Emendation of Dioszegia with redescription of Dioszegia hungarica and two new combinations,Dioszegia aurantiaca and Dioszegia crocea

During phylogenetic analyses of hymenomycetous yeasts based on 18S rDNA sequences, we found that Bullera armeniaca showed an extremely close phylogenetic relationship to Cryptococcus hungaricus. The analyses of internal transcribed spacer (ITS) regions of the two yeasts and the phylogenetically related species, Bullera aurantiaca and Bullera crocea, showed that B. armeniaca and C. hungaricus had identical sequences, indicating that these were conspecific. B. aurantiaca and B. crocea also showed high sequence similarity, 97.1% for ITS1, 100% for ITS2, and 98.7% for overall ITS regions. A DNA-DNA reassociation experiment revealed that B. armeniaca and C. hungaricus were conspecific and B. aurantiaca and B. crocea were two distinct species. These species occurred at a phylogenetically different lineage from that of Bulleromyces albus (anamorph: Bullera alba, type species of Bullera) and Filobasidiella neoformans (anamorph: Cryptococcus neoformans, neotype species of Cryptococcus). Based on these results, we emend the genus Dioszegia to include both ballistoconidium-forming and non-ballistoconidium-forming yeasts and redescribe the species Dioszegia hungarica. B. aurantiaca and B. crocea are also transferred to Dioszegia as Dioszegia aurantiaca comb. nov. and Dioszegia crocea comb. nov.     

Diversity of Cryptococcus and Dioszegia yeasts (Basidiomycota) inhabiting arbuscular mycorrhizal roots or spores

The genera Cryptococcus and Dioszegia contain basidiomycetous yeasts found in a wide range of habitats. Primers to amplify the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA (nrDNA) of arbuscular mycorrhizal fungi (AMF) also allow detecting members of this yeast group. Here we report the results of a sequence analysis using maximum parsimony on a set of 50 ITS sequences of yeasts associated with AMF structures (roots of 26 plant species, AM spores) from six field sites in Central Germany. Among 10 separated taxa, respectively five in the Tremellales and two in the Filobasidiales had unknown sequences. Therefore it was not possible to assign these sequences to any known species. The study indicates that exploring the diversity of Cryptococcus and Dioszegia in soil habitats with molecular methods might enlarge the actually estimated biodiversity of the group.     

Biodiversity of cold-adapted yeasts from glacial meltwater rivers in Patagonia, Argentina

The occurrence of culturable yeasts in glacial meltwater from the Frías, Casta?o Overo and Río Manso glaciers, located on Mount Tronador in the Nahuel Huapi National Park (Northwestern Patagonia, Argentina) is presented. Subsurface water samples were filtered for colony counting and yeast isolation. The total yeast count ranged between 6 and 360 CFU L(-1). Physiologic and molecular methods were employed to identify 86 yeast isolates. In agreement with yeast diversity data from studies for Antarctic and Alpine glaciers, the genera Cryptococcus, Leucosporidiella, Dioszegia, Rhodotorula, Rhodosporidium, Mrakia, Sporobolomyces, Udeniomyces and Candida were found. Cryptococcus and Leucosporidiella accounted for 50% and 20% of the total number of strains, respectively. Among 21 identified yeast species, Cryptococcus sp. 1 and Leucosporidiella fragaria were the most frequent. The typically psychrophilic Mrakia yeast strain and three new yeast species, yet to be described, were also isolated. All yeast strains were able to grow at 5, 10, and 15 degrees C. Among yeast strains expressing extracellular enzymatic activity, higher proteolytic and lipolytic activities were obtained at 4 degrees C than at 20 degrees C.     

Two new ballistoconidium-forming yeast species, Bullera melastomae and Bullera formosana, found in Taiwan

Two yeast strains, the cells of which contained xylose and Q-10 as the major ubiquinone, were isolated from a plant leaf collected in Taiwan. These yeasts were found to represent two new species of the genus Bullera in the Hymenomycetes. Identification was based on the sequence analysis of the 18S rDNA, the internal transcribed spacer (ITS) regions and the D1/D2 domain of 26S rDNA. The yeasts are named Bullera melastomae sp. nov. and Bullera formosana sp. nov. In the phylogenetic trees based on 18S rDNA and D1/D2 domain of 26S rDNA sequences, these two species constitute a cluster connected with Dioszegia cluster in the Cryptococcus luteolus lineage.     

