Genus Lipomyces Research Articles

North-to-South diversity of lipomycetaceous yeasts in soils evaluated with a cultivation-based approach from 11 locations in Japan.

To understand the species distribution, diversity, and density of lipomycetaceous yeasts in soil based on their north-to-south location in Japan, 1146 strains were isolated from soil samples at 11 locations from Hokkaido to Okinawa Prefecture and taxonomically characterized. Lipomycetaceous yeast strains were isolated efficiently from soil by selecting watery mucoid-like colonies on agar plates with nitrogen-depleted medium. Twenty-four (80%) of the 30 known species of the genus Lipomyces were isolated from the soil samples collected in Japan, including species recently proposed. Among the species isolated, L. starkeyi was the most predominant in Japan, except on Iriomote Island, Okinawa, and accounted for 60-98% of the isolated strains. Lipomyces yarrowii was the dominant species on Iriomote Island (64%). The second most dominant species were L. chichibuensis in Saitama Prefecture and L. doorenjongii from Yamaguchi to Okinawa Prefecture. The species diversity of lipomycetaceous yeasts was in Japan and the significant correlation with the latitude of the sampling sites was revealed.

Complex intron generation in the yeast genus Lipomyces

In primary transcripts of eukaryotic nuclear genes, coding sequences are often interrupted by U2-type introns. Such intervening sequences can constitute complex introns excised by consecutive splicing reactions. The origin of spliceosomal introns is a vexing problem. Sequence variation existent across fungal taxa provides means to study their structure and evolution. In one class of complex introns called [D] stwintrons, an (internal) U2 intron is nested within the 5'-donor element of another (external) U2 intron. In the gene for a reticulon-like protein in species of the ascomycete yeast genus Lipomyces, the most 5' terminal intron position is occupied by one of three complex intervening sequences consistent of differently nested U2 intron units, as demonstrated in L. lipofer, L. suomiensis, and L. starkeyi. In L. starkeyi, the donor elements of the constituent introns are abutting and the complex intervening sequence can be excised alternatively either with one standard splicing reaction or, as a [D] stwintron, by two consecutive reactions. Our work suggests how [D] stwintrons could emerge by the appearance of new functional splice sites within an extant intron. The stepwise stwintronisation mechanism may involve duplication of the functional intron donor element of the ancestor intron.

Efficiency of synthesis of extracellular polysaccharides strains of Lipomyces yeast

The formation of extracellular polysaccharides is a fairly well-studied property of bacteria that is used for the industrial production of such extracellular bacterial as xanthan, dextran, gellan, hyaluronan, etc.. Polysaccharides synthesized by fungi are also widely used, such as schizophillan and scleroglucan. However, polysaccharides synthesized by yeast and yeast-like fungi have not yet found wide industrial application, with the exception of pullulan produced by Aureobasidium pullulans yeast, although there are a number of promising developments in the use of yeast polysaccharides in medicine. Yeast synthesizes polymers that contain mannans, glucans, phosphomannans, galactomannans, and glucuronoxylmannans. Polysaccharides produced by different species, and sometimes even by different strains of the same species, may differ in chemical composition and structure. Such a variety of composition and properties opens up great prospects for their use in various fields: medicine, chemical, food and cosmetic industries, as well as feed additives. In this regard, the search for new producers of polysaccharides is very relevant. Yeast of the genus Lipomyces is found in the soils of the southern and northern hemispheres of the Earth, except in the high-mountainous regions and tundra soils, where soil formation processes are in early stages of development, but the soils are rich in steppe and forest zones. As a result of the research, it turns out that from the point of view of biomass growth on the presented nutrient medium at the temperatures studied, the strains of the Lipomyces lipofer yeast КБП Y-6267 and КБП Y-6265 attract the most attention, especially at low temperatures. With an increase in temperature, the increase in biomass in these yeasts decreases markedly. As producers of extracellular polysaccharide, it is worth noting the КБП Y-6267 and КБП Y-6264 strains at 20 °C and the КБП Y-6268 strains and the КБП Y-6234 at 30 °C, which indicates the possibility of using for these purposes different species of the genus Lipomyces. At 30 °C, Lipomyces lipofer strains of the КБП Y-6268 and Lipomyces kononenkoae КБП Y-6234 had the highest enzyme activities, however, there was no relationship between enzyme activities, biomass gains and polysaccharide yields at low temperatures.

