Four new species of yeast isolated from insect frass in bark ofTsuga heterophylla (Raf.) Sargent

Summary In a study of the yeasts associated with insect frass underneath the bark ofTsuga heterophylla (the Pacific Coast hemlock) four new species of yeast were found. These were described asSporobolomyces singularis, Bullera tsugae, Cryptococcus skinneri andCandida oregonensis. Sporobolomyces singularis is a non-pigmented species, which required an amendment of the genus definition. Ballistospore formation of the new species ofSporobolomyces and ofBullera was absent on malt agar and on potato glucose agar, but positive on corn meal agar. An unusual case of quantitative transgalactosylation by growing cells ofSporobolomyces singularis on lactose has been described. It has been proposed to establish a “Candida parapsilosis Group” of species to whichC. oregonensis was assigned. Supported by a fellowship of the Calouste Gulbenkian Foundation, Lisbon, Portugal.     

Sporobolomyces yuccicola,a new species of ballistosporous yeast equipped with ubiquinone-9

A hitherto undescribed ballistosporous yeast was isolated from a dead leaf of Yucca sp. in Canada. This yeast produces apiculate or short-ellipsoidal ballistospores, produces pale colored colonies, has Q-9 as the major ubiquinone, and does not contain xylose in the cells. This new yeast is described as Sporobolomyces yuccicola Nakase et Suzuki. Sporobolomyces yuccicola is the sixth species of the intermedius group, a group of atypical species of the genus Sporobolomyces equipped with Q-9.     

Sporobolomyces salmonicolor var. fischerii,a new yeast

A new variety of Sporobolomyces salmonicolor, a basidiomycetous yeast isolated from the cerebrospinal fluid of a human case of meningitis has been described. The variety can be differentiated from the species primarily by its ability to assimilate D-galactose and L-arabinose.     

Ballistosporous yeasts found on the surface of plant materials collected in New Zealand

Six new species of ballistosporous yeast, the genusSporobolomyces, were isolated from dead leaves and fruit of plants collected in New Zealand;Sp. novazealandicus, Sp. dimmenae, Sp. coprosmicola, Sp. coprosmae, Sp. dracophyllus, andSp. taupoensis. These species differ from any hitherto known species ofSporobolomyces based on chemotaxonomic characteristics.Abbreviations B. Bullera - Ben. Bensingtonia - Sp. Sporobolomyces - Sporid. Sporidiobolus - T. Tilletiopsis - U. Udeniomyces - G + C guanine plus cytosine     

A novel process for the production of high-purity galactooligosaccharides (GOS) using consortium of microbes

Galactooligosaccharides (GOS) are nondigestible dietary fibers which have a beneficial effect on human health by promoting the growth of probiotic bacteria in the gut. In addition, other health benefits have been reported from oligosaccharides consumption such as stimulation of intestinal mobility, colon cancer prevention, mineral absorption as well as protection against certain pathogenic bacterial infections. The goal of this research was to develop an efficient biotransformation system using a consortium of microbes for the production of ≥85% pure GOS and reusing the cell biomass in repeated cycles of biotransformation. Production of GOS by lactose transgalactosylation using whole cells of Sporobolomyces singularis MTCC 5491 as a source of β-galactosidase and monosaccharides utilization by yeast isolate (NUTIDY007) were studied. For increasing the purity of GOS, growth and bioconversion parameters on the transgalactosylation by the whole cells were investigated. Further, continuous production of GOS was studied in a reactor with microfiltration membrane system. A maximum GOS purity of 42% was achieved using single culture of S. singularis. Under optimized conditions, single culture of S. singularis produced a maximum of 56% pure GOS. Addition of second culture to the reaction mixture for utilization of glucose significantly increased the GOS purity from 56% to ≥85%. The product consisted of tri- to penta-galactooligosaccharides. Trisaccharides were the main component of the reaction mixture. A maximum productivity of 10.9?g/L/hr was obtained under the optimum conditions.     

