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PubMedDate not supplied

[Utilization of aromatic compounds by yeasts of the genus Debaryomyces].

The ability to utilize phenol, catechol, resorcinol, hydroquinone, p-hydroxybenzoic acid, m-hydroxybenzoic acid, 2,4-dihydroxydenzoic acid, protocatechuic and gentisic acids was studied among 61 strains of 23 yeast species belonging to the Debaryomyces genus. All species characterized by active fermentation did not utilize these aromatic compounds. If fermentation was absent or weak, some of the aromatic compounds were utilized. This fact suggests an ecological difference between the two above yeast groups, justifying the subdivision of the Debaryomyces genus by some authors into two genera Debaryomyces and Torulaspora. No correlation could be established between the utilization of certain aromatic compounds and the yeast species classified on the basis of their behaviour toward carbohydrates. Therefore, classification of yeasts belonging to the Debaryomyces genus is artificial. It would be expedient to isolate a small number of typical species unless a more accurate relationship is established between cultures of the Debaryomyces genus referred to as different species.

Ascomycota↗
PubMed2026

The role of HIL1 in strain-level adhesion and immune recognition in Debaryomyces hansenii.

UNLABELLED: Strains of food-derived microbes can become facultative pathogens in susceptible human hosts. Surprisingly, we previously isolated Debaryomyces hansenii, a yeast common in fermented foods, from Crohn disease (CD) ulcers, raising questions about its strain-specific traits that influence host interactions. Here, we further developed the genetic tractability of D. hansenii and identified a single adhesin, Hil1, as a major determinant of colony morphology, biofilm formation, and immune targeting in CD patients. We used Agrobacterium tumefaciens-mediated transformation to perform a forward genetic screen in a food-derived reference strain. We isolated mutants that converted from a wrinkled, biofilm-forming phenotype to a smooth, non-adherent phenotype characteristic of CD patient isolates. Mapping of multiple insertion sites showed a disrupted subtelomeric Hyr/Iff-like adhesin gene, herein referred to as HIL1. CRISPR-Cas9-mediated deletion of HIL1 recapitulated the mutant phenotype, demonstrating that HIL1 was necessary for biofilm formation and high cell-surface hydrophobicity phenotypes. To contextualize these findings, we performed comparative genomics on a D. hansenii strain collection to assess allelic variation in the number of HIL1 tandem repeats. Longer alleles in food strains correlated with increased biofilm formation, while CD-isolated strains contained shorter HIL1 alleles and reduced binding to surfaces. Serology profiling showed that HIL1 was a direct antigenic target of circulating immunoglobulin G (IgG) in CD patients. Together, these results suggest Hil1 is a key, strain-variable adhesin shaping fungal surface properties and host immune recognition. This work establishes D. hansenii as a genetically tractable system and shows how adhesin polymorphisms may influence fungal behavior in food and disease contexts. IMPORTANCE: Debaryomyces hansenii is a yeast that is common in food and is generally recognized as safe for human consumption, though recently it has been identified within diseased regions of the intestine in Crohn disease patients. A current need is to determine the genetic and phenotypic differences between safe food isolates and isolates from human Crohn disease patient ulcers. Here, we used a loss-of-function genetic screen and identified HIL1, an adhesin that we found mediates cellular adhesion in many food strains but not in patient strains. We identified circulating HIL1-reactive antibodies in patients with Crohn disease, indicating that food strains can be a target of host immune responses through Hil1.

Humans↗
PubMed1977

Ploidy, ascus formation and recombination in Torulaspora (Debaryomyces) hansenii.

