Characteristics of yeasts isolated from phenol- and catechol-adapted activated sludges

Phenol- and catechol-adapted sludges contained large numbers of the yeasts,Candida tropicalis andTrichosporon cutaneum. Both were able to grow on a variety of aromatic compounds and utilized phenol and catechol at a high rate. This property was inducible. The feasibility of using these yeasts for removing phenols from waste waters is suggested.     

Biotransformation of furfural by yeast cells covalently bound to cellulose granules

A 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.     

Isolation and some properties of two extracellular β-glucosidases from Trichosporon adeninovorans

The yeast Trichosporon adeninovorans secretes two multiple forms of β-glucosidase at a high rate if grown in a medium containing cellobiose. Following mutagenesis a mutant strain resistant to 2-deoxy-D-glucose was selected. This strain produced more β-glucosidase activity and had acquired a strong resistance against repression by glucose. The β-glucosidases were separated one from each other by chromatography on hydroxylapatite and by gel filtration. Both enzymes have similar properties. The optimal temperature for their activity was 60 to 63°C and the enzymes displayed highest activity at pH of 4.5. The molecular weight of β-glucosidase I was found to be 570,000 and that for β-glucosidase II was 525,000. The K_m value for cellobiose was determined to be 4.1 mM for β-glucosidase I and 3.0 mM for β-glucosidase II.     

Yeast diversity in a mesotrophic lake on the karstic plateau of Lagoa Santa,MG-Brazil

The yeast diversity in a paleo-karstic lake of the Lagoa Santa plateau was studied during March 1986–March 1987. Water samples were collected monthly at five stations and the yeasts were isolated at 25 °C on Sabourad dextrose agar supplemented with 0.5% of yeast extract and 10 mg% of chloramphenicol. August and February showed the highest numbers of isolates, coinciding, respectively with the beginning and the ending of stratification. Of 56 isolated species, Aureobasidium pullulans, Candida famata, Cryptococcus albidus, Cryptococcus laurentii, Rhodotorula glutinis, Rhodotorula rubra and Trichosporon cutaneum occurred at the highest frequencies. A. pullulans showed greatest prevalence during the dry period (winter), whereas C. famata, Cr. albidus, Cr. laurentii and Rh. rubra were prevalent during the rainy season (summer). Tr. cutaneum was distributed between July and November. Most isolates yeasts are associated with plants and soils, and are important in decomposition of aquatic macrophytes. Furthermore, a possible role of these species as indicators of pollution is discussed.     

Continuous Propagation of Trichosporon cutaneum in Cheese Whey

Trichosporon cutaneum, a nonfermenting yeast, was used to convert cheese whey lactose into microbial cell material. The doubling time for this organism in a laboratory-scale continuous propagator was 2 hr in a whey medium fortified with ammonium sulfate and corn steep liquor. Cellular growth and efficiency of conversion of lactose to cell material was higher than with Saccharomyces fragilis. When grown in whey, the nitrogen content of T. cutaneum was 3.5% and the distribution of amino acids per gram of cell protein was similar to that of commercial food yeasts.     

262 Levaduras del Hombre Aisladas en Caracas,Venezuela

Resumen Se estudian 262 muestras provenientes de uña, ingle, pie, vulvo-vagina, mano, boca, prepucio, oído externo y misceláneos. Se aislan 33 especies diferentes de levaduras, siendoCandida albicans la más común entre ellas con un 41.2 %, seguida deCandida tropicalis, con 16 % yTrichosporon cutaneum con 12.5 %. Dentro de las especies aisladas se encuentran 4 cepas de algasPrototheca sp. (1.5 %).

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From mycological examinations of: nails, groins, feet, vulvo-vagina, hands, mouth, prepuce, external ear, miscelaneous, 262 yeasts strains have been studied. 33 different yeasts species are isolated.Candida albicans was the most frequent with 41.2 %, followed byCandida tropicalis with 16 %, andTrichosporon cutaneum with 12.5 %. The author report 4 strains of algaePrototheca sp. (1.5 %).

