The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Anu Koivula - One of the best experts on this subject based on the ideXlab platform.
-
improving the thermostability and activity of melanocarpus albomyces cellobiohydrolase cel7b
Applied Microbiology and Biotechnology, 2009Co-Authors: Sanni Voutilainen, Marika Alapuranen, Jari Vehmaanpera, Harry Boer, Janne Janis, Anu KoivulaAbstract:Two different types of approach were taken to improve the hydrolytic activity towards crystalline cellulose at elevated temperatures of Melanocarpus albomyces Cel7B (Ma Cel7B), a single-module GH-7 family cellobiohydrolase. Structure-guided protein engineering was used to introduce an additional tenth disulphide bridge to the Ma Cel7B catalytic module. In addition, a fusion protein was constructed by linking a cellulose-binding module (CBM) and a linker from the Trichoderma reesei Cel7A to the C terminus of Ma Cel7B. Both approaches proved successful. The disulphide bridge mutation G4C/M70C located near the N terminus, close to the entrance of the active site tunnel of Ma Cel7B, led to improved thermostability (ΔT m = 2.5°C). By adding the earlier found thermostability-increasing mutation S290T (ΔT m = 1.5°C) together with the disulphide bridge mutation, the unfolding temperature was increased by 4°C (mutant G4C/M70C/S290T) compared to that of the wild-type enzyme, thus showing an additive effect on thermostability. Both disulphide mutants had increased activity towards microcrystalline cellulose (Avicel) at 75°C, apparently solely because of their improved thermostability. The addition of a CBM also improved the thermostability (ΔT m = 2.5°C) and caused a clear (sevenfold) increase in the hydrolysis activity of Ma Cel7B towards Avicel at 70°C.
-
heterologous expression of melanocarpus albomyces cellobiohydrolase cel7b and random mutagenesis to improve its thermostability
Enzyme and Microbial Technology, 2007Co-Authors: Sanni Voutilainen, Jari Vehmaanpera, Juha Rouvinen, Harry Boer, Markus Linder, Terhi Puranen, Anu KoivulaAbstract:Abstract Fungal cellobiohydrolases from the glycosyl hydrolase family 7 are key enzymes in crystalline cellulose hydrolysis. Difficulties in heterologous expression in a bacterial or yeast host have hampered engineering of these cellulases for industrial application. We report here a successful expression of the single-module cellobiohydrolase Cel7B from a thermophilic fungus Melanocarpus albomyces in Saccharomyces cerevisiae (Sc Cel7B). An automated, robotic thermostability screening method, based on residual activity measurements on a small soluble substrate methylumbelliferyl-lactoside (MULac), was then set-up to screen the first generation random mutant libraries. Out of the nine positive thermostable mutants, we picked three based on structural considerations, each containing a single amino acid change (A30T, G184D or S290T). Cel7B A30T and S290T mutants showed improved unfolding temperature (Tm) by 1.5 and 3.5 °C, respectively. In addition, the temperature optimum (Topt) on a soluble substrate had improved by 5 °C for the A30T mutant. Interestingly, the best enzyme variant on microcrystalline cellulose (Avicel) hydrolysis was the Cel7B S290T, which could hydrolyse Avicel at 70 °C two times more effectively than the Sc Cel7B. Overall the consensus mutation S290T, located in the hydrophobic core of Cel7B, led to a cellobiohydrolase variant having also application potential in hydrolysis of polymeric substrates at elevated temperatures.
-
crystal structure of a laccase from melanocarpus albomyces with an intact trinuclear copper site
Nature Structural & Molecular Biology, 2002Co-Authors: Nina Hakulinen, Anu Koivula, Lauraleena Kiiskinen, Kristiina Kruus, Markku Saloheimo, Arja Paananen, Juha RouvinenAbstract:We have crystallized the ascomycete laccase from Melanocarpus albomyces with all four coppers present and determined the crystal structure at 2.4 A resolution. The enzyme is heavily glycosylated and consists of three cupredoxin-like domains, similar to those found in the Cu-depleted basidiomycete laccase from Coprinus cinereus. However, there are significant differences in the loops forming the substrate-binding pocket. In addition, the crystal structure of the M. albomyces laccase revealed elongated electron density between all three coppers in the trinuclear copper site, suggesting that an oxygen molecule binds with a novel geometry. This oxygen, required in the reaction, may enter the trinuclear site through the tunnel, which is open in the structure of the C. cinereus laccase. In contrast, the C-terminus on the M. albomyces laccase forms a plug that blocks this access.
