Renato Chavez

Renato Chavez
University of Santiago, Chile | USACH · Departamento de Biología

Dr. Biological Sciences

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89
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Publications

Publications (89)
Article
Chloride ions are toxic for most acidophilic microorganisms. In this study, the chloride tolerance mechanisms in the acidophilic iron-oxidizing bacterium Leptospirillum ferriphilum DSM 14647 adapted to 180 mM NaCl were investigated by a transcriptomic approach. Results showed that 99 genes were differentially expressed in the adapted versus the non...
Article
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The discovery of penicillin entailed a decisive breakthrough in medicine. No other medical advance has ever had the same impact in the clinical practise. The fungus Penicillium chrysogenum (reclassified as P. rubens) has been used for industrial production of penicillin ever since the forties of the past century; industrial biotechnology developed...
Article
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Endoxylanases belonging to family 10 of the glycoside hydrolases (GH10) are versatile in the use of different substrates. Thus, an understanding of the molecular mechanisms underlying substrate specificities could be very useful in the engineering of GH10 endoxylanases for biotechnological purposes. Herein, we analyzed XynA, an endoxylanase that co...
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Novel species of fungi described in this study include those from various countries as follows: Antartica, Cladosporium austrolitorale from coastal sea sand. Australia, Austroboletus yourkae on soil, Crepidotus innuopurpureus on dead wood, Curvularia stenotaphri from roots and leaves of Stenotaphrum secundatum and Thecaphora stajsicii from capsules...
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The genus Pseudogymnoascus represents a diverse group of fungi widely distributed in different cold regions on Earth. Our current knowledge of the species of Pseudogymnoascus is still very limited. Currently, there are only 15 accepted species of Pseudogymnoascus that have been isolated from different environments in the Northern Hemisphere. In con...
Article
The oxidative stress response represents a sum of antioxidative mechanisms that are essential for determining the adaptation and abundance of microorganisms in the environment. Leptospirillum ferriphilum and Acidithiobacillus ferrooxidans are chemolithotrophic bacteria that obtain their energy from the oxidation of ferrous ion. Both microorganisms...
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In the food industry, some fungi are considered to be common spoilage microorganisms which reduce the shelf life of products. To avoid this outcome, different technologies are being developed to control their growth. Electromagnetic fields (EMF) have been used to combat bacterial growth, but there are few studies on yeasts and their possible action...
Article
Draft genomes of Penicillium roqueforti, Fusarium sororula, Chalaropsis populi, and Chrysoporthe puriensis are presented. Penicillium roqueforti is a model fungus for genetics, physiological and metabolic studies, as well as for biotechnological applications. Fusarium sororula and Chrysoporthe puriensis are important tree pathogens, and Chalaropsis...
Article
Optical networks have been positioned as high-speed networks whose switches must respond to requests at rates that did not occur before, determining that static traffic evolving into dynamic traffic caused the routing problem, and the wavelength assignment cannot be solved with optimization processes, giving rise to the appearance of heuristic algo...
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Novel species of fungi described in this study include those from various countries as follows: Antarctica, Cladosporium arenosum from marine sediment sand. Argentina, Kosmimatamyces alatophylus (incl. Kosmimatamyces gen. nov.) from soil. Australia, Aspergillus banksianus, Aspergillus kumbius, Aspergillus luteorubrus, Aspergillus malvicolor and Asp...
Article
For most acidophilic iron-oxidizing bioleaching microorganisms, chloride ions are toxic even at low concentrations since they are able to induce an acidification of the cytoplasm and osmotic stress. To identify molecular determinants for osmotic tolerance of these microorganisms, a genomic analysis based on the complete genomes of twelve iron oxidi...
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Thioredoxin fold proteins (TFPs) form a family of diverse proteins involved in thiol/disulfide exchange in cells from all domains of life. Leptospirillum spp. are bioleaching bacteria naturally exposed to extreme conditions like acidic pH and high concentrations of metals that can contribute to the generation of reactive oxygen species (ROS) and co...
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Las redes ópticas se han posicionado como redes de alta velocidad donde sus conmutadores deben responder a solicitudes a tasas que antes no ocurrían, esto determinó que el tráfico estático evolucionar a tráfico dinámico generó que el problema de enrutamiento y asignación de longitud onda no pueda ser resuelto con procesos de optimización, dando lug...
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Novel species of fungi described in this study include those from various countries as follows: Antarctica , Apenidiella antarctica from permafrost, Cladosporium fildesense from an unidentified marine sponge. Argentina , Geastrum wrightii on humus in mixed forest. Australia , Golovinomyces glandulariae on Glandularia aristigera , Neoanungitea eucal...
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Cold-adapted fungi isolated from Antarctica, in particular those belonging to the genus Pseudogymnoascus, are producers of secondary metabolites with interesting bioactive properties as well as enzymes with potential biotechnological applications. However, at genetic level, the study of these fungi has been hindered by the lack of suitable genetic...