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Zusammenfassung 262 Hefestämme sind untersucht worden: von Nägeln, Leistenbeugen, Füssen, Vulvo-vagina, Händen, Munden, Prepucium, Ohren, etc. 33 verschiedene Hefearten sind isoliert worden.Candida albicans war die häufigste mit 41.2 %,C. tropicalis mit 16 %, undTrichosporon cutaneum mit 12.5 %. Vier Stämme von AlgenPrototheca sp. (1.5 %) sind auch gefunden worden.

     

Modification of fatty acid composition of lipid accumulating yeasts with cyclopropene fatty acid desaturase inhibitors

Summary The effect of cyclopropene fatty acids, sterculic and malvalic, on the lipids of yeasts grown under nitrogen limiting, lipid accumulating, conditions was studied. The ratio of stearic to oleic acid showed a dose response effect, with an increase in stearic acid content as the dose of cyclopropene fatty acid increased, and a corresponding reduction in oleic acid. Linoleic and linolenic acids were not affected to the same extent. These effects are shown for the yeasts Candida sp. 107, Trichosporon cutaneum, and Rhodosporidium toruloides.     

Yeasts from U.S.A. soils

Summary Investigations of yeasts from 38 U.S.A. soils samples show the occurrence of 22 different species (16 sporogenous and 6 asporogenous).The most widespread species were Pichia fermentans and Hansenula anomala. The other isolated species were Saccharomyces ellipsoideus, Torulaspora delbrueckii, Pichia membranefaciens, Saccharomyces smittii, Saccharomyces carlsbergensis, Saccharomyces uvarum, Torulaspora rosei, Zygosaccharomyces rouxii, Zygosaccharomyces n. sp., Hansenula saturnus, Hansenula californica, Hansenula n. sp., Hansenula suaveolens, Debaryomyces n. sp., Torulopsis glabrata, Torulopsis n. sp. Candida tropicalis, Candida robusta, Rhodotorula glutinis, Trichosporon cutaneum and Trichosporon cutaneum var. multisporus.     

Yeast-like fungi recovered from normal human skin in Nsukka (Nigeria)

The incidence of yeast-like fungi on normal skin was investigated in 52 healthy Nsukka individuals comprising 21 adults, 24 children, and 7 infants. Eighty-six isolates of yeasts and 2 of Geotrichum candidum were recovered. The yeasts included Candida tropicalis — 36 isolates, C. guilliermondii — 3, C. parapsilosis — 2, Candida spp. (unidentified) — 16, Cryptococcus albidus — 6, Trichosporon cutaneum — 7, Trichosporon spp. — 8 and Rhodotorula spp. — 8 isolates. The isolates originated from various sites, predominantly from nails and finger clefts. The significance of the findings is discussed with particular reference to the absence of C. albicans and the frequent isolation of C. tropicalis, T. cutaneum and C. albidus.     

Oxidation of amines by yeasts grown on 1-aminoalkanes or putrescine as the sole source of carbon,nitrogen and energy

The maximum growth rate of Trichosporon cutaneum CBS 8111 in chemostat cultures was 0.185 h^-1 on ethylamine and 0.21 h^-1 on butylamine, that of Candida famata CBS 8109 was 0.32 h^-1 on putrescine.The amine oxidation pattern of the ascomycetous strains studied, viz. Candida famata CBS 8109, Stephanoascus ciferrii CBS 4856 and Trichosporon adeninovorans CBS 8244 was independent of the amine that had been used as the growth substrate. It resembled that of benzylamine/putrescine oxidase found in other ascomycetous yeasts. However, differences in pH optimum and substrate specificity were observed between the amine-oxidizing systems of these three species.The amine oxidation pattern of cell-free extracts of Trichosporon cutaneum CBS 8111 varied with the amine that was used as growth substrate. The enzyme system produced by Cryptococcus laurentii CBS 7140 failed to oxidize isobutylamine and benzylamine, and showed a high pH optimum.The synthesis of amine oxidase in the four yeast strains studied was not repressed by ammonium chloride and was weakly repressed by glucose but was strongly repressed if both compounds were present in the growth medium.     

