Various Species Of Yeasts Research Articles

The epiphytic microbiota of sour rot-affected grapes differs minimally from that of healthy grapes, indicating causal organisms are already present on healthy berries.

Sour rot is a disease complex produced by an interaction between grape berries and various species of yeast and acetic acid bacteria in the presence of Drosophila fruit flies. While yeast and bacteria are consistently found on healthy grape berries worldwide, we explored whether the composition of these epiphytic communities differed depending on the presence or absence of sour rot symptoms. Using high-throughput sequencing, we characterized the microbiome of sour rot-affected grapes from two geographical areas across two years. In 2015 and 2016, both healthy and sour rot-affected berries were collected from commercial and research vineyards in Geneva, NY and commercial vineyards in Tasmania, AUS. In this experiment, all associated organisms grouped together primarily by location, and not by presence/absence of symptoms or cultivar. The predominant difference between asymptomatic and symptomatic samples, regardless of location, was the abundance of Acetobacter species, which were significantly more plentiful in the symptomatic samples. Yeast genera such as Candida, Hanseniaspora, Pichia and Saccharomyces were abundant in both sets of samples, but varied by region. The consistent presence of yeast species and the increased abundance of acetic acid-generating bacteria is consistent with our understanding of their etiological role in sour rot development. In 2016, diseased grapes also were collected from vineyards in Fredonia, NY, and Modesto, CA. Consistent with our comparison study, all associated organisms again grouped together primarily by location. Yeast genera such as Candida, Hanseniaspora, Pichia and Saccharomyces were abundant in both sets of samples, but varied by region. The consistent presence of yeast species and the abundance of acetic acid-generating bacteria in both experiments is consistent with our understanding of their etiological role in sour rot development.

Identification of putative promoters in 48 eukaryotic genomes on the basis of DNA free energy

Transcription is an intricate mechanism and is orchestrated at the promoter region. The cognate motifs in the promoters are observed in only a subset of total genes across different domains of life. Hence, sequence-motif based promoter prediction may not be a holistic approach for whole genomes. Conversely, the DNA structural property, duplex stability is a characteristic of promoters and can be used to delineate them from other genomic sequences. In this study, we have used a DNA duplex stability based algorithm ‘PromPredict’ for promoter prediction in a broad range of eukaryotes, representing various species of yeast, worm, fly, fish, and mammal. Efficiency of the software has been tested in promoter regions of 48 eukaryotic systems. PromPredict achieves recall values, which range from 68 to 92% in various eukaryotes. PromPredict performs well in mammals, although their core promoter regions are GC rich. ‘PromPredict’ has also been tested for its ability to predict promoter regions for various transcript classes (coding and non-coding), TATA-containing and TATA-less promoters as well as on promoter sequences belonging to different gene expression variability categories. The results support the idea that differential DNA duplex stability is a potential predictor of promoter regions in various genomes.

Lipids, hemoproteins and carotenoids in alive Rhodotorula mucilaginosa cells under pesticide decomposition – Raman imaging study

Various species of yeasts are gaining attention as producers of nutraceuticals and biofuels and due to their capacity to biodegrade chemical waste. Rhodotorula mucilaginosa is one of the most oleaginous species of yeast, an efficient de novo carotenoid producer and was reported to be capable of decomposing of organic pesticides. In this work we studied the influence of a toxic pesticide, diazinone, on production of storage (lipids) and protective (carotenoids, hemoproteins) compounds by Rh. mucilaginosa alive cells with the help of Raman imaging. It occurred that the yeast in non-oleaginous phase and aerobic environment was rich in carotenoids and their level increased significantly under incubation with diazinone, while anaerobic environment resulted in production of both carotenoids and hemoproteins and the level of the latter decreased under the influence of the pesticide. For yeasts in oleaginous phase, it was concluded that lipid production (via triggering of NAD+ accumulation and increase of the NO level) resulted in nitrosative stress leading to flavohemoprotein synthesis and was associated with the increase of the mitochondrial activity.