Two novel Lipomycetaceous yeast species, Lipomyces okinawensis sp. nov. and Lipomyces yamanashiensis f.a., sp. nov., isolated from soil in the Okinawa and Yamanashi prefectures, Japan.

Four novel Lipomyces strains were isolated from soil collected in the Okinawa and Yamanashi prefectures, Japan. Based on their morphological and biochemical characteristics, along with sequence typing using the D1/D2 domain of the LSU rRNA, internal transcribed spacer (ITS) region including 5.8S rRNA, and translation elongation factor 1 alpha gene (EF-1α), the four strains were shown to represent two novel species of the genus Lipomyces, described as Lipomyces okinawensis sp. nov. (type strain No.3-a(35)T=NBRC 110620T=CBS 14747T) and Lipomyces yamanashiensis f.a., sp. nov. (type strain No.313T=NBRC 110621T=CBS 14748T).

Lipomyces chichibuensis sp. nov., isolated in Japan, and reidentification of the type strains of Lipomyces kononenkoae and Lipomyces spencermartinsiae.

We isolated two strains of a novel Lipomyces species from soil collected in Chichibu forest, Saitama prefecture, Japan. Based on their morphological and biochemical characteristics, along with multilocus sequence typing using the D1/D2 domain of the large-subunit (LSU) rRNA gene, the internal transcribed spacer (ITS) region and the translation elongation factor 1 alpha gene (EF-1α), the two strains were shown to represent a novel species of the genus Lipomyces, described as Lipomyces chichibuensis sp. nov. (type strain CB08-2(T) = NBRC 109582(T) = CBS 12929(T); Mycobank no. MB808164). In addition, we reidentified the type strains of Lipomyces kononenkoae and Lipomyces spencermartinsiae maintained in culture collections based on phenotypic characters and/or DNA-DNA hybridization to ensure correct future identification of species of the genus Lipomyces. The correct type strains of L. kononenkoae and L. spencermartinsiae are NBRC 107661(T) ( = CBS 2514(T)) and NBRC 10376(T) ( = CBS 5608(T)), respectively.

Kockiozyma gen. nov., for Zygozyma suomiensis: the phylogeny of the Lipomycetaceous yeasts

In phylogenetic trees based on 18S rRNA gene, 26S rRNA gene, mitochondrial small subunit rRNA gene and the EF-1α gene sequences, and the concatenated sequences of the latter four regions derived from the neighbor-joining method, the four species of the genus Zygozyma constituted four clusters, respectively, with low bootstrap values. In phylogenetic trees based on the concatenated sequences of 18S rRNA genes, 26S rRNA genes, mitochondrial small subunit rRNA genes and the EF-1α genes derived from the neighbor-joining method, the maximum parsimony method and the maximum likelihood method, Lipomyces species including Lipomyces starkeyi (the type species of the genus Lipomyces), Lipomyces tetrasporus and so on, Lipomyces lipofer (= Waltomyces lipofer), Lipomyces japonicus (= Smithiozyma japonica), Babjevia anomala (= Lipomyces anomalus) and Dipodascopsis uninucleata constituted their own respective clusters. The four species of the genus Zygozyma, viz., Zygozyma oligophaga (the type species of the genus Zygozyma), Zygozyma suomiensis, Zygozyma arxii (= Kawasakia arxii) and Zygozyma smithiae (= Limtongia smithiae) were separated from one another and phylogenetically independent from other Lipomycetaceous yeast species. From the data obtained, all four species of the genus Zygozyma were distinguished from one another at the generic level. The name of Kockiozyma was newly suggested for Zygozyma suomiensis, and Kockiozyma suomiensis was introduced as a new combination.

UV Irradiation Promotes the Accumulation of Triglyceride inLipomyces lipofer

Yeasts of the genus Lipomyces are known as fat yeasts, and they store large amounts of lipids. Because the major lipid produced by Lipomyces is triglyceride, which can be used as a food and energy resource, the control of lipid production by Lipomyces sp. is an important issue. Here we report the effects of UV irradiation on lipid production in Lipomyces lipofer cells. UV irradiation (315-400 nm) led to a 4-fold increase in the amount of triglyceride per cell. We discovered a novel phenomenon, that UV irradiation promotes triglyceride accumulation in L. lipofer.