Seasonal Dynamics in a Yeast Population on Leaves of the Common Wood Sorrel Oxalis acetosella L.

Analysis of an epiphytic yeast population on the leaves of the evergreen common wood sorrel Oxalis acetosella L. throughout a year showed that the density and the species composition of this population underwent regular seasonal changes. There were almost no yeasts on the young spring leaves. However, the yeast population on the mature leaves tended to increase in the autumn, reaching a maximum after the formation of continuous snow cover. Then the yeast population on the leaves tended to decrease, reaching a minimum in the spring. The species diversity of the yeasts was maximum in the autumn. The population of the epiphytic yeast species Cystofilobasidium capitatum, Rhodotorula fujisanensis, Leucosporium scottii, and Cryptococcus flavus peaked in the autumn. On the other hand, the population of the widespread epiphytic species Cryptococcus laurentii on the wood sorrel leaves peaked in January. The relative abundance of the red-pigmented phytobionts Rhodotorula glutinis and Sporobolomyces roseus virtually did not change throughout the year. The relative abundance of the euribiotic species Cryptococcus albidus showed irregular monthly variations. The data obtained show that the epiphytic microbial population of various plants can be comprehensively studied only by analyzing this population throughout the vegetative period of the plants.     

Molecular and morphological examination of Cyrtobagous sp. collected from Argentina, Paraguay, Brazil, Australia, and Florida

Two members of the floating fern genus Salvinia (Salviniaceae), S. minima Baker and S. molesta Mitchell, have established in the United States. Cyrtobagous salviniae Calder and Sands (Coleoptera: Curculionidae), long established on Florida S. minima, was released in Texas and Louisiana as a biocontrol agent for both species. Subsequently, sequence analysis of the 28S rRNA D2 expansion domain suggested that the Florida and Brazilian populations (used worldwide for biocontrol) of C. salviniae might constitute two cryptic species. In response, the Brazilian weevil was imported from Australia and released instead onto S. molesta. We sampled C. singularis Hustache and C. salviniae from their native ranges in Brazil, Argentina, and Paraguay and sequenced them (D2) along with Australian and Florida samples. The genetic distance between C. singularis and C. salviniae samples is much greater (almost 5×) than the distance between either the Florida and Brazilian samples or the Brazilian and Argentinean/ Paraguayan C. salviniae samples. Since C. singularis and C. salviniae are cryptic species, the Florida and Brazilian populations (or for that matter Brazilian and Argentinean/Paraguayan) could reasonably be described as demes or ecotypes. Occurrence data indicates that, in parts of their ranges, C. salviniae and C. singularis are not only sympatric but also feed on the same plant species at the same site. While host adaptation (species preferences) likely occurs within local demes, both species seem capable of adapting to the available resource (Salvinia species). Finally, a polymerase chain reaction (PCR) primer was developed to distinguish the Florida and Brazilian/Australian types.     

Yeast Diversity in Hydromorphic Soils with Reference to a Grass–Sphagnum Wetland in Western Siberia and a Hummocky Tundra Region at Cape Barrow (Alaska)

The microbiological analysis of 78 samples taken from a high bog in Western Siberia and from a tundra wetland soil in Alaska showed the presence of 23 yeast species belonging to the genera Bullera, Candida, Cryptococcus, Debaryomyces, Hanseniaspora, Metschnikowia, Mrakia, Pichia, Rhodotorula, Saccharomyces, Sporobolomyces, Torulaspora, and Trichosporon.Peat samples from the high bog were dominated by eurytopic anamorphic basidiomycetous species, such as Rhodotorula mucilaginosaand Sporobolomyces roseus, and by the ascomycetous yeasts Candidaspp. and Debaryomyces hansenii.These samples also contained two rare ascomycetous species (Candida paludigenaand Schizoblastosporion starkeyi-henricii), which so far have been found only in taiga wetland soils. The wetland Alaskan soil was dominated by one yeast species (Cryptococcus gilvescens), which is a typical inhabitant of tundra soils. Therefore, geographic factors may serve for a more reliable prediction of yeast diversity in soils than the physicochemical or ecotopic parameters of these soils.     