Ochratoxin A is degraded byYarrowia lipolytica and generates non-toxic degradation products

The mycotoxin ochratoxin A (OTA) is a common contaminant of various plant-derived foods and feeds. However, methods for complete decontamination remain to be established. Recently, biological approaches for mycotoxin removal using various species of yeast have been explored. In the present study, we investigated the efficacy of OTA degradation by the yeastYarrowia lipolytica under various conditions, altering yeast concentration, temperature, pH, and concentration of OTA in order to determine the optimal requirements of this species. At a yeast concentration of 108 cells/ml, the degradation rate was higher than that observed at any other concentration and, after 24 h, the OTA concentration was reduced to almost half of the initial level introduced to the culture. Further,Y. lipolytica cultured at 28°C showed the highest level of OTA degradation. Similarly, the culture performed optimally at a pH of 4. The initial concentration of OTA also affected the ability of the yeast to degrade OTA, with the level of degradation being the highest when the initial OTA concentration was 0.1 μg/ml. Moreover, we also tested the toxicity of the OTA biodegradation products using HepG2 cells to determine the physiological applicability of this yeast species in the food industry and observed that these products were notably less toxic than non-degraded OTA.Y. lipolytica effectively reduced natural decay incidence of grapes, and had no negative effect to the storage quality of grape fruits. Taken together, these data suggest thatY. lipolytica could be a viable OTA contamination prevention/treatment option and additional research concerning its commercial use is warranted.

Saccharomyces cerevisiae SHSY detoxifies petroleum n-alkanes by an induced CYP52A58 and an enhanced order in cell surface hydrophobicity

Environmental hydrocarbon contamination has a serious hazard to human health. Alkanes, the major component of hydrocarbons, can be consumed by various species of yeast. We previously identified a new strain SHSY of Saccharomyces cerevisiae with a remarkable ability to utilize the petroleum crude-oil (PCO) in aqueous solution. The current study demonstrated that the n-alkanes-assimilation activity of S. cerevisiae SHSY was related to an induced microsomal protein of 59kDa approximately. The identified ORF encoded a protein of 517 amino acids and shared 93% sequence identity with an alkane-inducible hydroxylase CYP52A53 isolated from Scheffersomyces stipitis CBS. It was therefore referred as CYP52A58. The catalytic activity of the recombinant CYP52A58 was confirmed by the hydroxylation of n-alkanes, it showed an optimal mono-terminal hydroxylation activity toward n-hexadecane. Moreover, the ability of the yeast to use n-alkanes was accompanied with an increasing level in cell wall mannoproteins. Two differential protein bands were detected in the mannoproteins extracted from PCO-grown yeast. In parallel, a significant increase in the fatty acids content with a high degree of unsaturation was subsequently detected in the PCO-grown yeast. This study characterizes a safe and potential microorganism to remove n-alkanes from the aquatic environment.

Pervasive Antisense Transcription Is Evolutionarily Conserved in Budding Yeast

Antisense transcription, or transcription on the opposite strand of the same genomic locus as another transcript, has been observed in many organisms, including yeast. Several antisense transcripts are known to be conserved across various species of yeast, and a few antisense transcripts are associated with functional regulation of the sense transcript. We detect antisense transcription from approximately 90% of protein-coding genes, and antisense transcription is generally associated with histone modifications indicative of a transcriptionally active state. The pattern of genome-wide antisense transcription in two species of budding yeast, Saccharomyces cerevisiae and S. paradoxus, is widely evolutionarily conserved: Antisense transcripts exhibit conserved expression levels and localization with respect to gene annotations. Regions of genes exhibiting conserved antisense transcription also show less sequence divergence than regions of genes without antisense transcription. These findings provide further support that widespread antisense transcription is functional in yeast, and expand the catalog of putative functional antisense transcripts to include nonpolyadenylated transcripts. Because antisense transcripts are less divergent in sequence than expected, they likely contain sequences important to their function.