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In acidophilic microorganisms, anions like chloride have higher toxicity than their neutrophilic counterparts. In addition to the osmotic imbalance, chloride can also induce acidification of the cytoplasm. We predicted that intracellular acidification produces an increase in respiratory rate and generation of reactive oxygen species, and so oxidati...
Chapter
Antarctica is one of the most unexplored environments on the Earth. This continent is permanently subjected to very low temperatures and other extreme conditions. However, despite these harsh environmental conditions, many species of filamentous fungi inhabit Antarctica. These fungi would have developed different strategies to survive in this polar...
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Brettanomyces bruxellensis has been described as the principal spoilage yeast in the winemaking industry. To avoid its growth, wine is supplemented with SO2, which has been questioned due to its potential harm to health. For this reason, studies are being focused on searching for, ideally, natural new antifungals. On the other hand, it is known tha...
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La actividad y estabilidad de las enzimas está condicionada, entre otras variables, a la temperatura. Dado que los organismos antárticos viven generalmente sometidos a bajas temperaturas, sus enzimas son excelentes modelos para estudiar la adaptación de estas proteínas al ambiente frío. Con el apoyo de INACH, nuestro grupo ha purificado, por primer...
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Background: Pectinase enzymes catalyze the breakdown of pectin, a key component of the plant cell wall. At industrial level, pectinases are used in diverse applications, especially in food-processing industry. Currently, most of the industrial pectinases have optimal activity at mesophilic temperatures. On the contrary, very little is known about...
Article
Penicillium roqueforti is used in the production of several kinds of ripened blue-veined cheeses. In addition, this fungus produces interesting secondary metabolites such as roquefortine C, andrastin A and mycophenolic acid. To date, there is scarce information concerning the regulation of the production of these secondary metabolites. Recently, th...
Article
Numerous endoxylanases from mesophilic fungi have been purified and characterized. However, endoxylanases from cold-adapted fungi, especially those from Antarctica, have been less studied. In this work, a cDNA from the Antarctic fungus Cladosporium sp. with similarity to endoxylanases from glycosyl hydrolase family 10, was cloned and expressed in P...
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The sfk1 (suppressor of four kinase) gene has been mainly studied in Saccharomyces cerevisiae, where it was shown to be involved in growth and thermal stress resistance. This gene is widely conserved within the phylum Ascomycota. Despite this, to date sfk1 has not been studied in any filamentous fungus. Previously, we found that the orthologous of...
Article
The fungus Penicillium camemberti is widely used in the ripening of various bloomy-rind cheeses. Several properties of P. camemberti are important in cheese ripening, including conidiation, growth and enzyme production, among others. However, the production of mycotoxins such as cyclopiazonic acid during the ripening process by P. camemberti has ra...
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Penicillium roqueforti is a filamentous fungus involved in the ripening of several kinds of blue cheeses. In addition, this fungus produces several secondary metabolites, including the meroterpenoid compound andrastin A, a promising antitumoral compound. However, to date the genomic cluster responsible for the biosynthesis of this compound in P. ro...
Article
Full-text available
Penicillium roqueforti is a filamentous fungus involved in the ripening of several kinds of blue cheeses. In addition, this fungus produces several secondary metabolites, including the meroterpenoid compound andrastin A, a promising antitumoral compound. However, to date the genomic cluster responsible for the biosynthesis of this compound in P. ro...
Article
Bioleaching processes are used to recover metals from sulfidic ores. Biofilm formation on ores is important for bioleaching because the attached microorganisms start the leaching process by concentrating ferric ions in the extracellular matrix. It has been shown that hydrogen peroxide is spontaneously generated on the surface of ores and that it ne...
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The unexplored geobiological heritage of Chile: key tounderstand the past and future.activity at low temperature. 1094 microorganisms (960 bacteria, 33 yeast and 101 filamentous fungi) previously isolated from different Antarctic environments were screened for -galactosidase activity at 5 ◦C, 10 ◦C and 15 ◦C using plates with X-gal (molecule analog...
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Members of the genus Leptospirillum are aerobic iron-oxidizing bacteria belonging to the phylum Nitrospira. They are important members of microbial communities that catalyze the biomining of sulfidic ores, thereby solubilizing metal ions. These microorganisms live under extremely acidic and metal-loaded environments and thus must tolerate high conc...
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The filamentous fungus Penicillium roqueforti is widely known as the ripening agent of blue-veined cheeses. Additionally, this fungus is able to produce several secondary metabolites, including the meroterpenoid compound mycophenolic acid (MPA). Cheeses ripened with P. roqueforti are usually contaminated with MPA. On the other hand, MPA is a commer...
