The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Marc-andré Lachance - One of the best experts on this subject based on the ideXlab platform.
-
Yeast communities associated with cacti in Brazil and the description of Kluyveromyces starmeri sp. nov. based on phylogenomic analyses.
Yeast (Chichester England), 2020Co-Authors: Larissa F D Freitas, Marc-andré Lachance, Thiago M Batista, Ana R O Santos, Heron O Hilário, Rennan G Moreira, Glória R Franco, Paula B Morais, Carlos A RosaAbstract:Yeast communities associated with cacti were studied in three ecosystems of Southeast, Central and North Brazil. A total of 473 yeast strains belonging to 72 species were isolated from 190 samples collected. Cactophilic yeast species were prevalent in necrotic tissues, flowers, fruits and insects of cacti collected in Southeast and North Brazil. Pichia cactophila, Candida sonorensis and species of the Sporopachydermia complex were the most prevalent cactophilic species in Southeast and Central regions. Kodamaea nitidulidarum, Candida restingae and Wickerhamiella cacticola were frequently associated with cactus flowers and fruits. The diversity of yeasts associated with the substrates studied was high. Twenty-one novel species were found. One is described here as Kluyveromyces starmeri sp. nov. based on 21 isolates obtained from necrotic tissues, flowers, fruits and associated insects of the columnar cacti Cereus saddianus, Micranthocereus dolichospermaticus and Pilosocereus arrabidae in two different ecosystems in Brazil. Phylogenetic analyses of sequences encoding the gene of the small subunit (SSU) rRNA gene, the internal transcribed spacer, the 5.8S rRNA gene and the D1/D2 domains of the large subunit (LSU) rRNA showed that the species is related to Kluyveromyces dobzhanskii, Kluyveromyces lactis and Kluyveromyces marxianus. Phylogenomic analyses based on 1264 conserved genes shared among the new species and 19 other members of the Saccharomycetaceae confirmed this phylogenetic relationship. The holotype is K. starmeri sp. nov. CBS 16103T (=UFMG-CM-Y3682T ). The Mycobank number is MB 836817.
-
Kluyveromyces van der Walt (1971)
The Yeasts, 2011Co-Authors: Marc-andré LachanceAbstract:Publisher Summary This chapter studies the genus Kluyveromyces. In the determination of asexual reproduction, multilateral budding occurs on a narrow base. Cells are ovoid, ellipsoid, cylindrical, or elongate. Pseudohyphae may be formed, but true hyphae are not produced. In sexual reproduction it is seen that conjugation may or may not precede ascus formation. The ascospores are smooth, reniform, bacilliform, ellipsoidal, or spherical and tend to agglutinate after liberation. One to four ascospores are formed per ascus. In physiology and biochemistry it is seen that glucose is fermented vigorously by most species. This study further examines the phylogenetic placement. The type of species mentioned is Kluyveromyces marxianus. The species accepted are Kluyveromyces aestuarii, Kluyveromyces dobzhanskii, Kluyveromyces lactis, Kluyveromyces marxianus, Kluyveromyces nonfermentans, and Kluyveromyces wickerhamii. The systematic discussion of the species includes synonyms, growth on YM agar, growth in glucose yeast extract broth, Dalmau plate culture on corn meal agar, CoQ, Mol% G1C, gene sequence accession number, type strain, cell carbohydrates, formation of ascospores, origin of the strains studied, complementary mating types, systematics, ecology, biotechnology, agriculture and food, and clinical importance.
-
Current status of Kluyveromyces systematics
FEMS yeast research, 2007Co-Authors: Marc-andré LachanceAbstract:A brief outline of the current taxonomic status of the genus Kluyveromyces is presented. Noteworthy are the transfer of several former Kluyveromyces species to other genera, the retention of the name Kluyveromyces for K. lactis, K. marxianus, and four related species, and some recent attempts to clarify the variety status of strains assigned to K. lactis.