Development and evaluation of a real-time quantitative PCR assay for detection and enumeration of yeasts of public health interest in dairy products

Yeast contamination is a problem in the food industry as a cause of spoilage. Moreover, various species of yeasts are known to be capable of causing opportunistic infections in humans. We have developed a real-time quantitative PCR (qPCR) assay to directly detect and quantify nine emerging opportunistic yeast species ( Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis, Clavispora lusitaniae, Filobasidiella neoformans, Issatchenkia orientalis, Trichosporon asahii, and Trichosporon jirovecii) in dairy product samples. We designed six primer pairs, conserved sequences of the variable D1/D2 domains of the 26S rRNA gene, to detect the yeasts and demonstrated their specificity. The qPCR assay could accurately quantify emerging opportunistic yeasts in an artificially contaminated dairy product. qPCR with the primer pairs we designed, was very sensitive and will allow producers to enumerate contaminating yeasts and identify whether they are opportunistic pathogens, in only 4 to 5 h. This assay can easily be extended to other food items and to a variety of food-monitoring initiatives.

Dynamics of indigenous yeast populations during spontaneous fermentation of wines from Mendoza, Argentina

Fermentation of wine is a complex microbial reaction, which involves the sequential development of various species of yeasts and lactic acid bacteria. Of these, yeasts are the main group responsible for alcoholic fermentation. The aim of this work was to study, under industrial conditions, the evolution of yeast populations and to describe the individual evolution of the most important yeasts during three spontaneous fermentations of Malbec musts from Argentina. This work shows the significant participation of non- Saccharomyces yeasts during spontaneous fermentation of musts, with the ubiquitous presence of three main species: Kloeckera apiculata, Candida stellata and Metschnikowia pulcherrima.

DNA probes specific for the yeast species Debaryomyces hansenii: useful tools for rapid identification

We developed a rapid and sensitive identification method for the halotolerant yeast Debaryomyces hansenii, based on the hybridization of species-specific sequences. These sequences were first identified in a survey of D. hansenii strains by random amplification of polymorphic DNA (RAPD) as giving conserved bands in all isolates tested. Two such conserved RAPD products, termed F01pro and M18pro, were cloned from the type strain CBS 767. The specificity of these probes was assessed by hybridizing them to DNA from various species of yeasts commonly found in cheese. F01pro and M18pro hybridized to the DNA of all D. hansenii var. hansenii tested, but not to DNA of other yeast species including the closely related strain of D. hansenii var. fabryii CBS 789. Hybridization patterns of F01pro and M18pro on digested genomic DNA of D. hansenii indicated that the sequences were repeated in the genome of all D. hansenii var. hansenii tested, and gave distinct polymorphic patterns. The single F01pro probe generated 11 different profiles for 24 strains by restriction fragment length polymorphism, using one restriction enzyme. F01pro represents a new type of repeated element found in fungi, useful for both identification and typing of D. hansenii and, together with M18pro, simplifies the study of this species in complex flora.

DNA probes specific for the yeast species Debaryomyces hansenii: useful tools for rapid identification.

We developed a rapid and sensitive identification method for the halotolerant yeast Debaryomyces hansenii, based on the hybridization of species-specific sequences. These sequences were first identified in a survey of D. hansenii strains by random amplification of polymorphic DNA (RAPD) as giving conserved bands in all isolates tested. Two such conserved RAPD products, termed F01pro and M18pro, were cloned from the type strain CBS 767. The specificity of these probes was assessed by hybridizing them to DNA from various species of yeasts commonly found in cheese. F01pro and M18pro hybridized to the DNA of all D. hansenii var. hansenii tested, but not to DNA of other yeast species including the closely related strain of D. hansenii var. fabryii CBS 789. Hybridization patterns of F01pro and M18pro on digested genomic DNA of D. hansenii indicated that the sequences were repeated in the genome of all D. hansenii var. hansenii tested, and gave distinct polymorphic patterns. The single F01pro probe generated 11 different profiles for 24 strains by restriction fragment length polymorphism, using one restriction enzyme. F01pro represents a new type of repeated element found in fungi, useful for both identification and typing of D. hansenii and, together with M18pro, simplifies the study of this species in complex flora.

The SPL1 tRNA splicing gene of Candida maltosa and Candida albicans.