Timothy Y. James - One of the best experts on this subject based on the ideXlab platform.
-
ultrastructural characterization of the host parasite interface between Allomyces anomalus blastocladiomycota and rozella allomycis cryptomycota
Fungal Biology, 2017Co-Authors: Martha J. Powell, Peter M Letcher, Timothy Y. JamesAbstract:Rozella allomycis is an obligate endoparasite of the water mold Allomyces and a member of a clade (= Opisthosporidia) sister to the traditional Fungi. Gaining insights into Rozella's development as a phylogenetically pivotal endoparasite can aid our understanding of structural adaptations and evolution of the Opisthosporidia clade, especially within the context of genomic information. The purpose of this study is to characterize the interface between R. allomycis and Allomyces anomalus. Electron microscopy of developing plasmodia of R. allomycis in host hyphae shows that the interface consists of three-membrane layers, interpreted as the parasite's plasma membrane (inner one layer) and a host cisterna (outer two layers). As sporangial and resting spore plasmodia develop, host mitochondria typically cluster at the surface of the parasite and eventually align parallel to the three-membrane layered interface. The parasite's mitochondria have only a few cristae and the mitochondrial matrix is sparse, clearly distinguishing parasite mitochondria from those of the host. Consistent with the expected organellar topology if the parasite plasmodia phagocytize host cytoplasm, phagocytic vacuoles are at first bounded by three-membrane layers with host-type mitochondria lining the inner membrane. Thus, Rozella's nutrition, at least in part, is phagotrophic in contrast to osmotrophic nutrition of traditional fungi.
-
ARTICLES Reconstructing the early evolution of Fungi using a six-gene phylogeny
2016Co-Authors: Timothy Y. James, Frank Kauff, Gail Celio, Emily Fraker, Jolanta Miadlikowska, Thorsten H Lumbsch, Conrad L. Schoch, Cymon J. Cox, Ra RauhutAbstract:The ancestors of fungi are believed to be simple aquatic forms with flagellated spores, similar to members of the extant phylum Chytridiomycota (chytrids). Current classifications assume that chytrids form an early-diverging clade within the kingdom Fungi and imply a single loss of the spore flagellum, leading to the diversification of terrestrial fungi. Here we develop phylogenetic hypotheses for Fungi using data from six gene regions and nearly 200 species. Our results indicate that theremay have been at least four independent losses of the flagellum in the kingdomFungi. These losses of swimming spores coincidedwith the evolution of newmechanisms of spore dispersal, such as aerial dispersal inmycelial groups and polar tube eversion in the microsporidia (unicellular forms that lack mitochondria). The enigmatic microsporidia seem to be derived from an endoparasitic chytrid ancestor similar to Rozella allomycis, on the earliest diverging branch of the fungal phylogenetic tree. Fungi, Viridiplantae andAnimalia are all large clades descended fro
-
Morphological, molecular, and ultrastructural characterization of Rozella rhizoclosmatii, a new species in Cryptomycota.
Fungal Biology, 2016Co-Authors: C. Alisha Quandt, Domingos Da Silva Leite, Timothy Y. JamesAbstract:Abstract Rozella is a genus of unwalled endoparasites of a variety of hosts including Oomycota (Stramenopiles), Blastocladiomycota and Chytridiomycota (Fungi), and one green alga ( Coleochaete , Chlorophyceae). It currently includes more than 20 formally described species, and no new species of Rozella have been described since 1987. We discovered a new Rozella species parasitizing Rhizoclosmatium globosum (Chytridiales, Chytridiomycota) and investigated its morphology, ultrastructure, and phylogenetic position. Herein named as Rozella rhizoclosmatii sp. nov., the organism induces hypertrophy of the host. Its zoospore is ultrastructurally similar to that of Rozella allomycis , although it has a unique zoospore ultrastructural feature, a lattice of perpendicular rods about the nucleus. The 18S rDNA molecular sequence of R. rhizoclosmatii is similar to that of the previously sequenced ‘ Rozella ex Rhizoclosmatium ’. This is the first study to inclusively characterize a new species of Rozella with morphological, ultrastructural and molecular data. As this is only the second Rozella species to be examined ultrastructurally, and because it is parasitic on a member of Chytridiomycota and not Blastocladiomycota, this research supports the conservative nature of zoospore ultrastructure to help define the genus.
-
Molecular phylogeny of the Blastocladiomycota (Fungi) based on nuclear ribosomal DNA.