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.

     

Transformation of D-xylose by sporobolomyces lactosus

The new yeast species, Sporobolomyces lactosus, transformed D-xylose into a mixture of disaccharides. Hydrolysis of this mixture yielded D-glucose only. The main component of disaccharide mixture was α,α-trehalose.     

Distribution and immunological characterization of microbial aldehyde reductases

The distribution of microbial aldo-keto reductases was examined and their immunochemical characterization was performed. p-Nitrobenzaldehyde, pyridine-3-aldehyde and ethyl 4-chloro-3-oxobutanoate reductase activities were found to be widely distributed in a variety of microorganisms. In immunodiffusion studies, most yeasts belonging to the genera Sporobolomyces, Sporidiobolus and Rhodotorula formed precipitin bands with anti-Sporobolomyces salmonicolor aldehyde reductase serum. Furthermore, the results of immunotitration experiments suggested that Sporobolomyces salmonicolor AKU 4429 contains other enzyme(s) which can reduce p-nitrobenzaldehyde, pyridine-3-aldehyde and/or ethyl 4-chloro-3-oxobutanoate, and which are inactivated by anti-Sporobolomyces salmonicolor aldehyde reductase serum.     

A comparative study on the intrinsic rates of increase ofCyrtobagous singularis andC. salviniae on the water weedSalvinia molesta

The intrinsic rates of increase (r_m) ofCyrtobagous salviniae Calder & Sands from Brazil andC. singularis Hustache from Trinidad W.I., were determined in the laboratory at 23°C, 27°C and 31°C on nitrogen-rich plants of the aquatic weed,Salvinia molesta Mitchell.Variation in oviposition and immature survivorship accounted for most of the differences between species in r_m values (exponential growth of a stable-age population in a non-limiting environment). Values for r_m were higher forC. salviniae (0.210, 0.366, 0.404) than forC. singularis (0.148, 0.140, 0.064) at the three temperatures respectively. At all temperatures,C. salviniae laid seven times more eggs thanC. singularis while at 31°C oviposition was reduced for both species by 45%, and was accompanied by a reduction in egg hatch. Oviposition byC. salviniae was almost continuous (92% of weeks with some eggs laid) whereas oviposition byC. singularis was intermittent (50% of weeks) with intervals averaging 3 weeks without oviposition. Nitrogen concentration inS. molesta affected reproduction byC. singularis more thanC. salviniae, an increase of 0.1% (dry wt) increasing weekly oviposition by 7.0% and 3.6% respectively.The differences in r_m for the two weevil species are discussed in relationship to their potential as biological control agents.

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Taux intrinsèques d'accroissement deCyrtobagous singularies Hustache andC. salviniae Calder & Sands, utilsés dans la lutte biologique contreSalvinia molesta Mitchell

Résumé Les taux intrinsèques d'accroissement (r_m) deC. salviniae du Bresil et deC. singularis de Trinidad, ont été établis au laboratoire à 23°C; 27°C; 31°C, sur des plants deS. molesta riches en azote.Les différences entre les r_m des deux espèces provenaient pour l'essentiel de la ponte et de la mortalité préimaginale. Aux 3 températures, les valeurs de r_m deC. salviniae (0.210; 0.366; 0.404) étaient supérieures à celles deC. singularis (0.148; 0.140; 0.064). A toutes les températuresC. salviniae a pondu 7 fois plus d'oeufs queC. salviniae; à 31°C, la ponte a été réduite de 45% pour les 2 espèces et été accompagnée d'une diminution des taux d'éclosion. La ponte deC. salvinae était presque continue (92% des semaines avec des oeufs), tandis que celle deC. singularis était intermittent (50% des semaines avec pontes), les interruptions étant en moyenne de 2 semaines. La teneur deS. molesta en azote a affecté la reproduction deC. singularis plus que celle deC. salviniae; un accroissement de 0.1% en poids sec, augmentant les pontes hebdomadaires respectivement de 7% et de 3.6%.Les différences de valeur de r_m des 2 espèces sont examinées pour évaluer leurs potentialités comme éléments de la lutte biologique.