Polysaccharides and phenolic compounds as substrate for yeasts isolated from rotten wood and description of Cryptococcus fagi sp.nov.

Pieces of rotten wood collected in the forest were screened for the presence of yeasts. In spring time 3 tree species were sampled, followed by 9 species in summer. Yeast strains were identified by traditional methods. Identifications were confirmed by sequencing of ribosomal DNA in case of doubt. In total 14 yeast species of ascomycetous affiliation and 6 anamorphic basidiomycetous yeasts were isolated and identified. Most species were represented by only one strain, but Candida bertae by two and Trichosporon porosum by six strains, all from different wood samples. Three strains represented novel species, one of which is described as Cryptococcus fagi Middelhoven et Scorzetti. The type strain is CBS 9964 (JCM 13614). All strains were tested for growth on several polysaccharides as sole carbon source. Only some of these polymers supported growth of ascomycetous yeasts. Basidiomycetous yeasts assimilated soluble starch, pullulan, dextran, xylan, polygalacturonate, galactomannan and tannic acid or at least some of these. Cryptococcus podzolicus and T. porosum were the most active in this respect. None of the isolated strains grew on carboxymethyl cellulose, colloidal chitin, arabinogalactan and gum xanthan. Phenolic compounds were assimilated by several strains, belonging to the Trichosporonales and the Microbotryum and Stephanoascus/Blastobotrys clades, but not by members of the Tremellales (Cryptococcus musci excepted) and the Debaryomyces/Lodderomyces clade. Most of the ascomycetes assimilated n-hexadecane.     

Molecular phylogeny of basidiomycetous yeasts in the Cryptococcus luteolus lineage (Tremellales) based on nuclear rRNA and mitochondrial cytochrome b gene sequence analyses: proposal of Derxomyces gen. nov. and Hannaella gen. nov., and description of eight novel Derxomyces species

Phylogenetic relationships among the hymenomycetous yeasts in the Cryptococcus luteolus lineage of the Tremellales were examined based on sequence analyses of the 18S rRNA gene, 26S rRNA gene D1/D2 domain, internal transcribed spacer (ITS) region including 5.8S rRNA gene and mitochondrial cytochrome b gene. In addition to the Dioszegia clade, two clades represented by Bullera mrakii and Bullera sinensis, respectively, were revealed to be well-separated monophyletic groups in the lineage. These clades also exhibited distinguishable colony characters. Two new genera, Derxomyces gen. nov. (type species: Derxomyces mrakii comb. nov.) and Hannaella gen. nov. (type species: Hannaella sinensis comb. nov.), are proposed to accommodate the species in the B. mrakii and B. sinensis clades, respectively. Mainly based on D1/D2 and ITS sequence comparison, eight novel Derxomyces species were recognized from ballistoconidium-forming strains isolated from plant leaves. The new species and their type strains are as follows: Derxomyces boekhoutii (AS 2.3758(T)=CBS 10824(T)), Derxomyces hainanensis (AS 2.3467(T)=CBS 10820(T)), Derxomyces linzhiensis (AS 2.2668(T)=CBS 10827(T)), Derxomyces pseudocylindrica (AS 2.3778(T)=CBS 10826(T)), Derxomyces qinlingensis (AS 2.2446(T)=CBS 10818(T)), Derxomyces simaoensis (AS 2.3571(T)=CBS 10822(T)), Derxomyces wuzhishanensis (AS 2.3760(T)=CBS 10825(T)) and Derxomyces yunnanensis (AS 2.3562(T)=CBS 10821(T)).     

Taxonomic and phenotypic characterization of yeasts isolated from worldwide cold rock-associated habitats

Yeast strains isolated from rock samples collected from worldwide cold regions were identified by sequence analysis of the D1/D2 domains of the 26S rDNA gene and the ITS region followed by molecular phylogeny. Over 77 % of yeasts isolates were Basidiomycota. Cryptococcus (orders Filobasidiales and Tremellales) and Rhodotorula (order Cystobasidiales) were the most frequent genera. About 40 % of yeast isolates belonged to undescribed species.     

Molecular identification of yeasts from soils of the alluvial forest national park along the river Danube downstream of Vienna, Austria ("Nationalpark Donauauen")

We analysed the diversity of yeasts from different soils in a river-floodplain landscape at the river Danube downstream of Vienna, Austria ("Nationalpark Donauauen"). 136 strains were isolated, identification of species was done with molecular methods. Partial sequencing of the 26S rRNA gene resulted in 36 different sequences, they could be assigned to 16 genera, apart from two sequence types (from three isolates), which were not clearly assigned to any genus. 18 species were identified and confirmed by means of PCR fingerprinting. The most frequently isolated genus was Cryptococcus (61 isolates and 12 sequence types). Basidiomycetes dominated with about 60% above the members of the Ascomycetes. About half the yeasts was isolated from the litter, the quantity decreased with soil depth.     

