Candida Tropicalis Strains Research Articles

Changes in membrane electrical parameters of yeast following chemical treatment for protoplast isolation

The yeast strains Saccharomyces species and Candida tropicalis were used. In each case, the electrorotation spectra were recorded for normal untreated yeast cells, β-mercaptoethanol-treated cells and isolated protoplasts. In order to obtain realistic information on the passive electrical membrane parameters associated with each step of protoplast isolation, a theoretical analysis of the simulated electrorotation spectra for shelled ellipsoids was performed. As a consequence, the parameters chosen for fitting of the experimental spectra were the electrical conductivities of the cell compartments, the membrane permittivity and the scaling factor. β-Mercaptoethanol was found to have significant action at the membrane level: (1) at high concentration (2%), σ m was increased dramatically; (2) in mild incubation conditions (0.1%), σ m was decreased slightly. Treatment with the enzyme complex led to a decrease in internal conductivity, probably due to a loss of the ionic equilibrium balance.

The effect of sodium hypochlorite on potential pathogenic traits of Candida albicans and other Candida species.

Strains of Candida albicans, Candida krusei, Candida kefyr, Candida tropicalis, Candida parapsilosis and Candida guilliermondii were grown in the presence or absence of concentrations of sodium hypochlorite below the minimal inhibitory concentration and tested for a range of characteristics that may be associated with pathogenicity. Sodium hypochlorite is used routinely in hospitals in Australia for disinfection procedures, and these experiments were designed to assess the efficacy of hypochlorite as a sterilizing agent for acrylic dentures. Candida showed varying abilities to adhere to surfaces that may be present in the oral cavity. Sodium hypochlorite reduced the adhesion of all C. albicans strains and most other Candida species to both polystyrene and buccal epithelial cells. A biofilm of Streptococcus gordonii reduced the adhesion of most C. albicans strains and most other Candida species to polystyrene. However, Candida species were able to coaggregate with S. gordonii in suspension, with one strain of C. albicans, GDH 2346, showing greater coaggregating ability than the other strains or species. Sodium hypochlorite increased coaggregation of all C. albicans strains and most other Candida species. Examination of cell wall proteins from strains of C. albicans and a strain of C. parapsilosis showed that growth in hypochlorite increased the amount of protein in some existing bands and, in one strain of C. albicans, increased the number of detectable protein bands ranging from 56 to 26 kDa. Only 4 strains of C. albicans were able to produce hyphae, and 3 of these same strains and C. parapsilosis were able to produce proteinase. Hypochlorite increased the rate of blastospore to hyphal transition but had no effect on proteinase production or activity. It is concluded that hypochlorite at a concentration below the minimal inhibitory concentration may function as an anti-adhesin for Candida species but may not affect their more pathogenic characteristics.

A Synthesis of (Z)-Octadec-9-enedioic Acid

The monomethyl ester of azelaic acid was transformed into two fragments, namely [8-( methoxy -carbonyl) octyl ] triphenylphosphonium bromide and methyl 9-oxononanoate. A Wittig reaction between these two fragments produced dimethyl (Z)-octadec-9-enedioate and subsequent hydrolysis gave the title diacid. Interestingly, the same diacid was available directly from oleic acid in a published procedure which utilized a mutant strain of Candida tropicalis.

Pathogenicity of yeasts and algae isolated from bovine mastitis secretions in a murine model.

The pathogenicity of strains of yeasts and algae isolated from bovine mastitis secretions was evaluated in immunosuppressed mice. Strains of Candida tropicalis (n = 3) were the most pathogenic, but all strains of Geotrichum capitatum (n = 5) and the colourless alga Prototheca zopfii (n = 5) were also lethal to mice at the highest dose of 1 x 10(7) CFU per mouse. Reisolation of the inoculated micro-organisms and the occurrence of histopathological lesions within organs of mice challenged with 1 x 10(3) to 1 x 10(7) CFU per animal revealed strains of C. krusei (n = 17), C. kefyr (n = 6) and C. rugosa (n = 6) to have a moderate pathogenicity, whereas strains of C. valida (n = 1) and C. catenulata (n = 2) were weakly pathogenic and non-pathogenic respectively.