-
Kluyveromyces bacillisporus sp. nov., a Yeast
1993Co-Authors: Marc-andré Lachance, Herman J. Phaff, William T. StarmerAbstract:Three strains of a new diploid species of the genus Kluyveromyces van der Walt emend. van der Walt were isolated from exudates of Emory oak (@ercus emoryi) trees in Arizona. In physiological characteristics and nuclear DNA base composition (38 mol% G+C) these isolates most closely resemble Kluyveromyces afiicanus and KZuyveromyces delphensis, but the three taxa are genetically unrelated, as shown by DNA reassociation and ribosomal DNA restriction mapping. The morphology of these organisms is typical of the genus Kluyveromyces, except that the mature ascospores (four and occasionally more spores per ascus) are characteristically bacilliform rather than spheroidal, ellipsoidal, or reniform. Mitochondria1 DNA (21 mol% G+C) is present in unusually large proportions (ca. one-half of the total DNA). The type strain of Kluyveromyces bacilcispoms sp. nov. is strain UWO(PS) 85-349.2 (= ATCC 90019 = CBS 7720). Emory oak (Quercus emolyi Torr.) produces seasonal exudates which harbor an interesting yeast flora (2). Drosophila species visit these exudates, as well as those of nearby cottonwoods (Populus fiemontii Wats.), with the result that these two trees exhibit some overlap in their yeast compositions. However, the yeast community of Emory oak is more typical of that of other oaks (1, 7, 9) in that it contains species such as Pichia pastoris, Saccharomyces dairensis, Kluyveromyces lactis var. drosophilarum , or Candida norvegica, as well as other less specific yeasts, such as Saccharomyces cerevisiae. Some samples contain a previously unknown species of the genus Kluyveromyces, described in this paper as Kluyveromyces bacillispow . MATERIALS AND METHODS
-
Kluyveromyces bacillisporus sp. nov., a Yeast from Emory Oak Exudate
International Journal of Systematic Bacteriology, 1993Co-Authors: Marc-andré Lachance, Herman J. Phaff, William T. StarmerAbstract:Three strains of a new diploid species of the genus Kluyveromyces van der Walt emend. van der Walt were isolated from exudates of Emory oak (Quercus emoryi) trees in Arizona. In physiological characteristics and nuclear DNA base composition (38 mol% G+C) these isolates most closely resemble Kluyveromyces africanus and Kluyveromyces delphensis, but the three taxa are genetically unrelated, as shown by DNA reassociation and ribosomal DNA restriction mapping. The morphology of these organisms is typical of the genus Kluyveromyces, except that the mature ascospores (four and occasionally more spores per ascus) are characteristically bacilliform rather than spheroidal, ellipsoidal, or reniform. Mitochondrial DNA (21 mol% G+C) is present in unusually large proportions (ca. one-half of the total DNA). The type strain of Kluyveromyces bacillisporus sp. nov. is strain UWO(PS) 85-349.2 (= ATCC 90019 = CBS 7720).
A. Miclo - One of the best experts on this subject based on the ideXlab platform.
-
Yeast continuous mixed cultures on whey permeate and hydrolysed starch
Process Biochemistry, 2001Co-Authors: H. Kallel-mhiri, C. Valance, Jean-marc Engasser, A. MicloAbstract:Abstract Mixed cultures of Saccharomyces cerevisiae CBS 8066 and Kluyveromyces fragilis were used for continuous biomass production on media containing whey permeate and glucose (WG) or whey permeate, maltose and glucose (WGM). Glucose and maltose were provided from a totally or a partially hydrolysed starch. For each medium the effects of two yeast extract concentrations (0.1 and 0.5 g/litre) were investigated. The yeast extract concentration markedly affected the equilibrium of the co-culture and the cell yield which was also influenced by the dilution rate. The yield varied from 0.26 to 0.48 g/g. The results obtained were due to the different kinetics of glucose transport in Kluyveromyces fragilis and Saccharomyces cerevisiae. Kluyveromyces fragilis possessed two glucose carriers, present at all the tested dilution rates, characterised by their affinity constants which were much higher than those present in Saccharomyces cerevisiae .
-
Mechanism of ethyl acetate synthesis by Kluyveromyces fragilis
FEMS Microbiology Letters, 1993Co-Authors: H. Kallel-mhiri, A. MicloAbstract:The enzymes implicated in ethyl acetate synthesis and the catabolism of ethanol by Kluyveromyces fragilis were investigated under varying growth conditions. The culture was grown continuously to D = 0.25 h−1 on diluted whey permeate. The results showed that ethyl acetate synthesis by Kluyveromyces fragilis is catalysed by both an esterase and an alcohol acetyltransferase. The esterase is a constitutive enzyme, while alcohol acetyltransferase is inducible. The catabolism of ethanol by Kluyveromyces fragilis resulted in production of ethyl acetate, acetate and acetaldehyde. The glyoxylic shunt is totally inactive in these conditions. The production of acetaldehyde is only governed by an alcohol dehydrogenase.