Psychrophilic yeasts in glacial environments of Alpine glaciers

The presence of psychrophilic yeasts in supra- and subglacial sediments, ice and meltwater collected from two glaciers of the Italian Alps (Forni and Sforzellina-Ortles-Cevedale group) was investigated. After incubation at 4 degrees C, subglacial sediments contained from 1.3 x 10(3) to 9.6 x 10(3) CFU of yeasts g(-1). The number of yeast cells in supraglacial sediments was c. 10-100-fold lower. A significant proportion of isolated yeasts exhibited one or more extracellular enzymatic activities (starch-degrading, lipolytic, esterolytic, proteolytic and pectinolytic activity) at 4 degrees C. Selected isolates were able to grow at 2 degrees C under laboratory-simulated in situ conditions. In all, 106 isolated yeasts were identified by MSP-PCR fingerprinting and 26S rRNA gene sequencing of the D1/D2 region as belonging to 10 species: Aureobasidium pullulans, Cryptococcus gilvescens (over 50% of the total), Cryptococcus terricolus, Mrakia gelida, Naganishia globosa, Rhodotorula glacialis, Rhodotorula psychrophenolica, Rhodotorula bacarum, Rhodotorula creatinivora and Rhodotorula laryngis. Four strains, all belonging to a new yeast species, yet to be described, were also isolated.     

云南程海湖酵母菌多样性及应用

【目的】针对云南丽江永胜县境内程海湖环境的特殊性,研究高原湖泊环境中酵母菌的多样性,初步探索程海湖环境中酵母菌的利用价值。【方法】对程海湖的湖水和其周边土壤样品中的酵母菌进行分离;应用26S rDNA的D1/D2区域序列分析,并结合形态及生理生化指标对分离获得的酵母菌进行鉴定;采用筛选培养基对已鉴定酵母菌进行产酶定性实验,分析高原湖泊中酵母菌的多样性及可应用性。【结果】分离得到酵母菌64株,对其中63株进行鉴定,归属于9个属22个种(包括4个疑似新种或新变种);地霉属Geotrichum和隐球酵母属Cryptococcus是2种环境中的共有属;在产酶活性筛选中发现有9株产胞外酶活性的菌株,其中YM24373既产蛋白酶又可产淀粉酶。【结论】研究结果显示程海湖中酵母菌组成具有较为丰富的多样性,其应用价值值得进一步研究。     

Identification and Molecular Analysis of Pathogenic Yeasts in Droppings of Domestic Pigeons in Beijing, China

Feral pigeons are known as reservoirs of pathogenic yeasts that cause opportunistic infections in human. In the outskirts of Beijing, China, pigeons are more frequently raised at homes than are encountered in public areas. Many studies have focused on the presence of pathogenic yeasts in the excreta (fresh or withered) of a variety kinds of birds, pigeon crop and cloacae. One hundred and forty-three samples of fresh droppings were collected from three suburban pigeon-raising homes in an area of northern Beijing, China. The internal transcribed sequences (ITS) of all strains (except for 8 strains of Rhodotorula sp. ) were sequenced and compared with those of the databases of the National Center for Biotechnology Information website ( http://www.ncbi.nlm.nih.gov ) using the Basic Local Alignment Search Tool (BLAST). Yeasts representing 8 genera, Cryptococcus, Filobasidium, Rhodotorula, Candida, Debaryomyces, Saccaromyces, Trichosporon and Sporidiobolus, were identified from 120 isolates. Cryptococcus was the most prolific genera represented by eight species. The populations of yeast species isolated from fresh pigeon droppings were different among homes. Although it is well established that Cryptococcus neoformans exists mainly in old pigeon guano, several C. neoformans strains were still isolated from fresh pigeon excreta, providing a clue that live cryptococcal cells could move through the gastrointestinal tract of the pigeons. Eight genera identified from fresh droppings of domestic pigeons further confirm that pigeons serve as reservoirs, carriers and even spreaders of Cryptococcus species and other medically significant yeasts. The proportion of pathogenic yeasts in all isolates is more than 90 %.     