The tRNA splicing gene SPL1-1 has been cloned and sequenced in Saccharomyces cerevisiae (Kolman and Soll, 1993). Sequence adjacent to the LEU2 gene in Candida maltosa showed some homology to the SPL1-1 gene of S. cerevisiae. This work describes the sequencing of the SPL1 tRNA splicing genes from C. maltosa and C. albicans and the analysis of these genes. Comparison of these sequences and the relationship observed between the LEU2 and SPL1 genes in these yeasts suggests that there may be some synteny amongst various species of yeasts. The coding region of the C. maltosa SPL1 region described in this work differs from previously described partial sequences in that it is a complete uninterrupted open reading frame. Two strains of C. maltosa were each shown to contain different alleles, one uninterrupted open reading frame and one disrupted open reading frame. The sequences have been deposited in the GenBank/EMBL data libraries under Accession Numbers X72940, AF000115, AF000116, AF000117, AF000118, AF000119 and AF000120. © 1998 John Wiley & Sons, Ltd.

Use of the direct epifluorescent filter technique for the enumeration of yeasts

The ability of the direct epifluorescent filter technique (DEFT) to enumerate the viable numbers of various species of yeasts was evaluated. A DEFT count could be made in less than 10 min and the DEFT counts of non-heat-treated samples agreed well with plate counts. The DEFT was unsuitable for the enumeration of yeasts in heat-treated samples because non-viable cells fluoresced orange. A double staining technique using Janus Green B and acridine orange was developed to overcome this problem. The modified DEFT enabled viable and non-viable yeasts to be differentiated in heat-treated samples of pure cultures and improved the relationship between the DEFT count and plate count. The method proved to be of little value, however, for use with beverage products because of unreliable staining patterns.

Simple and small-scale breakdown of yeast

A simple and small-scale method for the preparation of homogenate from yeast was developed. The principle of this new method involves the shaking of a small amount of yeast-cell suspension with glass beads on a tower-shaped mixer. When this method is used the cells in 1 ml of cell suspension are broken down and 14 samples can be simultaneously processed under controlled conditions. The degree of cell breakdown, the amount of soluble protein liberated from the cells, and the increase in each enzyme activity in prepared homogenate correlated to the shaking time: maximum values were obtained at 20 min. Enzyme activities in the homogenate were equivalent to or higher than that procured with former methods. This new method is applicable to various species of yeasts.

Determination of cellular fatty acid compositions of various yeasts by gas-liquid chromatography.

The cellular fatty acid composition of 51 cultures of various species of yeasts was determined by gas-liquid chromatography. Analysis was done with a fused-silica gas-liquid chromatography capillary column, with resolution of all components including mono-, di-, and tri-unsaturated 18-carbon acids. The cultures were placed into one of four distinct gas-liquid chromatography groups on the basis of large quantitative differences in fatty acids. Group I contained only Saccharomyces species and group II only Torulopsis glabrata. Most Candida species were placed into group III, and group IV contained only basidiomycetous yeasts.

Yeast Cell-Wall Glucans

Publisher Summary This chapter describes the present state of knowledge on the structure and metabolism of the related glucan components of yeast cell walls. Many of the earlier structural studies involved commercial samples of pressed baker's yeast and, although these enabled the main structural features to be identified, they were of limited value from a metabolic point of view. With recent improvements in polysaccharide fractionation and in the methods of structural analysis, it is now possible to use smaller samples of yeast from laboratory-scale cultures as the experimental material, and hence, to relate the changes in cell–wall structure with cell growth. The structural analysis of glucan preparations isolated from various species of yeast is also described, where all of the constituent monosaccharide residues are assumed to have the D-configuration. The chapter discusses the synthesis of glucan from nucleoside diphosphate sugar compounds by a variety of yeast enzyme preparations, and lastly it also deals with the physiological control of the glucan content of yeast cell walls during various conditions of growth.

Enhancement of amphotericin B activity by a series of compounds related to phenolic antioxidants

Earlier studies showed that several common phenolic antioxidants enhanced the inhibitory action of amphotericin B against various species of yeasts. In the present work a search was made for compounds chemically related to the antioxidants which possess similar activity, greater water solubility, and which would present less of a potential toxicological hazard in the evaluation of drug-antioxidant combinations in vivo. A number of compounds showed these characteristics, the most interesting and potentially useful of which were L-dopa (L-β-3,4-dihydroxyphenylalanine) and dopamine (3,4-dihydroxyphenylethylamine).

