Diversity of Soil Yeasts Isolated from South Victoria Land,Antarctica

Unicellular fungi, commonly referred to as yeasts, were found to be components of the culturable soil fungal population in Taylor Valley, Mt. Discovery, Wright Valley, and two mountain peaks of South Victoria Land, Antarctica. Samples were taken from sites spanning a diversity of soil habitats that were not directly associated with vertebrate activity. A large proportion of yeasts isolated in this study were basidiomycetous species (89%), of which 43% may represent undescribed species, demonstrating that culturable yeasts remain incompletely described in these polar desert soils. Cryptococcus species represented the most often isolated genus (33%) followed by Leucosporidium (22%). Principle component analysis and multiple linear regression using stepwise selection was used to model the relation between abiotic variables (principle component 1 and principle component 2 scores) and yeast biodiversity (the number of species present at a given site). These analyses identified soil pH and electrical conductivity as significant predictors of yeast biodiversity. Species-specific PCR primers were designed to rapidly discriminate among the Dioszegia and Leucosporidium species collected in this study.     

Characteristics of Yeasts Isolated from Pacific Crab Meat

A total of 202 cultures of yeasts were isolated and characterized from king crab and Dungeness crab meat. A yeastlike organism, resembling Aureobasidium pullulans, and 15 different species distributed among the genera Rhodotorula, Cryptococcus, Torulopsis, Candida, and Trichosporon were represented. Nine of the species grew at 5 C or lower. Although two of the species grew at 37 C, none of the isolates had the characteristics of pathogenic species. Members of the Cryptococcus and Candida failed to grow at 37 C. Furthermore, species of the former genus were not pathogenic to mice. The pigmentation of the Rhodotorula cultures decreased in intensity as the incubation temperature was decreased. Biochemical activities of the different species were studied by use of triglycerides, lecithin, and proteins (casein, gelatin, and crab-meat protein) as substrates. Eight of the species could attack triglycerides; eight, lecithin; five, gelatin; one, casein; and one, crab protein. An organism, tentatively identified as Trichosporon sp., was very active in attacking each of the substrates tested and grew well at 0.5 C.     

云南杜鹃花上的酵母菌物种多样性

利用酵母菌常规分类学方法 ,对采自云南省东部、西部及中部地区杜鹃花上的 119株酵母菌进行了分类研究 ,以期弄清其属种分布特点 ,从而为发掘新种、开发酵母菌资源提供依据。这些酵母菌被归入3大类 10个属 ,显示了云南杜鹃花中酵母菌的种类多样性 ,其中优势属为假丝酵母属 (Candida)。     

Bioremediation of Fish Cannery Wastewater with Yeasts Isolated from a Drainage Canal

Several yeasts were isolated from a drainage canal in a Japanese fish food processing factory. They were characterized by the decomposition of organic polymers such as proteins and reducing sugars, their growth in the wastewater, the decrease in total organic carbon (TOC), and taxonomy. Three strains of yeast dominated the sample: Debaryomyces occidentalis (P1), Trichosporon ovoides (P19), and a strain that could not be identified (S27). Strain P19 had the highest TOC-decreasing activity and was immobilized onto chitosan beads. The immobilized yeasts reduced the TOC from 1.2 × 103 to 3.0 × 102 mg of C/L per day in the fish cannery wastewater.     