Utilization of tartaric acid and related compounds by yeasts: taxonomic implications.

A survey of yeasts capable of growing on L(+)-tartaric acid as the sole source of carbon and energy showed that this organic acid is assimilated by a significant number of species of basidiomycetous affinity and is seldom utilized by ascomycetous yeasts. This conclusion was further supported by the fact that among approximately 100 isolates from various natural substrates, using selective media with L(+)-tartaric acid, only one strain of ascomycetous affinity was obtained. In a more comprehensive survey 442 yeast strains belonging to 138 species, mostly of basidiomycetous affinity, were also screened for the assimilation of different aldaric acids: D(-)-tartaric acid, meso-tartaric acid, L(-)-malic acid, D(+)-glucaric acid (saccharic acid), and galactaric acid (mucic acid). L(+)-Tartrate was the most frequently utilized tartaric acid isomer (55% of the total number of strains of basidiomycetous affinity belonging to either the Tremellales/Filobasidiales or the Ustilaginales) when compared with the D(-) and meso forms, which were assimilated by 12 and 18% of the total number of strains, respectively (mainly of tremellaceous species). Saccharic acid was utilized by about 75% of the total number of species of Tremellales affinity and by less than 20% of the ustilaginaceous species. Assimilation of mucic acid occurred in more than 50% of the tremellaceous species and only in 5% of the species related to the Ustilaginales. These tests, not used in standard yeast identification sets, appear to contribute to distinguishing taxa at or above the species level.     

Identity and biodegradative abilities of yeasts isolated from plants growing in an arid climate

Plants harvested in the Canary Islands Lanzarote and Fuerteventura were analyzed for the yeasts inhabiting their surface. Half of the isolates (22 out of 44) were identified as Debaryomyces hansenii. Black ascomycetes, viz. Hortaea werneckii and two Hormonema species were represented by 7 strains. Basidiomycetous yeasts, viz. Cryptococcus sp. (8 strains), Rhodotorula sp. (5 strains), Cerinosterus cyanescens (1 strain) and Pseudozyma sp. (1 strain) constituted a minority of 33%. Thirty strains were screened for their ability to assimilate various plant constituents including lipids of the cuticle and the cell membrane, hemicelluloses, nitrogenous compounds (protein, nucleic acids, amino acids) and benzene compounds. All strains were able to assimilate or to hydrolyze lipids, lecithin included. Many strains of D. hansenii, H. dematioides, H. werneckii, C. cyanescens, Cr. laurentii, Pseudozyma sp. and Rh. glutinis were proteolytic. Hemicelluloses like xylan and pectin were assimilated by black ascomycetous yeasts, Cryptococcus sp., Pseudozyma sp. and Rh. glutinis. Ferulic and hydroxycinnamic acids, gallic and tannic acids were assimilated by some strains of H. dematioides, C. cyanescens, Pseudozyma sp. and Rhodotorula sp.     

Isolation of proteolytic psychrotrophic yeasts from fresh raw seafoods

A total of 103 cultures of yeasts were isolated from seven kinds of fresh raw seafoods. The isolates comprised six genera, Candida, Cryptococcus, Debaryomyces, Rhodotorula, Sterigmatomyces and Trichosporon , and included 21 different species. All the isolates were psychrotrophic yeasts. Proteolytic activities of 50 psychrotrophic strains were studied by use of skim milk within the temperature range of 0–42°C. All the strains showed various degrees of proteolysis. In particular, Candida lipolytica. Trichosporon pullulans and Candida scottii were active species at low temperatures. Sensory spoilage due to the proteolytic yeasts were observed in mackerel homogenates stored at 10°C. C. lipolytica -inoculated homogenates caused spoilage with ammoniacal odours after 1 week of storage. Values of total volatile basic nitrogen at 10°C were highest with C. lipolytica among 35 strains tested, followed by Tr. pullans. Trichosporon cutaneum, C. scottii, Rhodotorula glutinis and Cryptococcus luteolus. Proteolytic psychrotrophic yeasts were widely distributed in raw seafoods.     