X-ray inactivation studies on the type strain of Torulaspora hansenii carried out to determine ploidy, provided proof that the species has a haplontic life cycle, a fact which hitherto has only been presumed. Observations on the genesis of the ascus by light microscopy and transmission electron microscopy provide no evidence for, what some earlier workers in this field have presumed to be, heterogamous conjugation between a mother cell and its bud. They do, however, show that asci, bearing obliquely-attached, vestigal, bud-like appendages, arise from some cells to form single, non-abstricting, and frequently, recurving protuberances which enlarge. These could, conceivably, be responsible for the impression that abstricted buds are connected to the mother-cells by bent copulatory tubes. The formation during sporulation of elongated protuberances and the presence of a medial, electron-dense line within the electron-translucent layer of the walls of ascospores fixed with OsO4 preclude the possibility of using these features to differentiate between the genera Torulaspora and Debaryomyces. Furthermore, recombinant studies, which involved the use of auxotrophic mutants, indicated that during sporulation the fusion of independent cells accounted for only 0.03-0.6% of the asci formed. The conclusion was reached that somatogamous autogamy must be the main agency of diploidization and that the species is largely inbreeding.

Conjugation, Genetic↗
PubMed1975

Scanning electron microscopy of ascospores of Debaryomyces and Saccharomyces.

Ascospores from species of Debaryomyces and the Torulaspora-group of Saccharomyces were examined by scanning electron microscopy. Ornamentation on ascospores of D. hansenii varied from short to long interconnected ridges or broad based, elongated conical protuberances. A spiral rigde system was detected on the ascospores of D. marama, but wart-like protuberances occurred on those of D. cantarelli, D. castellii, D. coudertii, D. formicarius, D. phaffii, D. vanriji and D. yarrowii. Ascospores of D. halotolerans did not have protuberances and the species appears to be identical with Pichia farinosa. Wart-like protuberances also were found on ascospores of S. delbrueckii, S. microellipsodes, S. rosei, S. inconspicuus, S. fermentati, S. montanus and S. vafer, but the ascospore surface of S. pretoriensis was covered by fine ridges. Short tapered ridges covered the ascospores of S. kloeckerianus.

Cell Wall↗
PubMed1976

On the mechanism of salt tolerance. Production of glycerol and heat during growth of Debaryomyces hansenii.

As glycerol was suggested as an osmotic agent in the salt tolerant Debaryomyces hansenii the concentrations of total, intracellular, and extracellular glycerol produced by this yeast was followed during growth in 4 mM, 0.68 M, and 2.7 M NaCl media. The total amount of glycerol was not directly proportional to biomass production but to the cultural salinity with maximum concentrations just prior to or at the beginning of the stationary phase. In all cultures the cells lost some glycerol to the media, at 2.7 M NaCl the extracellular glycerol even amounted maximally to 80% of the total. A distinct maximum of intracellular glycerol, related to dry weight or cell number, appeared during the log phase at all NaCl concentrations. As the intracellular calculated glycerol concentrations amounted to 0.2 M, 0.8 M, and 2.6 M in late log phase cells at 4mM, 0.68 M, and 2.7 M NaCl, respectively, whereas the corresponding analysed values for the glycerol concentrations of the media were 0.7 mM, 2.5 mM, and 3.0 mM, glycerol contributes to the osmotic balance of the cells. During the course of growth all cultures showed a decreasing heat production related to cell substance produced, most pronounced at 2.7 M NaCl. At 2.7 M NaCl the total heat production amounted to--1690 kJ per mole glucose consumed in contrast to--1200 and--1130 kJ at 4 mM and 0.68 M NaCl, respectively. The Ym-values were of an inverse order, being 129, 120, and 93 at 4 mM, 0.68 M, and 2.7 M NaCl respectively.

Ascomycota↗
PubMed1978

Properties of alkaline phosphatase of the halotolerant yeast Debaryomyces hansenii.

The molecular weight of a partially purified alkaline phosphatase (orthophosphoric-monoester phosphohydrolase, EC 3.1.3.1) from the halotolerant yeast Debaryomyces hansenii was estimated to 110,000 by gel filtration. The isoelectric point determined by electrofocusing was at approximately pH 4.4. The enzyme had a broad specificity against phosphomonoesters and also attacked some acid anhydrides. Arsenate, molybdate, and orthophosphate acted as competitive inhibitors. Various metal-binding agents inhibited enzyme activity. A zinc addition almost completely reversed the EDTA inhibition. Magnesium stimulated enzyme activity and was required for maintenance of activity at high concentrations of Na+. Increasing glycerol concentration increased the value of the Michaelis constant (Km) and decreased the maximum velocity (V). Solutions equimolar in KCl and NaCl stimulated enzyme activity by increasing V, whereas the Km was almost unaffected by salt concentration. Enzyme extracted from cells cultured at low salinity was indistinguishable from that of cells grown in the presence of 2.7 M NaCl with respect to several criteria.