Fungal Biology, 2011Co-Authors: Teresita M Porter, Timothy Y. James, Frank H. Gleason, Wallace Martin, Joyce E Longcore, Peter H Adler, Peter M Letcher, Rytas VilgalysAbstract:The Blastocladiomycota is a recently described phylum of ecologically diverse zoosporic fungi whose species have not been thoroughly sampled and placed within a molecular phylogeny. In this study, we investigated the phylogeny of the Blastocladiomycota based on ribosomal DNA sequences from strains identified by traditional morphological and ultrastructural characters. Our results support the monophyly of the Coelomomycetaceae and Physodermataceae but the Blastocladiaceae and Catenariaceae are paraphyletic or polyphyletic. The data support two clades within Allomyces with strains identified as Allomyces arbusculus in both clades, suggesting that species concepts in Allomyces are in need of revision. A clade of Catenaria species isolated from midge larvae group separately from other Catenaria species, suggesting that this genus may need revision. In the Physodermataceae, Urophlyctis species cluster with a clade of Physoderma species. The algal parasite Paraphysoderma sedebokerensis nom. prov. clusters sister to other taxa in the Physodermataceae. Catenomyces persicinus, which has been classified in the Catenariaceae, groups with the Chytridiomycota rather than Blastocladiomycota. The rDNA operon seems to be suitable for classification within the Blastocladiomycota and distinguishes among genera; however, this region alone is not suitable to determine the position of the Blastocladiomycota among other basal fungal phyla with statistical support. A focused effort to find and isolate, or directly amplify DNA from additional taxa will be necessary to evaluate diversity in this phylum. We provide this rDNA phylogeny as a preliminary framework to guide further taxon and gene sampling and to facilitate future ecological, morphological, and systematic studies.
-
reconstructing the early evolution of fungi using a six gene phylogeny
Nature, 2006Co-Authors: Timothy Y. James, Frank Kauff, Valerie Hofstetter, Gail Celio, Cecile Gueidan, Emily Fraker, Jolanta Miadlikowska, Conrad L. Schoch, Brandon P Matheny, Thorsten H LumbschAbstract:The ancestors of fungi are believed to be simple aquatic forms with flagellated spores, similar to members of the extant phylum Chytridiomycota (chytrids). Current classifications assume that chytrids form an early-diverging clade within the kingdom Fungi and imply a single loss of the spore flagellum, leading to the diversification of terrestrial fungi. Here we develop phylogenetic hypotheses for Fungi using data from six gene regions and nearly 200 species. Our results indicate that there may have been at least four independent losses of the flagellum in the kingdom Fungi. These losses of swimming spores coincided with the evolution of new mechanisms of spore dispersal, such as aerial dispersal in mycelial groups and polar tube eversion in the microsporidia (unicellular forms that lack mitochondria). The enigmatic microsporidia seem to be derived from an endoparasitic chytrid ancestor similar to Rozella allomycis, on the earliest diverging branch of the fungal phylogenetic tree.
Jari Vehmaanpera - One of the best experts on this subject based on the ideXlab platform.
-
improving the thermostability and activity of melanocarpus albomyces cellobiohydrolase cel7b
Applied Microbiology and Biotechnology, 2009Co-Authors: Sanni Voutilainen, Marika Alapuranen, Jari Vehmaanpera, Harry Boer, Janne Janis, Anu KoivulaAbstract:Two different types of approach were taken to improve the hydrolytic activity towards crystalline cellulose at elevated temperatures of Melanocarpus albomyces Cel7B (Ma Cel7B), a single-module GH-7 family cellobiohydrolase. Structure-guided protein engineering was used to introduce an additional tenth disulphide bridge to the Ma Cel7B catalytic module. In addition, a fusion protein was constructed by linking a cellulose-binding module (CBM) and a linker from the Trichoderma reesei Cel7A to the C terminus of Ma Cel7B. Both approaches proved successful. The disulphide bridge mutation G4C/M70C located near the N terminus, close to the entrance of the active site tunnel of Ma Cel7B, led to improved thermostability (ΔT m = 2.5°C). By adding the earlier found thermostability-increasing mutation S290T (ΔT m = 1.5°C) together with the disulphide bridge mutation, the unfolding temperature was increased by 4°C (mutant G4C/M70C/S290T) compared to that of the wild-type enzyme, thus showing an additive effect on thermostability. Both disulphide mutants had increased activity towards microcrystalline cellulose (Avicel) at 75°C, apparently solely because of their improved thermostability. The addition of a CBM also improved the thermostability (ΔT m = 2.5°C) and caused a clear (sevenfold) increase in the hydrolysis activity of Ma Cel7B towards Avicel at 70°C.
