</p> <p>Background</p> <p>Filamentous fungi are potent biomass degraders due to their ability to thrive in ligno(hemi)cellulose-rich environments. During the last decade, fungal genome sequencing initiatives have yielded abundant information on the genes that are putatively involved in lignocellulose degradation. At present, additional experimental studies are essential to provide insights into the fungal secreted enzymatic pools involved in lignocellulose degradation.</p> <p>Results</p> <p>In this study, we performed a wide analysis of 20 filamentous fungi for which genomic data are available to investigate their biomass-hydrolysis potential. A comparison of fungal genomes and secretomes using enzyme activity profiling revealed discrepancies in carbohydrate active enzymes (CAZymes) sets dedicated to plant cell wall. Investigation of the contribution made by each secretome to the saccharification of wheat straw demonstrated that most of them individually supplemented the industrial <it>Trichoderma reesei </it>CL847 enzymatic cocktail. Unexpectedly, the most striking effect was obtained with the phytopathogen <it>Ustilago maydis </it>that improved the release of total sugars by 57% and of glucose by 22%. Proteomic analyses of the best-performing secretomes indicated a specific enzymatic mechanism of <it>U. maydis </it>that is likely to involve oxido-reductases and hemicellulases.</p> <p>Conclusion</p> <p>This study provides insight into the lignocellulose-degradation mechanisms by filamentous fungi and allows for the identification of a number of enzymes that are potentially useful to further improve the industrial lignocellulose bioconversion process.</p

Conserved white-rot enzymatic mechanism for wood decay in the Basidiomycota genus Pycnoporus

White-rot (WR) fungi are pivotal decomposers of dead organic matter in forest ecosystems and typically use a large array of hydrolytic and oxidative enzymes to deconstruct lignocellulose. However, the extent of lignin and cellulose degradation may vary between species and wood type. Here, we combined comparative genomics, transcriptomics and secretome proteomics to identify conserved enzymatic signatures at the onset of wood-decaying activity within the Basidiomycota genus Pycnoporus. We observed a strong conservation in the genome structures and the repertoires of protein-coding genes across the four Pycnoporus species described to date, despite the species having distinct geographic distributions. We further analysed the early response of P. cinnabarinus, P. coccineus and P. sanguineus to diverse (ligno)-cellulosic substrates. We identified a conserved set of enzymes mobilized by the three species for breaking down cellulose, hemicellulose and pectin. The co-occurrence in the exo-proteomes of H2O2-producing enzymes with H2O2-consuming enzymes was a common feature of the three species, although each enzymatic partner displayed independent transcriptional regulation. Finally, cellobiose dehydrogenase-coding genes were systematically co-regulated with at least one AA9 lytic polysaccharide monooxygenase gene, indicative of enzymatic synergy in vivo. This study highlights a conserved core white-rot fungal enzymatic mechanism behind the wood-decaying process.Peer reviewe

Extraction d'hydroxytyrosol

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Activité de l'eau et conservation des aliments

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Contribution a l'etude de l'influence des lipides des grains et graines sur la croissance des moisissures xerotolerantes

6 illus., ref. *CR de Nantes - Laboratoire de Microbiologie et Technologie Cerealieres Diffusion du document : CR de Nantes - Laboratoire de Microbiologie et Technologie Cerealieres Diplôme : Dr. d'Universit