Yeasts Isolated from Neotropical Wood-Boring Beetles in SE Peru

Some temperate wood-boring cerambycid beetles harbor intracellular gut yeasts believed to augment host nutrition, but species belonging to the subfamily Lamiinae are thought to lack endosymbionts. Almost 49 percent of Neotropical cerambycid species are lamiines, therefore, comparatively few rain forest species would be expected to host symbiotic gut yeasts. This study reports the isolation of gut yeasts from closely related Neotropical lamiines. We investigated species that feed on trees in the Brazil nut family (Lecythidaceae), because host plant associations are relatively well known. Our objectives were to determine if gut yeasts were present and, if possible, infer their mode of transmission. We collected and dissected 18 beetle specimens from three tree species, including 17 cerambycids and one curculionid. Every insect specimen yielded a gut yeast. DNA sequence libraries were used for a rapid identification of the yeasts and their larval hosts. The cerambycids included five lamiine species and one cerambycine. Six ascomycete yeasts were isolated from their guts; we found no evidence of strict vertical transmission. Larval gut yeasts were genetically similar to yeasts previously isolated from insects associated with wood or fungi, implying potential habitat specificity. The yeasts have not yet been localized, and potential function is not known, but they may contribute to rapid nutrient cycling or serve as the first line of defense against plant toxins.     

Electrophoretic Karyotypes of Candida Yeasts Recurrently Isolated from Single Patients

Candida strains were isolated repeatedly from single patients during recurrent episodes of Candida infection in a hospital, and their electrophoretic karyotypes were analyzed by pulsed-field gel electrophoresis using CHEF system. When only C. albicans (in 6 patients) or C. glabrata (in 1 patient) were recurrently isolated, their karyotypes from each patient were almost identical to one another, suggesting that they carried single type of the yeast. When multiple species were recovered from single patients (6 cases), the karyotypes of the most frequently recovered yeast species were almost identical with respect to each patient. The electrophoretic karyotype analysis has been proved to be useful for epidemiological studies because the method can tell not only the species identification but also the differences among the strains of the same species.     

青海东部土壤中酵母物种多样性研究

从青海的互助、民和、门源等10个州县收集土样分离得到98株酵母菌, 利用26S rDNA D1/D2区域序列分析并结合形态学和生理生化特性对这些菌株进行了分类学研究, 探讨了青海东部土壤中酵母的物种多样性及其分布。共鉴定出10属13种(其中有两个疑似新种), 其中 Galactomyces geotrichum和Rhodotorula mucilaginosa为该地的优势种。     

The Genetic Content of Chromosomal Inversions across a Wide Latitudinal Gradient

There is increasing evidence regarding the role of chromosomal inversions in relevant biological processes such as local adaptation and speciation. A classic example of the adaptive role of chromosomal polymorphisms is given by the clines of inversion frequencies in Drosophila subobscura, repeatable across continents. Nevertheless, not much is known about the molecular variation associated with these polymorphisms. We characterized the genetic content of ca. 600 individuals from nine European populations following a latitudinal gradient by analysing 19 microsatellite loci from two autosomes (J and U) and the sex chromosome (A), taking into account their chromosomal inversions. Our results clearly demonstrate the molecular genetic uniformity within a given chromosomal inversion across a large latitudinal gradient, particularly from Groningen (Netherlands) in the north to Málaga (Spain) in the south, experiencing highly diverse environmental conditions. This low genetic differentiation within the same gene arrangement across the nine European populations is consistent with the local adaptation hypothesis for th evolutionof chromosomal polymorphisms. We also show the effective role of chromosomal inversions in maintaining different genetic pools within these inverted genomic regions even in the presence of high gene flow. Inversions represent thus an important barrier to gene flux and can help maintain specific allelic combinations with positive effects on fitness. Consistent patterns of microsatellite allele-inversion linkage disequilibrium particularly in loci within inversions were also observed. Finally, we identified areas within inversions presenting clinal variation that might be under selection.     

Spatial Community Structure of Mountain Pine Beetle Fungal Symbionts Across a Latitudinal Gradient

Symbiont redundancy in obligate insect–fungal systems is thought to buffer the insect host against symbiont loss and to extend the environmental conditions under which the insect can persist. The mountain pine beetle is associated with at least three well-known and putatively obligate ophiostomatoid fungal symbionts that vary in their environmental tolerances. To better understand the spatial variation in beetle–fungal symbiotic associations, we examined the community composition of ophiostomatoid fungi associated with the mountain pine beetle as a function of latitude and elevation. The region investigated represents the leading edge of a recent outbreak of mountain pine beetle in western Canada. Using regression and principal components analysis, we identified significant spatial patterns in fungal species abundances that indicate symmetrical replacement between two of the three fungi along a latitudinal gradient and little variation in response to elevation. We also identified significant variation in the prevalence of pair-wise species combinations that occur within beetle galleries. Frequencies of pair-wise combinations were significantly different from what was expected given overall species abundances. These results suggest that complex processes of competitive exclusion and coexistence help determine fungal community composition and that the consequences of these processes vary spatially. The presence of three fungal symbionts in different proportions and combinations across a wide range of environmental conditions may help explain the success of mountain pine beetle attacks across a broad geographic range.     