-
hydrolysis of amorphous and crystalline cellulose by heterologously produced cellulases of melanocarpus albomyces
Journal of Biotechnology, 2008Co-Authors: Nora Szijarto, Matti Siikaaho, Maija Tenkanen, Marika Alapuranen, Jari Vehmaanpera, Kati Reczey, Liisa ViikariAbstract:Three thermostable neutral cellulases from Melanocarpus albomyces, a 20-kDa endoglucanase (Cel45A), a 50-kDa endoglucanase (Cel7A), and a 50-kDa cellobiohydrolase (Cel7B) heterologously produced in a recombinant Trichoderma reesei were purified and studied in hydrolysis (50 ◦ C, pH 6.0) of crystalline and amorphous cellulose. To improve their efficiency, M. albomyces cellulases naturally harboring no cellulose-binding module (CBM) were genetically modified to carry the CBM of T. reesei CBHI/Cel7A, and were studied under similar experimental conditions. Hydrolysis performance and product profiles were used to evaluate hydrolytic features of the investigated enzymes. Each cellulase proved to be active against the tested substrates; the cellobiohydrolase Cel7B had greater activity than the endoglucanases Cel45A and Cel7A against crystalline cellulose, whereas in the case of amorphous substrate the order was reversed. Evidence of synergism was observed when mixtures of the novel enzymes were applied in a constant total protein dosage. Presence of the CBM improved the hydrolytic potential of each enzyme in all experimental configurations; it had a greater effect on the endoglucanases Cel45A and Cel7A than the cellobiohydrolase Cel7B, especially against crystalline substrate. The novel cellobiohydrolase performed comparably to the major cellobiohydrolase of T. reesei (CBHI/Cel7A) under the applied experimental conditions. © 2008 Elsevier B.V. All rights reserved.
-
heterologous expression of melanocarpus albomyces cellobiohydrolase cel7b and random mutagenesis to improve its thermostability
Enzyme and Microbial Technology, 2007Co-Authors: Sanni Voutilainen, Jari Vehmaanpera, Juha Rouvinen, Harry Boer, Markus Linder, Terhi Puranen, Anu KoivulaAbstract:Abstract Fungal cellobiohydrolases from the glycosyl hydrolase family 7 are key enzymes in crystalline cellulose hydrolysis. Difficulties in heterologous expression in a bacterial or yeast host have hampered engineering of these cellulases for industrial application. We report here a successful expression of the single-module cellobiohydrolase Cel7B from a thermophilic fungus Melanocarpus albomyces in Saccharomyces cerevisiae (Sc Cel7B). An automated, robotic thermostability screening method, based on residual activity measurements on a small soluble substrate methylumbelliferyl-lactoside (MULac), was then set-up to screen the first generation random mutant libraries. Out of the nine positive thermostable mutants, we picked three based on structural considerations, each containing a single amino acid change (A30T, G184D or S290T). Cel7B A30T and S290T mutants showed improved unfolding temperature (Tm) by 1.5 and 3.5 °C, respectively. In addition, the temperature optimum (Topt) on a soluble substrate had improved by 5 °C for the A30T mutant. Interestingly, the best enzyme variant on microcrystalline cellulose (Avicel) hydrolysis was the Cel7B S290T, which could hydrolyse Avicel at 70 °C two times more effectively than the Sc Cel7B. Overall the consensus mutation S290T, located in the hydrophobic core of Cel7B, led to a cellobiohydrolase variant having also application potential in hydrolysis of polymeric substrates at elevated temperatures.
-
three cellulases from melanocarpus albomyces for textile treatment at neutral ph
Enzyme and Microbial Technology, 2004Co-Authors: Arja Miettinenoinonen, John Londesborough, Vesa Joutsjoki, Raija Lantto, Jari VehmaanperaAbstract:Abstract Culture supernatants from strains of Melanocarpus albomyces, Myceliophthora thermophila, Chaetomium thermophilum, and Sporotrichum thermophilum were tested for their ability to release dye in neutral pH conditions from indigo-dyed cotton-containing fabric in biostoning applications. The supernatants from M. albomyces worked well in biostoning, with low backstaining. Three cellulases were purified to homogeneity from the culture medium of this species. Two of the cellulases were endoglucanases with apparent molecular masses of 20 and 50 kDa. The 20 kDa endoglucanase was a relatively heat-stable cellulase with high pH optimum. The partially purified enzyme crystallized spontaneously at pH 4.0 and 7 °C. The 50 kDa endoglucanase also had activity against 4-methylumbelliferyl-β- d -lactoside (MUL) and was active over a wide range of pH values. The third purified cellulase was the 50 kDa cellobiohydrolase with low MUL activity at acidic pH and detectable activity towards filter paper and acid swollen Solca Floc-cellulose, but no endoglucanase activity. The purified 20 kDa endoglucanase performed well in biostoning of denim fabric at neutral pH. Addition of the purified 50 kDa endoglucanase or the 50 kDa cellobiohydrolase to the 20 kDa endoglucanase decreased backstaining in biostoning.