Inhibitory effect of lignin by-products of pulping on yeast growth

The antimicrobial properties of lignin by-products obtained by organic solvent, neutral sulfite semichemical and kraft pulping were shown in a series of yeasts. Lignin can act as an inhibitor of growth ofSporobolomyces roseus, Candida tropicalis, Trichosporon cutaneum andCandida albicans. Oxidation of all lignin samples tested depresses their inhibitory effects.     

Les levures dans les eaux de la Moselle

We have identified 95 yeast species, in the river Moselle. Trichosporon cutaneum is a very good indicator for pollution caused by men and disappears rapidly in the zone of recovery. In not polluted water, the white yeasts are absent or nearly so, and only red pigmented yeasts are present. Sporobolomyces odorus is always present in these fractions. From the source till the border (Thionville) an increasing percentage of red yeasts present in the water is an indicator for a recovery of the river after heavy pollution.

     

Production of single-cell protein from enzymatic hydrolyzate of rice straw

Summary The components of rice straw, pretreated with sodium chlorite, cellulose and hemicellulose were solubilized with culture filtrate of Pellicularia filamentosa or Trichoderma reesei. The ratio of glucose to total sugar in the solution obtained from the cellulose component with the culture filtrate of Pellicularia filamentosa was approximately twice that of Trichoderma reesei.Ten yeast strains (Candida utilis, C. tropicalis, C. guilliermondii, C. parapsilosis, Torulopsis xylinus, Trichosporon cutaneum, Debaryomyces hansenii, Rhodotorula glutinis, Saccharomyces fragilis and Saccharomyces cerevisiae) were cultivated as test organisms for single-cell protein (SCP) production on sugar solutions obtained from the straw, cellulose and hemicellulose components, pretreated with the culture filtrate of Pellicularia filamentosa. Sugar consumption, in terms of total sugar and cell yield, of the culture with the sugar solution obtained from pretreated straw were; 70% and 6.8 g/l for Candida tropicalis, 56% and 6.4 g/l for Torulopsis xylinus, 76% and 10.1 g/l for Trichosporon cutaneum, and 74% and 7.6 g/l for Candida guilliermondii. In addition, the highest consumption with respect to total sugar (87%) and the best dry cell yield (15.6 g/l) were observed with the culture of Trichosporon cutaneum using the sugar solution obtained from the hemicellulose component.     

β-Glucosidase production by Trichoderma reesei QM9414 on wheat straw. Location and some kinetic features

In this paper we studied the conditions for the production of β-glucosidase from T. reesei QM9414 in batch cultures using milled and sieved wheat straw as sole carbon source. High β-glucosidase production in the presence of wheat straw, a more realistic substrate than commercial cellulose, was obtained. The influence of particle size of wheat straw on β-glucosidase production in cell-free, cell and cell-wall extracts was studied. The particle size of wheat straw notably influenced enzyme production in cell and extramycelial extracts but it was less important with respect to the cell wall bound enzyme. β-glucosidase production was studied along of the fermentation. The results suggest a close relation between β-glucosidase from cell extract and extramycelial broth; geneticin levels of inhibition of β-glucosidase biosynthesis in both fractions were similar, a fact that suggests a common origin for the enzyme. Kinetic parameters for β-glucosidase from cell free and cell extracts were V_max = 0.28 μmol/min/mg, K_M = 0.91 mM and V_max = 0.095 μmol/min/mg, K_M = 0.39 mM respectively. Kinetic parameters for β-glucosidase from cell-wall could not be calculated because experimental data did not fit the different monosubstrate equations.     