The Ability of Saprotrophic Bacteria Isolated from Natural Habitats to Lyse Yeasts

More than 600 bacterial strains isolated from different horizons of steppe biogeocenoses and zoogenous loci (diplopod intestines and feces) were tested for the ability to lyse yeast cell walls. About half of the strains that were isolated from biotopes with active degradation of plant debris (steppe litters and diplopod intestines and feces) were found to possess yeast-lytic activity. Most of the yeast-lytic strains belonged to the genera Streptomyces, Promicromonospora, Oerskovia, and Agromyces. The yeast-lytic activity of actinobacteria from the genera Agromyces, Mycobacterium, and Micrococcus has not previously been reported.     

Mycobacterium malmoense Isolated from Soil

Mycobacterium malmoense was isolated from a soil sample, and biological, biochemical, antigenic, and genetic characteristics of the isolate were described. This is the first report of isolation of this organism in Japan.     

Phosphatase Activity Among Candida Species and Other Yeasts Isolated from Clinical Material

A group of 277 yeasts isolated from burned children and 14 reference strains were tested for phosphatase activity by using phenolphthalein phosphate substrates. Phosphatase activity was widely distributed among various species and strains representing seven genera. Candida albicans, which was the most common yeast isolated from clinical material, was notably absent in producing the enzyme, whereas Candida tropicalis was the most consistent, strong, and rapidly active phosphatase-producing organism. The characteristic enzyme activity of a selected isolate of C. tropicalis was demonstrated in the presence of concentrations of inorganic phosphate which inhibited enzyme activity of other species. The greater enzyme activity of C. tropicalis was not related to more rapid or greater cell growth or decrease in the pH of culture media. Extracellular constitutive heat-labile acid phosphatase was found in broth filtrates of C. tropicalis, C. krusei, and a strain of Staphylococcus aureus.     

Characterisation of Yeasts Isolated from Deep Igneous Rock Aquifers of the Fennoscandian Shield

The diversity of prokaryotes in the groundwater deep below the surface of the Baltic Sea at the Äspö Hard Rock Laboratory (HRL) in southeast Sweden is well documented. In addition, there is some evidence that eukaryotes, too, are present in the deep groundwater at this site, although their origins are uncertain. To extend the knowledge of eukaryotic life in this environment, five yeast, three yeastlike, and 17 mold strains were isolated from Äspö HRL groundwater between 201 and 444 m below sea level. Phenotypic testing and phylogenetic analysis of 18S rDNA sequences of the five yeast isolates revealed their relationships to Rhodotorula minuta and Cryptococcus spp. Scanning and transmission electron microscopy demonstrated that the strains possessed morphological characteristics typical for yeast, although they were relatively small, with an average length of 3 µm. Enumeration through direct counting and most probable number methods showed low numbers of fungi, between 0.01 and 1 cells mL^–1, at some sites. Five of the strains were characterized physiologically to determine whether they were adapted to life in the deep biosphere. These studies revealed that the strains grew within a pH range of 4–10, between temperatures of 4°C and 25–30°C, and in NaCl concentrations from 0 to 70 g L^–1. These growth parameters suggest a degree of adaptation to the groundwater at Äspö HRL. Despite the fact that these eukaryotic microorganisms may be transient members of the deep biosphere microbial community, many of the observations of this study suggest that they are capable of growing in this extreme environment.     