Peter M Letcher - One of the best experts on this subject based on the ideXlab platform.
-
ultrastructure of early stages of rozella allomycis cryptomycota infection of its host Allomyces macrogynus blastocladiomycota
Fungal Biology, 2019Co-Authors: Martha J. Powell, Peter M LetcherAbstract:Abstract This study reconstructs early stages of Rozella allomycis endoparasitic infection of its host, Allomyces macrogynus. Young thalli of A. macrogynus were inoculated with suspensions of R. allomycis zoospores and allowed to develop for 120 h. Infected thalli at intervals were fixed for electron microscopy and observed. Zoospores were attracted to host thalli, encysted on their surfaces, and penetrated their walls with an infection tube. The parasite cyst discharged its protoplast through an infection tube, which invaginated the host plasma membrane. The host plasma membrane then surrounded the parasite protoplast and formed a compartment confining it inside host cytoplasm. The earliest host-parasite interface within host cytoplasm consisted of two membranes, the outer layer the host plasma membrane and the inner layer the parasite plasma membrane. At first a wide space separated the two membranes and no material was observed within this space. Later, as the endoparasite thallus expanded within the compartment, the two membranes became closely appressed. As the endoparasite thallus continued to enlarge, the interface developed into three membrane layers. Thus, host plasma membrane surrounded the parasite protoplast initially without the parasite having to pierce the host plasma membrane for entry. Significantly, host-derived membrane was at the interface throughout development.
-
ultrastructural characterization of the host parasite interface between Allomyces anomalus blastocladiomycota and rozella allomycis cryptomycota
Fungal Biology, 2017Co-Authors: Martha J. Powell, Peter M Letcher, Timothy Y. JamesAbstract:Rozella allomycis is an obligate endoparasite of the water mold Allomyces and a member of a clade (= Opisthosporidia) sister to the traditional Fungi. Gaining insights into Rozella's development as a phylogenetically pivotal endoparasite can aid our understanding of structural adaptations and evolution of the Opisthosporidia clade, especially within the context of genomic information. The purpose of this study is to characterize the interface between R. allomycis and Allomyces anomalus. Electron microscopy of developing plasmodia of R. allomycis in host hyphae shows that the interface consists of three-membrane layers, interpreted as the parasite's plasma membrane (inner one layer) and a host cisterna (outer two layers). As sporangial and resting spore plasmodia develop, host mitochondria typically cluster at the surface of the parasite and eventually align parallel to the three-membrane layered interface. The parasite's mitochondria have only a few cristae and the mitochondrial matrix is sparse, clearly distinguishing parasite mitochondria from those of the host. Consistent with the expected organellar topology if the parasite plasmodia phagocytize host cytoplasm, phagocytic vacuoles are at first bounded by three-membrane layers with host-type mitochondria lining the inner membrane. Thus, Rozella's nutrition, at least in part, is phagotrophic in contrast to osmotrophic nutrition of traditional fungi.
-
Molecular phylogeny of the Blastocladiomycota (Fungi) based on nuclear ribosomal DNA.