     

Heterologous Expression of a Bioactive β-Hexosyltransferase,an Enzyme Producer of Prebiotics,from Sporobolomyces singularis

Galacto-oligosaccharides (GOS) are indigestible dietary fibers that are able to reach the lower gastrointestinal tract to be selectively fermented by health-promoting bacteria. In this report, we describe the heterologous expression of an optimized synthetically produced version of the β-hexosyltransferase gene (Bht) from Sporobolomyces singularis. The Bht gene encodes a glycosyl hydrolase (EC 3.2.1.21) that acts as galactosyltransferase, able to catalyze a one-step conversion of lactose to GOS. Expression of the enzyme in Escherichia coli yielded an inactive insoluble protein, while the methylotrophic yeast Pichia pastoris GS115 produced a bioactive β-hexosyltransferase (rBHT). The enzyme exhibited faster kinetics at pHs between 3.5 and 6 and at temperatures between 40 and 50°C. Enzyme stability improved at temperatures lower than 40°C, and glucose was found to be a competitive inhibitor of enzymatic activity. P. pastoris secreted a fraction of the bioactive rBHT into the fermentation broth, while the majority of the enzyme remained associated with the outer membrane. Both the secreted and the membrane-associated forms were able to efficiently convert lactose to GOS. Additionally, resting cells with membrane-bound enzyme converted 90% of the initial lactose into GOS at 68% yield (g/g) (the maximum theoretical is 75%) with no secondary residual (glucose or galactose) products. This is the first report of a bioactive BHT from S. singularis that has been heterologously expressed.     

Redescription of Paralagenophrys singularis (Kellicott) n. comb. (Ciliophora: Peritricha: Lagenophryidae)1

Lagenophrys singularis is removed from Lagenophrys and designated the type species of Paralagenophrys n. g. Compared to members of Lagenophrys, the oral area of P. singularis is radically distorted. Paralagenophrys apparently also lacks second-type division, a special phase of sexual reproduction characteristic of Lagenophrys and associated with its adaptation to symbiotic life on crustaceans. Members of Lagenophrys are obligate ectocommensals of crustaceans. In contrast, P. singularis (Kellicott, 1887) n. comb. occurs most often on the leaves of aquatic vascular plants.     

Two new species of the genus Sporobolomyces and a new Rhodotorula species from leaf surfaces

Two new species of the genus Sporobolomyces and one of the genus Rhodotorula are described. Sporobolomyces elongatus and Rhodotorula armeniaca spp. nov. were isolated from the surfaces of leaves of Callistemon viminalis (Soland ex Gaertn.) G. Don ex Loud. and Sporobolomyces foliicola from the leaves of Banksia collina R. Br. growing at Armidale.     

Four new species of the genusSporobolomyces isolated from leaves in Thailand

Thirteen undescribed strains of ballistoconidium-forming yeasts, isolated from leaves collected in the suburbs and along the southeast seacoast of Bangkok, Thailand, were divided into four different groups in the genusSporobolomyces on the basis of morphological, physiological, biochemical, and chemotaxonomical characteristics, and analyses of the sequences of 18S rDNA and internal transcribed spacer regions. DNA-DNA reassociation experiments with related species revealed that these four groups were four new distinct species.Sporobolomyces nylandii sp. nov.,S. poonsookiae sp. nov.,S. blumeae sp. nov. andS. vermiculatus sp. nov. are proposed for these strains.     