Extracellular enzymatic activities of basidiomycetous yeasts isolated from glacial and subglacial waters of northwest Patagonia (Argentina)

As part of a project aimed at the selection of cold-adapted yeasts expressing biotechnologically interesting features, the extracellular enzymatic activity (EEA) of basidiomycetous yeasts isolated from glacial and subglacial waters of northwest Patagonia (Argentina) was investigated. Ninety-one basidiomycetous yeasts (belonging to the genera Cryptococcus, Leucosporidiella, Dioszegia, Mrakia, Rhodotorula, Rhodosporidium, Sporobolomyces, Sporidiobolus, Cystofilobasidium, and Udeniomyces) were screened for extracellular amylolytic, proteolytic, lipolytic, esterasic, pectinolytic, chitinolytic, and cellulolytic activities. Over 15% of the strains exhibited three or more different EEAs at 4 degrees C and more than 63% had at least two EEAs at the same temperature. No chitinolytic or cellulolytic activities were detected at 4 and 20 degrees C. Cell-free supernatants exhibited significantly higher (P < 0.01) protease and lipase activities at < or = 10 degrees C, or even at 4 degrees C. In light of these findings, cold environments of Patagonia (Argentina) may be considered a potential source of cold-adapted yeasts producing industrially relevant cold-active enzymes.     

Medium Containing Trypan Blue and Antibiotics for the Detection of Cryptococcus neoformans in Clinical Samples

A medium containing trypan blue, gentamicin, and chloramphenicol is introduced for the detection of Cryptococcus neoformans and Cryptococcus species from clinical samples. Ten recently isolated strains of Cryptococcus species as well as several clinical isolates of C. neoformans incorporated trypan blue and produced dark blue colonies on this mycological medium, whereas other common yeasts were light blue. The laboratory diagnosis of two cases of cryptococcosis was accomplished by the isolation of C. neoformans on the antibiotic-dye-containing medium. Compared to conventional media supporting large numbers of Pseudomonas aeruginosa and other gram-negative bacilli, the new medium was selective for yeasts. In one instance, the colonization of the respiratory tract by C. neoformans which led to fungemia was traced by the use of the antibiotic-dye medium. The antibiotic mixture, utilized herein, was more effective in suppressing bacteria contained in samples from patients than a medium containing cycloheximide and chloramphenicol.     

Cold-adapted yeasts as producers of cold-active polygalacturonases

Eight cold-adapted, polygalacturonase-producing yeasts belonging to four species were isolated from frozen environmental samples in Iceland. They were identified as Cystofilobasidium lari-marini, Cystofilobasidium capitatum, Cryptococcus macerans and Cryptococcus aquaticus species by sequence analysis of rDNA regions. Growth behavior of the isolates was investigated. All strains could grow at 2 degrees C. Addition of glucose to pectin-containing culture medium had a repressive effect on enzyme production except for C. aquaticus, which showed increased polygalacturonase activity. Optimal temperature for enzyme production for the Cystofilobasidium strains was 14 degrees C, while that for the Cryptococcus strains was lower. Among the isolates, C. lari-marini S3B produced highest levels of enzyme activity at pH 3.2. Preliminary characterization of the polygalacturonases in the culture supernatant showed the enzyme from Cystofilobasidium strains to be optimally active at 40 degrees C and pH 5, and that from the Cryptococcus strains at 50 degrees C and pH 4. The polygalacturonase from C. macerans started to lose activity after 1 h of incubation at 40 degrees C, while that from the other strains had already lost activity at 30 degrees C. All the strains except C. aquaticus produced isoenzymes of polyglacturonase. In addition to polygalacturonase, the Cystofilobasidium strains produced pectin lyase, C. aquaticus pectin esterase, and C. macerans pectin lyase, pectate lyase and pectin esterase.     

Dioszegia zsoltii sp. nov., a new ballistoconidium-forming yeast species with two varieties

As a result of conventional characterization of yeasts isolated from various plant leaves collected in Yunnan, China, six ballistoconidium-forming strains with orange-colored colonies were grouped together. Molecular phylogenetic analysis based on 18S rDNA sequencing showed that two representative strains of this group of yeasts, CH 2.068 and CH 2.497, were closely related to the species in the genus Dioszegia and had signature sequences typical of this genus. However, the six strains from Yunnan differed from the described Dioszegia species remarkably (14.5-17.7% nucleotide divergences) in the ITS (internal transcribed spacer) region sequences, which indicated that they represent a distinct species. Furthermore, among the six strains studied, the ITS region sequence comparison allowed the recognition of two subgroups represented by CH 2.068 and CH 2.497, which differ from each other in three bases in the ITS 2 region. DNA-DNA relatedness revealed that the two subgroups represent two varieties of a new species in the genus Dioszegia, for which Dioszegia zsoltii sp. nov. var. zsoltii and Dioszegia zsoltii var. yunnanensis var. nov. are proposed.