Multigene phylogenetic analysis of the Lipomycetaceae and the proposed transfer ofZygozymaspecies toLipomycesandBabjevia anomalatoDipodascopsis

Phylogenetic relationships among species assigned to genera of the family Lipomycetaceae were determined from analysis of the nearly entire large, subunit rRNA gene, the small subunit rRNA gene, mitochondrial small subunit rRNA gene and the translation elongation factor-1alpha gene. Monophyly of the Lipomycetaceae was strongly supported, and currently described species appear genetically unique. The multigene analysis provided no support for maintaining the genera Kawasakia, Smithiozyma, Waltomyces or Zygozyma, and it is proposed that species in these genera be assigned to the genus Lipomyces. The monotypic genus Babjevia is a member of the Dipodascopsis clade and it is proposed to reassign Babjevia anomala to Dipodascopsis. The proposed changes will result in the Lipomycetaceae having two ascosporic genera, Lipomyces and Dipodascopsis, and the anamorphic genus Myxozyma.

Four New Species in Lipomyces

For new species in Lipomyces are described. In terms of nuclear genome comparison the genus Lipomyces comprises three species-clusters. A key to the nine species now assigned to the genus, is given. The delimitation of species by (i) rRNA nucleotide sequence analyses of the 18S and 25S subunits and (II) nDNA homology determinations, do not invariably lead to the recognition of congruent taxa. The family of the Lipomycetaceae, nevertheless provides an illuminative model for phylogenetic studies in terms of more appropriate ribosomal nucleotide sequence analyses of both its teleomorphic and anamorphic members.

An Improved Method for Isolating Yeasts in the Genus Lipomyces and Related Genera from Soil.

An improved method for isolating soil yeasts in the genus Lipomyces and related genera was developed on the basis of their physiological properties. Liberation of yeast cells from soil, capture of the yeast cells by a membrane filter, and colony formation on an acidic (pH 3) nitrogen-free agar plate containing 0.1% cycloheximide resulted in success.

Development of a new chemically defined sporulation medium for the yeasts in the genus Lipomyces.

A chemically defined sporulation medium (AF medium) for the yeasts belonging to the genus Lipomyces was developed. The chemical composition was derived from chemical analyses of soybean extract. Some chemical modification of the AF medium indicated that the nitrogen sources (aspartic and glutamic acids) and zinc ion were essential for sporulation. The significance of medium pH was discussed.

Lipid Composition and DNA Band Patterns in the Yeast Family Lipomycetaceae

Summary The distribution of DNA band patterns (karyotyping) as well as the E3 and E6 fatty acids (FAs) present in the neutral, phospho- and glycolipid fractions in the teleomorphic family of the Lipomycetaceae and related anamorphs in Myxozyma , were determined. Improved DNA band separation was obtained when compared with the band patterns reported for this family by earlier workers. A similar trend in the distribution of the DNA band patterns was, nevertheless, observed in this investigation. In a study which included the analyses of 69 strains representing 19 species, we found that the genus Dipodascopsis , regarded by some as the ancestral representative of this family, produced heavy DNA bands (larger than 1300 kb), while the presumed, more recently evolved representatives assigned to Myxozyma were characterized by much smaller and more numerous bands. In terms of total FA composition of these yeasts, it was found that all representatives of the genus Lipomyces investigated, produced the o)3 polyunsaturated FA, a-linolenic acid (18: 3) while some Zygozyma and Myxozyma species were unable to produce this FA. Babjevia anomala was characterized by only two DNA bands larger than 1300 kb and the presence of 18:3. Seventy four strains, representing 20 teleomorphic species of the Lipomycetaceae and related anamorphs were further analysed for their lipid content when cultivated in a medium containing a high C: N ratio. Under these conditions all the strains were capable of producing the to3 series of 18 : 3 FAs in their polar fractions. Contrary to the belief that the Lipomycetaceae and related anamorphs may all be oleaginous, it was found in this study that only members of the genera Babjevia and Lipomyces (excluding L. japonicus ) actually produce large quantities of lipid. Oleaginicity and the palmitoleic acid (16:1) content in the neutral lipids, proved to be useful in distinguishing between the genera Babjevia, Dipodascopsis and Lipomyces (with the exclusion of L. japorricus ) and Zygozyma . FA and Co Q composition provides additional biochemical evidence for the postulated phylogenetic connexions between Myxozyma and the teleomorphic genera Lipomyces and Zygozyma . It was shown that in terms of oleaginiciry, palmitoleic acid content and DNA band patterns, Babjevia anomala and Lipomyces japonicus occupy isolated positions within the family.