Alkaline Phosphatase↗
PubMed1975

Electron microscopy of ascus formation in the yeast debaryomyces hansenii.

Ascus formation in Debaryomyces hansenii includes fusion of two cells, usually mother and daughter while still attached to each other, through short protuberances developed from the cross wall between them. Nuclear fusion takes place in the channel connecting the two cells; meiosis apparently occurs in the mother cell. Generally, only one lobe of the meiotic nucleus is surrounded by a prospore wall and it becomes the nucleus of a spore with a warty wall. The rest of the nucleus disappears. The spores germinate by swelling in the ascus and forming one or more buds.

Cell Fusion↗
PubMed1976

Purification of alkaline phosphatase of the halotolerant yeast Debaryomyces hansenii.

Alkaline phosphatase (orthophosphoric monoester phosphohydrolase, EC 3.1.3.1) of the halotolerant yeast Debaryomyces hansenii was purified by a procedure involving cell disruption, DNAase treatment, ethanol precipitation, gel filtration, chromatography on DEAE-Sephadex, and preparative polyacrylamide gel electrophoresis. The specific activity was increased 1250-fold as compared to the activity of cell free extract. The total recovery was 30%. Various modifications of the growth conditions had slight or no effect on the yield of enzyme.

Alkaline Phosphatase↗
PubMedDate not supplied

The antigenic relationship between Brettanomyces-Debaryomyces strains and the Salmonella cholerae-suis O antigen.

The immune sera for Brettanomyces lambicus, B. claussenii, Debaryomyces hansenii and D. marama agglutinated Salmonella cholerae-suis (0:6(2), 7). The immune serum for S. cholerae-suis agglutinated B. lambicus, B. clausenni, D. hansenii and D. marama. Absorption and agglutination cross-tested demonstrated common antigen factor(s) in the tested yeasts and Salmonella 0:7 antigen.

Antigens, Bacterial↗
PubMedDate not supplied

[Candida mogii and Debaryomyces hansenii yeast development in the presence of metal chlorides].

The yeasts Candida mogii 2 and Debaryomyces hansenii 8 isolated from salted fish spawn in the process of its storage were found to be capable of growth in 4 M KCl, 3 M MgCl2, 2.5 M NaCl, 1.5 BaCl2 and 1 M CaCl2. The activity of water (aw) in these solutions varied from 0.983 to 0.719; the maximum osmotic pressure was 380 atm. The cultures grew also in a 3 M sucrose solution, at low concentrations of osmotically active substances and without them. Therefore, they can be regarded as osmotolerant microorganisms. The osmotolerance of the cultures decreased with temperature of solutions. The absence of growth or weak growth in solutions of certain other chlorides should be attributed to toxicity of cations.

Candida↗
PubMed1978

The effect of the water activity of the milieu on rates of glucose uptake by the osmophilic yeasts Saccharomyces rouxii and Debaryomyces hansenii.

Rates of glucose uptake in baker's yeast and in the osmophilic yeasts D. hansenii and S. rouxii were investigated at different values of water activity of the milieu, as regulated either by glycerol or sodium chloride. In both cases, D. hansenii could maintain relatively higher rates of glucose uptake. At lower values of water activity, sodium chloride exerted an inhibitory effect on rates of glucose uptake by S. rouxii, while in the presence of glycerol, rates of glucose uptake shown by S. rouxii resembled those shown by D. hansenii. Rates of glucose uptake by baker's yeast were drastically affected at lower values of water activity in the presence of either solute. Lower values of water activity exerted a stimulatory effect on catalase activity of both S. rouxii and D. hansenii. However, activities of baker's yeast with regard to catalase and invertase were moderately affected under such conditions. Results presented may lead to the presumption that osmophilic yeasts, at least partly, have solved the problem of osmotic tolerance over nonosmotolerant strains by possessing a high capacity for maintaining higher rates of glucose uptake, in spite of the adverse external concentration of solute.