Isabel Rocha - One of the best experts on this subject based on the ideXlab platform.
-
Genome-wide metabolic (re-) annotation of Kluyveromyces lactis
BMC genomics, 2012Co-Authors: Oscar Dias, Andreas Karoly Gombert, Eugénio C. Ferreira, Isabel RochaAbstract:Background Even before having its genome sequence published in 2004, Kluyveromyces lactis had long been considered a model organism for studies in genetics and physiology. Research on Kluyveromyces lactis is quite advanced and this yeast species is one of the few with which it is possible to perform formal genetic analysis. Nevertheless, until now, no complete metabolic functional annotation has been performed to the proteins encoded in the Kluyveromyces lactis genome.
-
Genome-wide metabolic (re-) annotation of Kluyveromyces lactis
BMC Genomics, 2012Co-Authors: Oscar Dias, Andreas Karoly Gombert, Eugénio C. Ferreira, Isabel RochaAbstract:Background Even before having its genome sequence published in 2004, Kluyveromyces lactis had long been considered a model organism for studies in genetics and physiology. Research on Kluyveromyces lactis is quite advanced and this yeast species is one of the few with which it is possible to perform formal genetic analysis. Nevertheless, until now, no complete metabolic functional annotation has been performed to the proteins encoded in the Kluyveromyces lactis genome. Results In this work, a new metabolic genome-wide functional re-annotation of the proteins encoded in the Kluyveromyces lactis genome was performed, resulting in the annotation of 1759 genes with metabolic functions, and the development of a methodology supported by merlin (software developed in-house). The new annotation includes novelties, such as the assignment of transporter superfamily numbers to genes identified as transporter proteins. Thus, the genes annotated with metabolic functions could be exclusively enzymatic (1410 genes), transporter proteins encoding genes (301 genes) or have both metabolic activities (48 genes). The new annotation produced by this work largely surpassed the Kluyveromyces lactis currently available annotations. A comparison with KEGG’s annotation revealed a match with 844 (~90%) of the genes annotated by KEGG, while adding 850 new gene annotations. Moreover, there are 32 genes with annotations different from KEGG. Conclusions The methodology developed throughout this work can be used to re-annotate any yeast or, with a little tweak of the reference organism, the proteins encoded in any sequenced genome. The new annotation provided by this study offers basic knowledge which might be useful for the scientific community working on this model yeast, because new functions have been identified for the so-called metabolic genes. Furthermore, it served as the basis for the reconstruction of a compartmentalized, genome-scale metabolic model of Kluyveromyces lactis , which is currently being finished.
Andreas Karoly Gombert - One of the best experts on this subject based on the ideXlab platform.
-
Genome-wide metabolic (re-) annotation of Kluyveromyces lactis
BMC genomics, 2012Co-Authors: Oscar Dias, Andreas Karoly Gombert, Eugénio C. Ferreira, Isabel RochaAbstract:Background Even before having its genome sequence published in 2004, Kluyveromyces lactis had long been considered a model organism for studies in genetics and physiology. Research on Kluyveromyces lactis is quite advanced and this yeast species is one of the few with which it is possible to perform formal genetic analysis. Nevertheless, until now, no complete metabolic functional annotation has been performed to the proteins encoded in the Kluyveromyces lactis genome.