Anaerobic growth and formation of respiration-deficient mutants of various species of yeasts

Yeast Saccharomyces cerevisiae has often been used in the study of biogenesis and function of mitochondria taking advantage of the abilities of this species to grow under anaerobic conditions and to give rise to cytoplasmic respiration-deficient mutants. It has been usually assumed that both abilities are related to the high fermentation capacity of this yeast which can furnish energy for growth under conditions when oxidative phosphorylation is not functioning. However, this assumption has not yet been subjected to unequivocal experimental tests. Little is known of how other yeast species behave in this respect except that many species of ‘petite negative’ yeasts do not form cytoplasmic respirationdeficient mutants [ 1,2]. The use of other yeast species may help to clarify this problem and also provide new experimental possibilities for the study of mitochondria not encountered with the common baker’s or brewer’s yeasts. By employing a number of different yeast species this paper shows that the ability of a cell to grow under strictly anaerobic conditions is not related to its respiration or fermentation capacities and that these capacities are also not directly responsible for the ability of some species to form respirationdeficient mutants.

Cell wall components of various species of yeasts

Cell walls were obtained from three species of yeasts, Torulopsis aeris, Oospora suaveolens and Geotrichum lactis, and their components were analysed. The monosaccharide constituents found were glucose and mannose in T. aeris, and the same, plus galactose, in O. suaveolens and G. lactis. The only amino sugar in all three cases is glucosamine. An increase in total nitrogen and hexosamine was observed, together with a decrease in total sugars, as the morphological characteristics approached those of filamentous fungi. The mannan content of the wall of O. suaveolens was directly related to the age of the culture. Three polysaccharide-protein complexes were isolated from each species. Glucose, mannose and galactose were present in quantities which varied from fraction to fraction in each case, but not in the strict proportions which have been found by other authors. There is no qualitative difference to be observed in the amino acid content of each fraction, the twelve most common in protein being present. Our analyses do not suggest that these fractions represent, as such, structural units in the cell wall. Examination of one fraction revealed that the original form of the cell remains in some cases. In these cases a large amount of hexosamine was present, which suggests that the fraction concerned contains the chitin of the original cell wall.

Oxidative assimilation and endogenous respiration of Rhodotorula graminis.

SummaryResults of the 14C-distribution studies suggest that equilibria (steady state conditions) are maintained between the various constituents of the cells, at least during the early stages of endogenous respiration and before death becomes a major factor. The loss of nitrogen from the cells as NH3 would result in some shift in internal conditions. The results indicate that the oxidative assimilatory and endogenous respiratory activities of the oxidative yeast R. graminis are similar to those reported for fermentative yeasts and for bacteria. The results of the RQ studies and those on the amino acid pool and on NH3 production indicate that amino acids are a major endogenous substrate for this organism. Carbohydrate, which is an endogenous substrate for various species of yeast, does not appear to act as such to a marked extent for R. graminis.

PRODUCTION OF YEAST AND MOLD PROTOPLASTS BY TREATMENT WITH THE STREPZYME OF MICROMONOSPORA AS.

Using phase microscopy, the authors made studies of the formation and properties of spherical protoplasts of the organisms Candida utilis, Oospora suaveolens, and Geotrichum lactis, produced by digestion of the cell walls in isotonic medium with a lytic preparation obtained from the filtrates of the growth medium of Micromonospora AS. The susceptibility of various species of yeast and molds to cell wall digestion and further liberation of protoplasts was variable. MgSO4 (0.8 to 1.0 M final concentration) was a satisfactory stabilizer for producing osmotically sensitive spherical bodies. On dilution, these fragile structures lysed immediately. The naked protoplasts were able to grow, as indicated by changes in morphology. On prolonged incubation abnormal cells were formed. Reversion to normal cells was observed but was very rare. Details of the emergence of the Oospora suaveolens protoplasts were described. Protoplasts were also prepared from a variety of bacteria.