Structures of cell wall mannans of pathogenic Candida tropicalis IFO 0199 and IFO 1647 yeast strains

We conducted a structural analysis of the cell wall mannans isolated from two Candida tropicalis strains, IFO 0199 and IFO 1647, exhibiting strong agglutinabilities against anti-Candida factor sera 5 and 6. The products released from these mannans by acid treatment were identified as the oligosaccharides, from biose to pentaose, consisting solely of beta-1,2-linked mannopyranose units corresponding to common epitopes of Candida albicans serotypes A and B (factor 5). Mild acetolysis of acid- and alkali-treated mannans produced large amounts of hexaose and heptaose, Man rho beta 1-2Man rho beta 1-2Man rho alpha 1-2Man rho alpha 1-2Man rho alpha 1-2Man and Man rho beta 1-2Man rho beta 1-2Man rho beta 1-2Man rho alpha 1-2 Man rho alpha 1-2Man, corresponding to the C. albicans serotype A-specific epitopes (factor 6). However, the homologous pentaose, Man rho beta 1-2Man rho alpha 1-2 Man, was not generated by this procedure. The oligosaccharides (biose to hexaose) obtained from the mannans by conventional acetolysis were composed exclusively of alpha-1,2-linked mannopyranose units. Therefore, the mannans of C. tropicalis IFO 0199 and IFO 1647 do not have the alpha-1,3-linked mannopyranose units previously observed in the mannans of C. albicans and Candida stellatoidea. The results of this study and previous findings indicate that the similarity of the antigenicities of three Candida species, C. albicans serotype A, C. stellatoidea type II, and C. tropicalis, reside in the beta-1,2 and alpha-1,2 linkages containing oligomannosyl side chain (factor 6) in the cell wall mannan.

Biotransformation of furfural by yeast cells covalently bound to cellulose granules

AbstractA covalent binding to cellulose granules of two yeast strains Candida tropicalis and Trichosporon cutaneum was achieved. The maximum activity for destroying furfural by the immobilized cells was obtained when the procedure conditions were: reaction medium at pH 5.0, 20°C and cell suspension concentration of 80 mg/ml. The continuous furfural transformation was studied using a growth medium in a fermenter with immobilized Trichosporon cutaneum in which a 84% bioconversion was achieved. The reduced values of furfural remained constant even after 10‐fold transformation.

Purification and characterization of secretory proteinase of Candida albicans.

Proteolytic activity of medically important yeasts was tested in both YCB-BSA agar and medium. All of 134 strains of Candida albicans, 13 of 18 strains of Candida tropicalis and 11 of 18 strains of Candida parapsilosis had this activity, while none of 52 Candida glabrata strains or of 11 Cryptococcus neoformans strains tested had proteolytic activity. Strains of C. albicans fell into five groups based on the level and time-course of in vitro proteinase productivity. Five strains randomly selected from each group were tested for pathogenicity in mice. The strain possessing the strongest pathogenicity was used to purify proteinase. The molecular weight of the proteinase was approximately 44,000 daltons and its isoelectric point was pH 4.2. Optimal pH of the proteinase was 3.2 and the enzyme was stable below pH 7.0 and lost its activity above pH 8.0 at 37 C in a 60-min incubation. The 23 amino acid sequence of the proteinase N-terminus was determined.