-
Genome-wide metabolic (re-) annotation of Kluyveromyces lactis
BMC Genomics, 2012Co-Authors: Oscar Dias, Andreas Karoly Gombert, Eugénio C. Ferreira, Isabel RochaAbstract:Background Even before having its genome sequence published in 2004, Kluyveromyces lactis had long been considered a model organism for studies in genetics and physiology. Research on Kluyveromyces lactis is quite advanced and this yeast species is one of the few with which it is possible to perform formal genetic analysis. Nevertheless, until now, no complete metabolic functional annotation has been performed to the proteins encoded in the Kluyveromyces lactis genome. Results In this work, a new metabolic genome-wide functional re-annotation of the proteins encoded in the Kluyveromyces lactis genome was performed, resulting in the annotation of 1759 genes with metabolic functions, and the development of a methodology supported by merlin (software developed in-house). The new annotation includes novelties, such as the assignment of transporter superfamily numbers to genes identified as transporter proteins. Thus, the genes annotated with metabolic functions could be exclusively enzymatic (1410 genes), transporter proteins encoding genes (301 genes) or have both metabolic activities (48 genes). The new annotation produced by this work largely surpassed the Kluyveromyces lactis currently available annotations. A comparison with KEGG’s annotation revealed a match with 844 (~90%) of the genes annotated by KEGG, while adding 850 new gene annotations. Moreover, there are 32 genes with annotations different from KEGG. Conclusions The methodology developed throughout this work can be used to re-annotate any yeast or, with a little tweak of the reference organism, the proteins encoded in any sequenced genome. The new annotation provided by this study offers basic knowledge which might be useful for the scientific community working on this model yeast, because new functions have been identified for the so-called metabolic genes. Furthermore, it served as the basis for the reconstruction of a compartmentalized, genome-scale metabolic model of Kluyveromyces lactis , which is currently being finished.
-
Heterologous expression of a thermophilic esterase in Kluyveromyces yeasts.
Applied microbiology and biotechnology, 2010Co-Authors: Saul Nitsche Rocha, Andreas Karoly Gombert, José Abrahão-neto, María Esperanza Cerdán, María Isabel González-sisoAbstract:In the present work, a thermophilic esterase from Thermus thermophilus HB27 was cloned into Kluyveromyces marxianus and into Kluyveromyces lactis using two different expression systems, yielding four recombinant strains. K. lactis showed the highest esterase expression levels (294 units per gram dry cell weight, with 65% of cell-bound enzyme) using an episomal system with the PGK promoter and terminator from Saccharomyces cerevisiae combined with the K. lactis k1 secretion signal. K. marxianus showed higher secretion efficiency of the heterologous esterase (56.9 units per gram dry cell weight, with 34% of cell-bound enzyme) than K. lactis. Hydrolytic activities for the heterologous esterases were maximum at pH values between 8.0 and 9.0 for both yeast species and at temperatures of 50 °C and 45 °C for K. marxianus and K. lactis, respectively. When compared to previously published data on this same esterase produced in the original host or in S. cerevisiae, our results indicate that Kluyveromyces yeasts can be considered good hosts for the heterologous secretion of thermophilic esterases, which have a potential application in biodiesel production or in resolving racemates.
H. Kallel-mhiri - One of the best experts on this subject based on the ideXlab platform.
-
Yeast continuous mixed cultures on whey permeate and hydrolysed starch
Process Biochemistry, 2001Co-Authors: H. Kallel-mhiri, C. Valance, Jean-marc Engasser, A. MicloAbstract:Abstract Mixed cultures of Saccharomyces cerevisiae CBS 8066 and Kluyveromyces fragilis were used for continuous biomass production on media containing whey permeate and glucose (WG) or whey permeate, maltose and glucose (WGM). Glucose and maltose were provided from a totally or a partially hydrolysed starch. For each medium the effects of two yeast extract concentrations (0.1 and 0.5 g/litre) were investigated. The yeast extract concentration markedly affected the equilibrium of the co-culture and the cell yield which was also influenced by the dilution rate. The yield varied from 0.26 to 0.48 g/g. The results obtained were due to the different kinetics of glucose transport in Kluyveromyces fragilis and Saccharomyces cerevisiae. Kluyveromyces fragilis possessed two glucose carriers, present at all the tested dilution rates, characterised by their affinity constants which were much higher than those present in Saccharomyces cerevisiae .
-
Mechanism of ethyl acetate synthesis by Kluyveromyces fragilis
FEMS Microbiology Letters, 1993Co-Authors: H. Kallel-mhiri, A. MicloAbstract:The enzymes implicated in ethyl acetate synthesis and the catabolism of ethanol by Kluyveromyces fragilis were investigated under varying growth conditions. The culture was grown continuously to D = 0.25 h−1 on diluted whey permeate. The results showed that ethyl acetate synthesis by Kluyveromyces fragilis is catalysed by both an esterase and an alcohol acetyltransferase. The esterase is a constitutive enzyme, while alcohol acetyltransferase is inducible. The catabolism of ethanol by Kluyveromyces fragilis resulted in production of ethyl acetate, acetate and acetaldehyde. The glyoxylic shunt is totally inactive in these conditions. The production of acetaldehyde is only governed by an alcohol dehydrogenase.