Growth of Candida famata and Trichosporon cutaneum on uric acid as the sole source of carbon and energy,a hitherto unknown property of yeasts

Yeast strains capable of utilizing uric acid as the sole source of carbon and energy were isolated from soil by the enrichment culture method. The strains were identified as Candida famata (Harrison) Meyer et Yarrow and Trichosporon cutaneum (De Beurm., Gougerot et Vaucher) Ota. On the subcellular level growth of yeasts on uric acid was accompanied with the development of a number of large microbodies in the cells.     

Lumping kinetics of ABE fermentation wastewater treatment by oleaginous yeast Trichosporon cutaneum

Lumping kinetics models were built for the biological treatment of acetone–butanol–ethanol (ABE) fermentation wastewater by oleaginous yeast Trichosporon cutaneum with different fermentation temperatures. Compared with high temperature (33°C, 306?K) and low temperature (23°C, 296?K), medium temperature (28°C, 301?K) was beneficial for the cell growth and chemical oxygen demand (COD) degradation during the early stage of fermentation but the final yeast biomass and COD removal were influenced little. By lumping method, the materials in the bioconversion network were divided into five lumps (COD, lipid, polysaccharide, other intracellular products, other extracellular products), and the nine rate constants (k₁–k₉) for the models can well explain the bioconversion laws. The Gibbs free energy (G) for this bioconversion was positive, showing that it cannot happen spontaneous, but the existence of yeast can after the chemical equilibrium and make the bioconversion to be possible. Overall, the possibility of using lumping kinetics for elucidating the laws of materials conversion in the biological treatment of ABE fermentation wastewater by T. cutaneum has been initially proved and this method has great potential for further application.     

Association of anurans with pathogenic fungi

In a study of 450 Amazonian anurans, we isolated yeasts and yeast-like fungi from 54 animals (Bufo granulosus, B. marinus, Dendrophrynyscus sp., Hyla geographica, H. lanciformes, Ololygon rubra, Adenomera hylaedactyla, Eleutherodactylus fenestratus, Leptodactylus fuscus, L. ocellatus, L. pentadactylus). The internal organs of these animals did not show any macroscopic anomaly nor histopathology. We recovered 105 fungal isolates from the anuran liver, lung, kidney, spleen, heart and gonad. The isolates were made up of 30 fungal species, 9 of which (48 isolates, 46%) were fungi with known pathogenic potentials, namely: Candida guilliermondii, C. parapsilosis, C. tropicalis, C. glabrata, Geotrichum candidum, Aureobasidium pullulans, Wangiella dermatitidis, Trichosporon cutaneum and Exophiala werneckii. Eleven animals harbored identical fungi in more than one of their internal organs; seven animals had more than one fungal species colonizing a single organ. Our findings indicated probable natural subclinical infections of candidiasis, geotrichosis or phaeohyphomycosis, and also symbiotic presence of non-pathogenic fungi among neotropical anurans.     

Use of elephant grass (Pennisetum purpureum) acid hydrolysate for microbial oil production by Trichosporon cutaneum

Elephant grass (Pennisetum purpureum) dilute acid hydrolysate contains 34.6?g/L total sugars. The potential of lipid production by oleaginous yeast Trichosporon cutaneum grown on elephant grass acid hydrolysate was investigated for the first time. During the fermentation process on the elephant grass acid hydrolysate, glucose, xylose, and arabinose could be well utilized as carbon sources by T. cutaneum. Interestingly, xylose was almost no use before glucose was consumed completely. This illustrated that simultaneous saccharification of xylose and glucose by T. cutaneum did not occur on elephant grass acid hydrolysate. The highest biomass, lipid content, lipid yield, and lipid coefficient of T. cutaneum were measured after the sixth day of fermentation and were 22.76?g/L, 24.0%, 5.46?g/L, and 16.1%, respectively. Therefore, elephant grass is a promising raw material for microbial oil production by T. cutaneum.     