Interspecific protoplast fusion between Candida tropicalis and Candida boidinii: Characterization of the fusants

The polyethylene glycol (PEG) and electroporation protoplast fusion methods were applied to imperfect yeasts of the genus Candida to induce interspecific fusion. Auxotrophic strains of Candida tropicalis (an n-alkane-utilizing yeast) and Candida boidinii (a methanol-utilizing yeast) were used as parental strains and fusion products were selected by complementation on minimal medium. The frequency of fusion induced by filter-sterilized PEG was high, ranging from 10 −4 to 10 −5. Scanning electron microscopy showed that the fusants varied considerably in shape, surface structure, and cell volume. Various electrophoretic karyotypes of fusants were observed, although their karyotypes were basically the same as that of C. boidinii. Morphological, biochemical, and physiological studies indicated that the characteristics of the fusants were mainly those of C. boidinii, but with some of those of C. tropicalis. The fusants could utilize methanol and n-alkane as sole carbon sources when they were first isolated, but their ability to utilize n-alkane was lost during their prolonged storage.

Substrate inhibition of phenol oxidation by a strain ofCandida tropicalis

The kinetics for growth on phenol by a yeast identified asCandida tropicalis was investigated in batch culture and by respirometry. The culture was tolerant of an initial phenol concentration of up to 1.5 g/l. The optimum temperature for phenol oxidation was 32°C and below this the Arrhenius relationship was obeyed. A Michaelis Menten relationship described the substrate inhibition of theCandida by phenol.

Nitrogenase activity of diazotrophic strains ofCandida tropicalis

Nitrogenase activity of 4 strains ofCandida tropicalis exhibited a pH optimum of 7·2 and an optimum temperature of 30°C; it was depressed by NH4+ ions and at 1 mM no activity could be detected. 2,4-Dinitrophenol, sodium azide andp-chlormercuribenzoate abolished nitrogenase activity completely at 2·5×10−4 M. Nitrogenase activity was increasingly inhibited by O2 with increasing concentrations; it was also inhibited by methane and methanol. The yeast cells possessed active uptake hydrogenase activity.

Nitrogen fixation byCandida tropicalis

Several strains ofCandida tropicalis isolated from the dung of buffalo, cow and goat have been found to fix N2. The nitrogenase activity (acetylene reduction) varied between 73 and 1162 nmol (mg protein)−1 h−1. 2·2–9·3 mg N2 were fixed g−1 glucose consumed. Acetylene was reduced progressively with time. Acetylene reduction could not be observed in cells treated with cycloheximide but was unaffected by antibiotics which inhibit the growth of prokaryotes.

Production of bioemulsifier by a SCP-producing strain ofCandida tropicalis during hydrocarbon fermentation

SCP producingCandida tropicalis, when grown in fed batch culture using n-hexadecane as carbon substrate, exhibited extracellular emulsifier production. The emulsifier showed activity against various hydrocarbons, maximum with aromatics and least with normal paraffins. Higher emulsification activity was noted in nitrogen-limiting growth conditions than in substrate- limiting conditions. The hot water extract of the cells also showed significant emulsification activity.

Discriminant analysis of cellular fatty acids of Candida species, Torulopsis glabrata, and Cryptococcus neoformans determined by gas-liquid chromatography

We used discriminant analysis of cellular fatty acid compositions determined by gas-liquid chromatography to differentiate yeastlike fungi (a total of 190 strains; including 37 Candida albicans strains, 21 Candida krusei strains, 13 Candida guilliermondii strains, 37 Candida tropicalis strains, 10 Candida pseudotropicalis strains, 24 Candida parapsilosis strains, 32 Torulopsis glabrata strains, and 16 Cryptococcus neoformans strains). Previous results with a standard strain of C. albicans indicated that reproducible fatty acid chromatograms can be obtained with cells grown in a medium of 2% Sabouraud glucose agar at 35 degrees C for between 48 and 72 h. These conditions were also maintained in cultures of the other organisms that we studied. The cellular fatty acid compositions of the organisms were determined quantitatively by gas-liquid chromatography and analyzed by discriminant analysis. The total correct identification expressed as relative peak percent was 95.8% (89.2% for C. albicans to 100% for C. krusei, C. guilliermondii, C. pseudotropicalis, T. glabrata, and C. neoformans). The total correct identification expressed as the common peak (palmitic acid) ratio was 94.7% (87.5% for C. parapsilosis to 100% for C. pseudotropicalis, T. glabrata, and C. neoformans). Both results suggest that cellular fatty acid compositions can be differentiated by this method.