Data
Result of RACE-PCR experiments performed on the mpaB and mpaDE genes from P. roqueforti (A) The 3`end cDNA sequence of mpaB obtained by using 3´-RACE-PCR is shown in blue. Above this sequence, the sequence of the deduced intron is shown in black. The arrow indicates the site where the intron interrupts the coding sequence. The stop codon predicted...
Data
Comparison between the mpa clusters of P. roqueforti and P. brevicompactum by dot-plot. Above the plot, a simplified scheme of mpa cluster is shown. Diagonal continuous lines represent pairwise alignments matching with coding regions. Please note that the intergenic regions do not shown significant alignments, suggesting strong differences in these...
Data
Correlation coefficient (R2), slope and efficiency of calibration curves obtained for the mpa genes from P. roqueforti analyzed by qRT-PCR (PDF)
Data
(A) Diagrams of the empty expression cassette with a single NcoI cloning site in the original silencing vector pJL43-RNAi (left) and the same expression cassette with a fragment of a mpa gene (right). The small black arrows represent primers ConfRNAiFW (5´- GCATGCCATTAACCTAGG -3´) and ConfRNAiRV (5´-ACGGTGGCTGAAGATTC -3´), which were used to confir...
Data
Representative trace chromatograms at 300 nm for the RNAi-silenced transformants of P. roqueforti. In each chromatogram, the gene silenced (mpaA to mpaH) is indicated. For comparison purposes, the chromatogram for the wild-type strain (WT) is also included. All the chromatograms are in the same scale (0.0 to 0.3 units of absorbance and 0 to 25 minu...
Data
General representation of the plasmids constructed for each gene from the mpa cluster. Pgpd and PpcbC represent the convergent promoters from the gpd gene from A. nidulans and the pcbC gene from P. chrysogenum. The grey box represents a fragment of the inserted exon. Seven plasmids were constructed and each one was named pJL-RNAi-mpaX, where X iden...
Data
(A) Part of the output of a BlastX search using ORF Proq05g069780a as query. According to our analysis, Proq05g069780a has 788 excess nucleotides at the 5´ end. As a consequence, according to BlastX, the first hit (belonging to CDM36724, the deduced product of Proq05g069780a itself) contains two introns (one of them huge) and two additional small e...
Data
MPA levels in mycelium and agar from cultures of P. roqueforti. For a best comparison, data from the P. roqueforti wild-type (plot A) and RNAi-silenced transformants (plot B) are shown separately. For simplicity, in plot B only one transformant is shown for each gene: T7 (mpaA), T7 (mpaB), T5 (mpaC), T2 (mpaDE), T4 (mpaF), T3 (mpaG) and T5 (mpaH)....
Data
Sequence of the primers used in qRT-PCR experiments for each mpa gene from P. roqueforti. The name of each primer and the size of the amplicon generated with each pair of primers are also included. (PDF)
Data
(A) Part of the output of a BlastX search using ORF Proq05g069810 as the query. Please note that compared with the rest of the hits, the first hit belonging to CDM36727 (the deduced product of Proq05g069810 itself) lacks the carboxyl end encoded by the last exon, suggesting that Proq05g069810 may span a larger region than that described by the orig...
Data
Plasmids generated for the RNAi-mediated silencing of the mpa genes from P. roqueforti. The size of the insert ligated in each plasmid and the sequence of the primers used for the amplification of each insert are also included. (PDF)
Article
Leptospirillum ferriphilum is an acidophilic iron-oxidizing bacterium that is relevant for chemical leaching of sulfide ores. In the extremely acidic conditions found in bioleaching operations, this microorganism deals with an abundant supply of soluble iron and other metals that might induce oxidative damage to biomolecules through the generation...
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Natural product search is undergoing resurgence upon the discovery of a huge previously unknown potential for secondary metabolite (SM) production hidden in microbial genomes. This is also the case for filamentous fungi, since their genomes contain a high number of “orphan” SM gene clusters. Recent estimates indicate that only 5% of existing fungal...
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Proteins containing Zn(II) 2 Cys 6 domains are exclusively found in fungi and yeasts. Genes encoding this class of proteins are broadly distributed in fungi, but few of them have been functionally characterized. In this work, we have characterized a gene from the filamentous fungus Penicillium roqueforti that encodes a Zn(II) 2 Cys 6 protein, whose...
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Four new nitroasterric acid derivatives, pseudogymnoascins A-C (1-3) and 3-nitroasterric acid (4), along with the two known compounds questin and pyriculamide, were obtained from the cultures of a Pseudogymnoascus sp. fungus isolated from an Antarctic marine sponge belonging to the genus Hymeniacidon. The structures of the new compounds were determ...
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We report Nitrincola sp. strain A-D6, which was characterized as an arsenic-resistant bacterium isolated from the Ascotán Salt Flat in northern Chile. The size of the genome is 3,795,776 bp, with a G+C content of 49.96%. Genes for the arsenic-resistant Ars system and arsenic oxidation have been encoded.