The bgl1 gene of Trichoderma reesei QM 9414 encodes an extracellular, cellulose-inducible β-glucosidase involved in cellulase induction by sophorose

We have investigated the effect of disruption of the bgl1-(β-glucosidase l-encoding) gene of Trichoderma reesei on the formation of other β-glucosidase activities and on the induction of cellulases. To this end the bgl1 locus was disrupted by insertion of the Aspergillus nidulans amdS (acetamidase-encoding) gene. The bgl1-disrupted strain did not produce the 75kDa extracellular β-glucosidase on cellulose or lactose, but still formed β-glucosidase activity on glucose, cellobiose, xylan or β-1,3-glucan, suggesting that the enzyme(s) exhibiting this β-glucosidase activity is (are) not encoded by bgl1. The cellulose-inducer sophorose induced the bgl1-encoded β-glucosidase, whereas the remaining β-glucosidase activity was induced by methyl-β-D-glucoside. The bgl1-gene product was mainly secreted into the medium, whereas the other β-glucosidase activity was mainly associated with the cells. A bgl1-multicopy strain formed higher amounts of cellulases than the parent strain. Nonsaturating concentrations of sophorose efficiently induced cellobiohydrolase I formation in the bgl1-multicopy strain, but less efficiently in the bgl1-disrupted strain. The multicopy strain and the parent strain were comparably efficient at saturating sophorose concentrations. The β-glucosidase inhibitor nojirimycin strongly inhibited induction in all strains. These data suggest that the bgl1-encoded β-glucosidase is not identical to the plasma-membrane-bound, constitutive, methyl-β-glucoside inducible β-glucosidase, but represents an extracellular cellulose-induced enzyme. Both enzymes contribute to rapid induction of cellulases by modifying the inducer sophorose.     

Identification and characterisation of xylanolytic yeasts isolated from decaying wood and sugarcane bagasse in Brazil

In this study, yeasts associated with lignocellulosic materials in Brazil, including decaying wood and sugarcane bagasse, were isolated, and their ability to produce xylanolytic enzymes was investigated. A total of 358 yeast isolates were obtained, with 198 strains isolated from decaying wood and 160 strains isolated from decaying sugarcane bagasse samples. Seventy-five isolates possessed xylanase activity in solid medium and were identified as belonging to nine species: Candida intermedia, C. tropicalis, Meyerozyma guilliermondii, Scheffersomyces shehatae, Sugiyamaella smithiae, Cryptococcus diffluens, Cr. heveanensis, Cr. laurentii and Trichosporon mycotoxinivorans. Twenty-one isolates were further screened for total xylanase activity in liquid medium with xylan, and five xylanolytic yeasts were selected for further characterization, which included quantitative analysis of growth in xylan and xylose and xylanase and β-d-xylosidase activities. The yeasts showing the highest growth rate and cell density in xylan, Cr. laurentii UFMG-HB-48, Su. smithiae UFMG-HM-80.1 and Sc. shehatae UFMG-HM-9.1a, were, simultaneously, those exhibiting higher xylanase activity. Xylan induced the highest level of (extracellular) xylanase activity in Cr. laurentii UFMG-HB-48 and the highest level of (intracellular, extracellular and membrane-associated) β-d-xylosidase activity in Su. smithiae UFMG-HM-80.1. Also, significant β-d-xylosidase levels were detected in xylan-induced cultures of Cr. laurentii UFMG-HB-48 and Sc. shehatae UFMG-HM-9.1a, mainly in extracellular and intracellular spaces, respectively. Under xylose induction, Cr. laurentii UFMG-HB-48 showed the highest intracellular β-d-xylosidase activity among all the yeast tested. C. tropicalis UFMG-HB 93a showed its higher (intracellular) β-d-xylosidase activity under xylose induction and higher at 30 °C than at 50 °C. This study revealed different xylanolytic abilities and strategies in yeasts to metabolise xylan and/or its hydrolysis products (xylo-oligosaccharides and xylose). Xylanolytic yeasts are able to secrete xylanolytic enzymes mainly when induced by xylan and present different strategies (intra- and/or extracellular hydrolysis) for the metabolism of xylo-oligosaccharides. Some of the unique xylanolytic traits identified here should be further explored for their applicability in specific biotechnological processes.