The spermicidal compound nonoxynol-9 increases adhesion of Candida species to human epithelial cells in vitro

All 25 strains of Candida spp. tested were able to grow in medium supplemented with 25% nonoxynol-9 in vitro. Adhesion of Candida spp. to HeLa cells was found to increase in the presence of 5% nonoxynol-9 (2.2- to 6.6-fold; P less than 0.001) and, to a lesser extent, in 12.5% nonoxynol-9. Adhesion of Candida strains cultured in medium supplemented with nonoxynol-9 varied, with five of six strains of Candida albicans and the single strain of Candida tropicalis demonstrating increases of 1.4 to 4.0 times control levels (P less than 0.05). The increased adhesion did not correlate with altered yeast cell surface hydrophobicity or germ tube formation.

Collaborative evaluation in seven laboratories of a standardized micromethod for yeast susceptibility testing.

The new micromethod for yeast susceptibility testing, MYCOTOTAL, was evaluated with 10 reference strains in seven laboratories. Ready-to-use microtitration plates and the same synthetic medium were used with two dilutions of imidazoles, flucytosine, and amphotericin B, permitting the categorization of each strain as susceptible, intermediate, or resistant. The results were compared with the MIC for each reference strain, and the repeatability and reproducibility were evaluated. The yeasts tested presenting different patterns of susceptibilities in reference MICs included six strains of Candida albicans, two strains of Candida tropicalis, one strain of Candida parapsilosis, and one strain of Torulopsis glabrata. For 4,200 antifungal agent-yeast results, the repeatability was 99.3% and the reproducibility was 96.3%. The correlation between the reference MICs and the category results was 91.5% for seven laboratories (and 92.7% for six laboratories excluding the laboratory which did not follow exactly the same protocol). We observed only 7.9% minor discrepancies, 0.5% (0.29% for six laboratories) major discrepancies, and 0.1% uninterpretable results. The percentages of concording results were similar for each strain and each antifungal agent tested. The overall results indicated that MYCOTOTAL was a reliable and reproducible method, well correlated with reference MICs. This ready-to-use micromethod with the same medium for all antifungal agents would be an important step in the necessary standardization of yeast susceptibility testing.

Endothelial cell contraction increases Candida adherence to exposed extracellular matrix.

Bovine vascular endothelial cells treated with EDTA, urea, or thrombin underwent a marked, reversible contraction resulting in exposure of the subendothelial extracellular matrix (ECM). Candida yeasts adhered more to contracted monolayers than to confluent monolayers (P less than 0.01) by preferentially adhering to the ECM. Two strains of Candida albicans and one strain of Candida tropicalis bound avidly to exposed ECM, but Pseudomonas aeruginosa did not. However, treatment of endothelium with forskolin, which induces cell shape changes without exposure of the ECM, did not cause an increase in adherence.

Fermentation of kraft black liquor for the production of citric acid by Candida tropicalis

The production of citric acid by batch fermentation with the yeast strain Candida tropicalis ATCC 20240 was chosen as a potential process for the valorization of kraft black liquor. The effect of nitrogen concentration was studied and direct bioconversion of acetate to citrate was achieved when no nitrogen was supplemented to the medium. The use of kraft black liquor's acetate as a potential substrate for citric acid production was investigated. The acid precipitated liquor was highly inhibitory when its concentration was above 25% of the fermentation broth content. The yields of citric acid at low concentrations of kraft black liquor (5% and 15%) were the same as those recorded in synthetic acetate medium. Other organic acids present in the liquor may affect the yields and rates of citric acid production over acetate. Substrate uptake rates and product formation rates were lower, however, in comparison to synthetic media. The utilization of immobilized biomass improved the process parameters on kraft black liquor and enhanced the fermentation capabilities.