Molecular Identification and Antifungal Susceptibility of Yeasts and Molds Isolated from Patients with Otomycosis

Mycopathologia - Fungal otitis externa, an infection of the external auditory canal caused by molds and yeasts, accounts for approximately 10–20% of ear canal infections accompanying high...     

Molecular Characterization of a Xylanase-Producing Thermophilic Fungus Isolated from Japanese Soil

We describe the molecular characteristics of Scytalidium thermophilum isolated from Japanese soil. The S. thermophilum isolates produced higher xylanase activity than Humicola lanuginosa isolated from Japanese soil. A G/11 family xylanase-encoding gene was detected in the S. thermophilum genome by using the polymerase chain reaction technique. The S. thermophilum AF101-3 strain, which was one of the isolates in this study, grew well at 37°C and 50°C, and contained the maximum xylanase activity detected among the isolates. Phylogenetic analysis revealed that the S. thermophilum strains isolated from Japanese soil were clustered in a different group from the S. thermophilum strains reported by Lyons et al. [Mycol Res 104:1431, 2000], suggesting that the S. thermophilum strains isolated in this study are genetically new isolates. Therefore, the genetic diversity of S. thermophilum might be higher than that of H. lanuginosa. Moreover, this is the first report about detection of a xylanase-encoding gene in S. thermophilum. RID= ID= <E5>Correspondence to: </E5>T. Morinaga; <E5>email:</E5> tmorina&commat;bio.hiroshima-pu.ac.jp Received: 3 July 2002 / Accepted: 25 September 2002     

A New Mesorhizobium loti HAMBI 1129 Phage Isolated from Polish Soil

Phage A1 isolated from the rhizosphere of Lotus corniculatus was studied. It had a very narrow host range, as it was active only against Mesorhizobium loti HAMBI 1129. Phage A1 was classified as belonging to C Bradley's group bacteriophages. The latent period of A1 was 120–130 min and a burst size 13–17 particles per cell. The nature of the phage receptor was examined. Lipopolysaccharide from the phage-sensitive strain inactivated phage A1 in contrast to LPS from the phage-resistant bacteria. Purified LPS obtained from M. loti HAMBI 1129 had a high receptor activity with PhI₅₀ value of 0.025 μg/ml. Received: 30 July 1999 / Accepted: 15 November 1999     

Cacao Fermentation: V. Yeasts Isolated from Cacao Beans during the Curing Process

Cacao beans must be subjected to fermentation before they are used in making chocolate, and their commercial value is related to a proper procedure. Saccharomyces rosei, Hansenula anomala, Pichia fermentans, Pichia membranaefaciens, and Trichosporon cutaneum were found in fermenting cacao beans. All species isolated during the investigation grew on cacao pulp, but only S. rosei, H. anomala, and P. fermentans exhibited fermenting capacity on the sugars of cacao pulp. Species of the genus Saccharomyces were identified as the agents responsible for the alcoholic phase of the cacao fermentation.     

Diversity of Pseudomonas spp. Isolated from Rice Rhizosphere Populations Grown along a Salinity Gradient

Along the coastline of Tamil Nadu, five sites were chosen to assess the diversity of Pseudomonas populations isolated from rice (Oryza sativa) cultivated along a salinity gradient. One of these sites was under organic farming while the other four were under inorganic farming. A total of 256 Pseudomonas strains isolated from these five sites were analyzed using both phenotypic (substrate utilization patterns and antibiotic resistance assay) and genotypic (PCR-RFLP of 16S rDNA) characteristics. The results derived from this study indicate that soil salinity affects rhizosphere Pseudomonas populations. It was observed that increasing salinity led to decreasing diversity. Fluorescent pseudomonads were the dominant species found in the non-saline site, while in the saline sites they were replaced by salt-tolerant species, in particular Pseudomonas alcaligenes and P. pseudoalcaligenes. An interesting observation was the increase in diversity found in the saline site under organic farming. Organic farming was found to be capable of mitigating the harmful effects of saline stress to a large extent, and restoring the Pseudomonas diversity, thereby making it comparable with the diversity encountered in the non-saline site.