Fungal Biology, 2011Co-Authors: Teresita M Porter, Timothy Y. James, Frank H. Gleason, Wallace Martin, Joyce E Longcore, Peter H Adler, Peter M Letcher, Rytas VilgalysAbstract:The Blastocladiomycota is a recently described phylum of ecologically diverse zoosporic fungi whose species have not been thoroughly sampled and placed within a molecular phylogeny. In this study, we investigated the phylogeny of the Blastocladiomycota based on ribosomal DNA sequences from strains identified by traditional morphological and ultrastructural characters. Our results support the monophyly of the Coelomomycetaceae and Physodermataceae but the Blastocladiaceae and Catenariaceae are paraphyletic or polyphyletic. The data support two clades within Allomyces with strains identified as Allomyces arbusculus in both clades, suggesting that species concepts in Allomyces are in need of revision. A clade of Catenaria species isolated from midge larvae group separately from other Catenaria species, suggesting that this genus may need revision. In the Physodermataceae, Urophlyctis species cluster with a clade of Physoderma species. The algal parasite Paraphysoderma sedebokerensis nom. prov. clusters sister to other taxa in the Physodermataceae. Catenomyces persicinus, which has been classified in the Catenariaceae, groups with the Chytridiomycota rather than Blastocladiomycota. The rDNA operon seems to be suitable for classification within the Blastocladiomycota and distinguishes among genera; however, this region alone is not suitable to determine the position of the Blastocladiomycota among other basal fungal phyla with statistical support. A focused effort to find and isolate, or directly amplify DNA from additional taxa will be necessary to evaluate diversity in this phylum. We provide this rDNA phylogeny as a preliminary framework to guide further taxon and gene sampling and to facilitate future ecological, morphological, and systematic studies.
Sanni Voutilainen - One of the best experts on this subject based on the ideXlab platform.
-
improving the thermostability and activity of melanocarpus albomyces cellobiohydrolase cel7b
Applied Microbiology and Biotechnology, 2009Co-Authors: Sanni Voutilainen, Marika Alapuranen, Jari Vehmaanpera, Harry Boer, Janne Janis, Anu KoivulaAbstract:Two different types of approach were taken to improve the hydrolytic activity towards crystalline cellulose at elevated temperatures of Melanocarpus albomyces Cel7B (Ma Cel7B), a single-module GH-7 family cellobiohydrolase. Structure-guided protein engineering was used to introduce an additional tenth disulphide bridge to the Ma Cel7B catalytic module. In addition, a fusion protein was constructed by linking a cellulose-binding module (CBM) and a linker from the Trichoderma reesei Cel7A to the C terminus of Ma Cel7B. Both approaches proved successful. The disulphide bridge mutation G4C/M70C located near the N terminus, close to the entrance of the active site tunnel of Ma Cel7B, led to improved thermostability (ΔT m = 2.5°C). By adding the earlier found thermostability-increasing mutation S290T (ΔT m = 1.5°C) together with the disulphide bridge mutation, the unfolding temperature was increased by 4°C (mutant G4C/M70C/S290T) compared to that of the wild-type enzyme, thus showing an additive effect on thermostability. Both disulphide mutants had increased activity towards microcrystalline cellulose (Avicel) at 75°C, apparently solely because of their improved thermostability. The addition of a CBM also improved the thermostability (ΔT m = 2.5°C) and caused a clear (sevenfold) increase in the hydrolysis activity of Ma Cel7B towards Avicel at 70°C.
-
heterologous expression of melanocarpus albomyces cellobiohydrolase cel7b and random mutagenesis to improve its thermostability
Enzyme and Microbial Technology, 2007Co-Authors: Sanni Voutilainen, Jari Vehmaanpera, Juha Rouvinen, Harry Boer, Markus Linder, Terhi Puranen, Anu KoivulaAbstract:Abstract Fungal cellobiohydrolases from the glycosyl hydrolase family 7 are key enzymes in crystalline cellulose hydrolysis. Difficulties in heterologous expression in a bacterial or yeast host have hampered engineering of these cellulases for industrial application. We report here a successful expression of the single-module cellobiohydrolase Cel7B from a thermophilic fungus Melanocarpus albomyces in Saccharomyces cerevisiae (Sc Cel7B). An automated, robotic thermostability screening method, based on residual activity measurements on a small soluble substrate methylumbelliferyl-lactoside (MULac), was then set-up to screen the first generation random mutant libraries. Out of the nine positive thermostable mutants, we picked three based on structural considerations, each containing a single amino acid change (A30T, G184D or S290T). Cel7B A30T and S290T mutants showed improved unfolding temperature (Tm) by 1.5 and 3.5 °C, respectively. In addition, the temperature optimum (Topt) on a soluble substrate had improved by 5 °C for the A30T mutant. Interestingly, the best enzyme variant on microcrystalline cellulose (Avicel) hydrolysis was the Cel7B S290T, which could hydrolyse Avicel at 70 °C two times more effectively than the Sc Cel7B. Overall the consensus mutation S290T, located in the hydrophobic core of Cel7B, led to a cellobiohydrolase variant having also application potential in hydrolysis of polymeric substrates at elevated temperatures.