Antigenic differences in the surface mannoproteins of Candida albicans as revealed by monoclonal antibodies

Monoclonal antibodies to Candida albicans were prepared with blastoconidia bearing germ tubes used as the immunogen. Four antibodies reacted by immunofluorescence with surfaces of C. albicans as well as Candida stellatoidea, Candida tropicalis, and several strains of C. albicans, but not with Torulopsis glabrata. One antibody reacted with Saccharomyces cerevisiae. In addition, the monoclonal antibodies precipitated material of approximately 200 kilodaltons when tested against metabolically labeled blastoconidia digests. The monoclonal antibodies exhibited heterogeneous staining of C. albicans surfaces, as shown by immunofluorescence. None of the monoclonal antibodies were specific to germ tubes. More importantly, however, two of the monoclonal antibodies reacted with the mannoprotein precipitin arc of C. albicans that was produced by reference rabbit polyclonal antisera by crossed immunoelectrophoresis, thus linking the heterogeneity seen by immunofluorescence to the heterogeneity in mannoproteins. Finally, three of the monoclonal antibodies reacted with a glycan fraction of cell digests, indicating their reactivity with the carbohydrate portion of the mannoprotein.

Abbau von Phenol durch Hefen in Gegenwart von n-Hexadekan unter Wachstumsbedingungen im Rührreaktor

Summary Phenol degradation by various strains of Candida maltosa and other yeasts was investigated in the presence and absence of n-hexadecane in a stirred reactor. The 3 strains of Candida maltosa (L4, T 420, CBS 5611) and Candida tropicalis T 431 B degradate 0.5 g/l phenol within 5 to 8 h under our test conditions, whereas it takes Trichosporon cutaneuni 27 about 85 h. In the presence of n-hexadecane degradation of phenol by Candida maltosa L4 is delayed due to repression of the synthesis of phenol hydroxylase and catechol-1.2-oxygenase. For Candida maltosa T 420 and CBS 5611 it is only weakly delayed and for Candida tropicalis T 431 B and Trichosporon cutaneum 27 nearly or completely not at all. This is the first report on a metabolic repression by n-alkanes. Results are discussed with consideration of a possible employment of Candida maltosa for biological treatment of phenol containing effluents.

Noninvasive and quantitative 19F nuclear magnetic resonance study of flucytosine metabolism in Candida strains.

19F nuclear magnetic resonance was used for a noninvasive and quantitative study of flucytosine (FC; 5-fluorocytosine) metabolism in two strains of Candida albicans and one strain of Candida tropicalis with various susceptibilities to FC. Three intracellular fluorinated metabolites were detected in the highly susceptible strain, F-nucleotides (Fnt), F-nucleosides, and 5-fluorouracil (5FU). Fnt were partially converted into 5FU when the spectra of the yeasts were recorded at 37 degrees C without perfusion, but the intensities of the signals were not modified at 4 or 37 degrees C if the cells were perfused. In the acid extract, the Fnt signal was resolved into three distinct peaks; none of them was attributable to 5-fluoro-2'-deoxyuridine-5'-monophosphate. The same signals were detected in the partially resistant strain, but only 5FU was observed in the highly resistant strain; the resistance of the latter strain therefore was primarily due to a defect in UMP pyrophosphorylase. At the end of the incubation period, only FC and released 5FU were present in the culture media. The concentration of the intracellular fluorinated metabolites was increased if the strain was susceptible to FC. The total amount of metabolized FC was very similar for the highly susceptible and the partially resistant strains, but the percentage of Fnt was much higher in the former (38%) than in the latter (8%); the mild resistance of the partially resistant strain therefore was attributed to the decreased activity of UMP pyrophosphorylase.