A new species of Caprellinoides (Crustacea: Amphipoda: Phtisicidae) from the Antarctic

A new caprellid species, Caprellinoides singularis, is described and illustrated based on the material collected on the Polarstern Cruise ANT XVII/3 from the Branfield Strait. The most striking characteristic of this species is the presence of bilobed gills on pereonites 3 and 4. The genus Caprellinoides is revised. Caprellinoides antarctica Schellengerg, 1926 and Caprellinoides spinosus Barnard, 1930 are considered junior synonyms of Caprellinoides tristanensis Stebbing, 1888 and Caprellinoides mayeri (Pfeffer, 1888), respectively. The new species, C. singularis, is compared with the remaining species in the genus Caprellinoides: C. tristanensis and C. mayeri, which are illustrated in detail. Received in revised form: 4 June 2001 Electronic Publication     

Production and Characterization of an Exopolysaccharide by Yeast

Antarctic yeast strains were investigated for exopolysaccharide biosynthesis and the Sporobolomyces salmonicolor AL₁ strain was selected. It was studied for exopolysaccharide biosynthesis on different carbon and nitrogen sources. The investigations showed that sucrose and ammonium sulphate were suitable culture medium components for polymer biosynthesis. Exopolysaccharide formation by the yeast strain was accompanied by a decrease in the culture medium pH value from the initial pH 5.3 to pH 1.7–2.0. During the biosynthetic process, the dynamic viscosity of the culture broth increased to the maximum value of 15.37 mPas and the polysaccharide yield reached 5.63 g/l on a culture medium containing 5.00% sucrose and 0.25% ammonium sulphate at a temperature of 22 °C for 120 h. The crude polysaccharide obtained from Sp. salmonicolor AL₁ featured high purity (90.16% of carbon content) and consisted of glucose (54.1%), mannose (42.6%) and fucose (3.3%). Pure mannan containing 98.6% of mannose was isolated from it.     

Alkalitolerant Yeasts from Natural Biotopes

Using a solid nutrient medium containing alkaline buffer (pH 10) and an antibiotic, alkalitolerant yeasts were isolated from samples of soda-rich saline soils (solonchaks) of Armenia (Arazdayan) and the Transbaikal region (the Kungur Steppe). The species diversity of the yeast populations of the tested soda-rich soils was relatively insignificant. They only contained alkalitolerant representatives of asporogenic capsulated yeasts belonging to the species Cryptococcus laurentii, C. albidus, Rhodotorula glutinis, R. mucilaginosa,and Sporobolomyces roseus. C. laurentii representatives clearly dominated the isolates obtained, their number exceeding that of the other species by two to three orders of magnitude. All of the isolates grew on acidic wort agar, suggesting that they did not include obligate alkaliphiles.     

Changes in a hydropsychid guild downstream from a eutrophic impoundment

The production of unicellular algae is laborious and is a major constraint for the culturing of aquatic filter-feeders. Because of their small particle size and their high protein content yeasts are considered as a promising substitute for micro-algae. Furthermore, recent work has shown that baker's yeast can be converted into a digestible diet for Artemia by chemical treatment. The present study documents the use at laboratory scale of this manipulated yeast as an algal substitute for the culture of two anostracan species. The experiments were conducted with the brine shrimp artemia franciscana and the fairy shrimp Streptocephalus proboscideus. A similar experimental set-up was used for both species. The algal diet, consisting of Dunaliella tertiolecta for A. franciscana and Selenastrum capricornutum for S. proboscideus, was substituted at various levels by two types of treated baker's yeast: a fresh form and a dried product which was rich in highly unsaturated fatty acids (HUFA). The chemically-treated yeast offers promising possibilities as an algal substitute for Artemia; i.e. replacing 75% of the algae by the dried yeast resulted in similar survival and even higher growth rates in comparison with the reference algal diet; for the treated fresh yeast similar results could be achieved by up to 95% substitution. For S. proboscideus, a substitution of 75% by either of the yeast products resulted in good survival, though growth did not exceed 80% of the observed growth in the algal control. A diet consisting solely of yeast resulted in poor survival for larvae of both species. Experiments were run to investigate whether this was due to a sub-optimal feeding regime, nutritional deficiencies, or deterioration of the water quality.