Catalase↗
PubMed1976

[Systematic study of Saccharomyces: oxidases and vitamin requirements].

A study of the genus Saccharomyces by new biocharacters demonstrates indirectly the genotype of each species; intracellular osidases (lactose - maltose -cellobiase - melibiase - invertase - trehalase) and vitamin requirements (biotin-folic acid-inositol-niacine-pantothénate-para-aminobenzoic acid-pyridozine-thiamine) reveal some phylogenetic links between the species. It appears that Van der Walt's group I is very homogeneous and must be restricted to only 7 species. The torulospora group seems very similar to the genus Debaryomyces when vitamin needs and osidases are considered; the relations between the 2 groups are discussed. When other biocharacters are studied (nitrite reductase-immunological properties, etc. ...) the value in the GC content (4-5% lower in Debaryomyces) will be established. These results confirm that intracellular oxidases and vitamin needs are very valuable tools for systematic criteria.

Oxidoreductases↗
PubMed1979

Screening studies of yeasts capable of utilizing petroleum fractions.

In these studies, 23 yeast cultures belonging to 10 genera of ascosporogenous, ballistosporogenous, and asporogenous yeasts, were screened with respect to their abilities of hydrocarbon utilization in synthetic media. Thus, kerosene, n-hexadecane, and wax distillate were compared as sole carbon sources in 2% final concentration. Kerosene exhibited marked inhibition on the growth of the majority of the strains, whereas active growth was observed with Debaryomyces vanrijii and many species of the genus Candida in media with n-hexadecane or wax distillate as sole source of carbon. In addition, some cultures belonging to the genera Sporobolomyces, Hansenula, Cryptococcus, and Trigonopsis could utilize some of these substrates, but to a lesser extent. Highest yield of cells and protein was obtained with Candida lipolytica NRRL 1094 in n-hexadecane medium, supplied with 0.03% yeast extract and trace element solutions. The results are discussed with respect to the possibilities of using new yeast genera, with special reference to the genus Debaryomyces, in microbiol protein production.

Alkanes↗
PubMed1976

Ultrastructure of the ascospores of some species of the Torulaspora group.

Development and germination of the ascospores in species of the Torulaspora group of yeasts have been described. Most species had warty spores which, in sections, showed a dark outer layer consisting of the outer unit membrane of the prospore wall and a layer underneath formed at an early stage of development of the spores. In mature spores the light inner layer of the wall was delimited at the outside by a thin dark layer. The warts often contained dark material. The ascospores of two Pichia and three Debaryomyces species were studied for comparison; they differed in sections from the Torulaspora spores. The taxonomic implications of the ultrastructural observations have been discussed.

Pichia↗
PubMed1975

A critical study of the taxonomic value of some tests of assimilation used for the classification of the sporogenous yeasts.

Six texts of assimilation used in the taxonomy of yeasts, (lactose, maltose, cellobiose, trehalose, melibiose, sucrose) have been critically tested by the examination of intracellular enzymic systems. The results obtained among the sporogenous species of Saccharomyces, Kluyveromyces, Pichia, Hansenula, Debaryomyces indicate that cellobiose, lactose, maltose and trehalose tests no longer supply an important value for the speciation, because the number of cryptical osidases is so high.

Classification↗
PubMedDate not supplied

[Biosynthesis of sterols by various yeasts].

Biosynthesis of sterines by yeasts was studied with 112 strains belonging to 9 genera; 77 strains synthesized ergosterine and 15 most active strains were selected, which belonged to the following genera: Saccharomyces, Torulopsis, Hanseniaspora, Debaryomyces, Candida, Mechnikowia. Sterine composition was studied in these active strains. The main sterine in all studied strains was ergosterine.

Armenia↗