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A basidiomycetous yeast, strain E2A-C3-II, was isolated from a marine sponge (Hymeniacidon sp.) collected at a depth of 6 m in Fildes Bay, King George Island, Antarctica. The phylogenetic analysis revealed that the yeast isolated is related to Leucosporidium drummii, Leucosporidiella muscorum and to the Leucosporidium scottii group, including Leuco...
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During the characterization of the micobiota associated with shallow-water marine environments from Antarctic sea, a novel pink-colored yeast species was isolated. Sequence analysis of the D1/D2 domain of the LSU rDNA gene and 5.8S-ITS regions revealed that the yeast isolated is closely related to Rhodotorula pallida CBS 320T and Rhodotorula benthi...
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The diversity of sponge-associated fungi has been poorly investigated in remote geographical areas like Antarctica. In this study, 101 phenotypically different fungal isolates were obtained from 11 sponge samples collected in King George Island, Antarctica. The analysis of ITS sequences revealed that they belong to the phylum Ascomycota. Sixty-five...
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Thiol/disulfide systems are involved in the maintenance of the redox status of proteins and other molecules that contain thiol/disulfide groups. Leptospirillum ferriphilum DSM14647, an acidophilic bacterium that uses Fe(2+) as electron donor, and withstands very high concentrations of iron and other redox active metals, is a good model to study how...
Data
Phylogram of predicted thioredoxin from Leptospirillum “5 way CG”. Deduced amino acid sequences of Trx (Trx1-Trx12) were aligned with proteins of known function belonging to Trx family. The proteins used in this analysis were TrxA, TrxC, TrxG, DsbA, DsbC, DsbD, DsbE, DsbG, CcdA, and peroxiredoxins Prx1 and Prx2. The proteins sequences were obtained...
Article
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Unlike filamentous fungi and bacteria, very little is known about cultivable yeasts associated with marine sponges, especially those from Antarctic seas. During an expedition to King George Island, in the Antarctica, samples of 11 marine sponges were collected by scuba-diving. From these sponges, 20 psychrotolerant yeast isolates were obtained. Phy...
Article
Chemolithoautotrophic acidophilic bacteria, which belong to the genus Leptospirillum, can only grow with Fe(II) as electron donor and oxygen as an electron acceptor. Members of this genus play an important role in bioleaching sulfide ores. We used nearly complete genome sequences of Leptospirillum ferrooxidans (group I), Leptospirillum rubarum, Lep...
Article
The heterologous secretion of xylanase B from Penicillium purpurogenum using glucose as inducer was performed in Aspergillus nidulans. For this purpose, plasmid pEVXB, containing the xylanase B cDNA (including its own signal peptide) under the control of the glyceraldehyde-3-phosphate dehydrogenase promoter, was constructed and used to transform A....
Article
The biotechnological applications of cheese-ripening fungi have been limited by a lack of genetics tools, in particular the identification and characterization of suitable promoters for protein expression. In this study, the suitability of the glyceraldehyde-3-phosphate dehydrogenase (gpdP) promoter from Penicillium camemberti to drive the producti...
Chapter
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Fungi have been used to elaborate fermented foods by many cultures throughout the world since ancient times. Many filamentous fungi are currently used in food processing both in eastern and western countries. As food processors, filamentous fungi participate in different aspects during the elaboration of the product, contributing to its ripening, a...
Article
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A protocol for preparative isopenicillin N (IPN) purification, a highly interesting and hitherto unavailable intermediate of the penicillin and cephalosporin biosynthetic pathway due to its high unstability, is described. Culture broths of Acremonium chrysogenum TD189, a strain blocked in cephalosporin biosynthesis that accumulates this metabolite,...
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Strains of Penicillium camemberti and Penicillium roqueforti were tested for properties that could be important for future biotechnological applications of these fungi. Penicillium camemberti CECT 2267 and P. roqueforti NRRL 849 showed the most promising performances in terms of growth, protoplast production, and protoplast regeneration abilities....
Article
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Genetic manipulation of the filamentous fungus Penicillium camemberti has been limited by a lack of suitable genetics tools for this fungus. In particular, there is no available homologous transformation system. In this study, the nitrate reductase (niaD) and orotidine-5'-monophosphate decarboxylase (pyrG) genes from Penicillium camemberti were cha...
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Heterotrimeric G protein signaling regulates many processes in fungi, such as development, pathogenicity, and secondary metabolite biosynthesis. For example, the Galpha subunit Pga1 from Penicillium chrysogenum regulates conidiation and secondary metabolite production in this fungus. The dominant activating allele, pga1G42R, encoding a constitutive...
Article
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Molecular characterization of the niaD and pyrG genes from Penicillium camemberti, and its uses as transformation markers. , 14(4):