Study of lipids in Lipomyces and Waltomyces

The lipid composition, particularly the fatty acid composition (6–25 carbon atoms), of one strain of each species of Lipomyces and Waltomyces was determined; the influence of the culture temperature on the lipid composition was also studied. The neutral lipid fraction, essentially composed of intracellular triacylglycerols, and the polar fraction, composed of membrane phospholipids, were analyzed separately. For all strains and in the two fractions, the major fatty acids were oleic, linoleic, palmitic, palmitoleic, stearic, and α-linolenic acids, which formed 85% of the total fatty acids. Small amounts of γ-linolenic, dihomo-γ-linolenic, and arachidonic acids were present, which indicated the presence of Δ12, Δ15, Δ6, and Δ5 desaturases. Waltomyces lipofer and Lipomyces tetrasporus were the two species richest in lipids and fatty acids. In the genus Lipomyces and in Waltomyces, maintenance of membrane fluidity at low temperature required an increase in unsaturated fatty acids and the accumulation of short-chain fatty acids, especially in the polar lipid fraction; in the case of Lipomyces anomalus, the synthesis of branched fatty acids may be a third way to maintain membrane fluidity.Key words: Lipomyces, Waltomyces, lipid composition, fatty acids.

Evidence for, and taxonomic value of, an arachidonic acid cascade in the lipomycetaceae

By using specific inhibitors of the lipoxygenase and cyclo-oxygenase pathways, arachidonic acid metabolites with similar sensitivities towards these inhibitors as in humans, were detected in Dipodascopsis uninucleata. The taxonomic value of aspirin sensitive arachidonic acid metabolites in the Lipomycetaceae was next assessed. No metabolites of which the production is inhibited by aspirin were detected in strains representing the following species: Lipomyces starkeyi, Lipomyces kononenkoae, Lipomyces tetrasporus, Myxozyma melibiosi, Myxozyma mucilagina, Myxozyma kluyveri, Waltomyces lipofer, Zygozyma oligophaga and Zygozyma arxii. The detection of such aspirin sensitive arachidonic acid metabolites in representative strains of Lipomyces anomalus and the genus Dipodascopsis, emphasises the isolated position of these taxa in the genus Lipomyces and the family Lipomycetaceae, respectively. Finally using long chain fatty acid analyses, electrophoretic karyotyping and other phenotypic characters, a phylogenetic scheme is proposed for some genera in the Lipomycetaceae.

Myxozyma geophila and Myxozyma lipomycoides spp. nov., two new anamorphic, lipomycetaceous yeasts from Southern Africa

Summary Two undescribed species of the genus Myxozyma have been recovered from surface soils and arboricolous lichen, from South African habitats. The two new species, Myxozyma geophila and Myxozyma lipomycoides , are described and their possible relationship with the genera Lipomyces and Zygozyma is considered. A key for the genus Myxozyma is given.

Ascospore Morphology and Ultrastructure of Species Assigned to the Genus Lipomyces Lodder et Kreger-van Rij

Ascospores of Lipomyces species were examined by transmission electron microscopy. The following four types of ascospore morphology were found in replicas: (i) ascospores with longitudinal ridges; (ii) ascospores with irregular folds; (iii) ascospores with slightly undulating surfaces; and (iv) ascospores with smooth surfaces. In contrast, on the basis of ultrastructure of thin sections, only three types of ascospores were identified.

Extracellular polysaccharides and classification of the genus Lipomyces.

SUMMARY: Strains classified as Lipomyces lipoferus and L. starkeyi produce specific extracellular acidic heteropolysaccharides. The polymer from L. lipoferus contains mannose and glucuronic acid; the polymer from L. starkeyi contains, in addition, galactose and a trisaccharide. This trisaccharide is composed of mannose and glucuronic acid in the molar ratio 1:2. The difference in polysaccharide composition may be the most significant physiological basis yet discovered for separation of species in the genus Lipomyces.

Observations on the yeast Lipomyces.

IN 1946, Starkey1 isolated and described a soil yeast characterized by a peculiar method of spore formation after a relatively long period of growth on solid medium. Large, round vegetative cells containing fat globules gave rise to irregularly shaped protuberances in which were afterwards formed 4–16 or more lightly pigmented spores. Lodder and Kregervan Rij2 considered these spores to be ascospores and erected the genus Lipomyces to include this yeast (L. starkeyi) as well as another soil yeast (L. lipofer) which had originally been described as a Torula. The two species were distinguished primarily on the basis of lactose assimilation, L. starkeyi lacking this ability. Neither species is capable of fermentation, and hitherto germination of the spores has not been observed.