MALDI-TOF MS Supplementary database for species identification employing the yeast diversity encountered on southern Brazil grapes

The study of grape microflora is of interest when autochthonous yeasts, which are related to typical wine characteristics, are intended to be used in winemaking. The election of matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS) as the first method for yeast identification was based on its accuracy and rapidity compared to alternative laboratory protocols for identification. The aims of this study are to consolidate the MALDI-TOF MS Supplementary database for environmental yeasts already constructed, to expand it through the addition of standard spectra of not included yeast species, and to discuss the grape microflora encountered in Southern Brazil. A total of 358 strains, isolated from grape berries, were submitted to protein profiling employing Biotyper and Supplementary database. Molecular biology techniques were used as alternatives to identify 6.4% of strains not promptly designated by protein profiling. These strains corresponded to the species Candida californica, Zygoascus meyerae, Candida akabanensis, Candida azyma, and Hanseniaspora vineae. The MALDI-TOF MS spectra of the identified species were added to Supplementary database. The presented results strengthen the need for further expansion of the mass spectra database to broaden its microbiological application.     

From grape berries to wine: population dynamics of cultivable yeasts associated to “Nero di Troia” autochthonous grape cultivar

The aim of this work was to study the biodiversity of yeasts isolated from the autochthonous grape variety called “Uva di Troia”, monitoring the natural diversity from the grape berries to wine during a vintage. Grapes were collected in vineyards from two different geographical areas and spontaneous alcoholic fermentations (AFs) were performed. Different restriction profiles of ITS–5.8S rDNA region, corresponding to Saccharomyces cerevisiae, Issatchenkia orientalis, Metschnikowia pulcherrima, Hanseniaspora uvarum, Candida zemplinina, Issatchenkia terricola, Kluyveromyces thermotolerans, Torulaspora delbrueckii, Metschnikowia chrysoperlae, Pichia fermentans, Hanseniaspora opuntiae and Hanseniaspora guilliermondii, were observed. The yeast occurrences varied significantly from both grape berries and grape juices, depending on the sampling location. Furthermore, samples collected at the end of AF revealed the great predominance of Saccharomyces cerevisiae, with a high intraspecific biodiversity. This is the first report on the population dynamics of ‘cultivable’ microbiota diversity of “Uva di Troia” cultivar from the grape to the corresponding wine (“Nero di Troia”), and more general for Southern Italian oenological productions, allowing us to provide the basis for an improved management of wine yeasts (with both non-Saccharomyces and Saccharomyces) for the production of typical wines with desired unique traits. A certain geographical-dependent variability has been reported, suggesting the need of local based formulation for autochthonous starter cultures, especially in the proportion of the different species/strains in the design of mixed microbial preparations.     

Yeasts in <Emphasis Type="Italic">Hevea brasiliensis</Emphasis> latex

Yeast abundance and species diversity in the latex of rubber tree Hevea brasiliensis (Willd. ex Juss.) Müll. Arg., on its green leaves, and in soil below the plant were studied. The yeasts present in the fresh latex in numbers of up to 5.5 log(CFU/g) were almost exclusively represented by the species Candida heveicola. This species was previously isolated from Hevea latex in China. In the course of natural modification of the latex (turned from liquid to solid form), yeast diversity increased, while yeast abundance decreased. The yeasts in thickened and solidified latex were represented by typical epiphytic and ubiquitous species: Kodamea ohmeri, Debaryomyces hansenii, Rhodotorula mucilaginosa, and synanthropic species Candida parapsilosis and Cutaneotrichosporon arboriformis. The role of yeasts in latex modification at the initial stages of succession and their probable role in development of antifungal activity in the latex are discussed.     

Yeast population of the Kindo Peninsula lichens

Yeast abundance and species diversity in the lichens collected at the Kindo Peninsula (Karelia) were studied. A total of 14 lichen species analyzed belonged to the genera Bryoria, Cladonia, Hypogymnia, Icmadophila, Nephroma, Peltigera, and Ramalina. Abundance of cultured yeasts in lichens was intermediate between soil and phyllosphere. The average yeast number on lichens was ~2.5 × 10³ CFU/g, while it exceeded 8 × 10³ CFU/g on plants and reached only 1 × 10³ CFU/g in soil. Yeast population of different parts of Cladonia lichens was found to vary significantly in abundance, species diversity, and community structure. The highest yeast abundance and diversity were revealed in the growth zone. Fifteen yeast species were isolated from lichens, including 6 basidiomycetous and 9 ascomycetous ones. Unlike soils and plants, yeast population of lichens consisted mainly of ascomycetous species, with predominance of Candida sphagnicola and anamorphous yeasts of the genus Dothiora. These results show that yeasts from different taxonomic and ecological groups are a necessary component of lichens; conditions favoring the preservation and development of specific yeast communities differing from the typical soil and phyllosphere yeast complexes are formed in the lichens of northern taiga forests.     

Identification of yeasts isolated from raffia wine (<Emphasis Type="Italic">Raphia hookeri</Emphasis>) produced in Côte d’Ivoire and genotyping of <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> strains by PCR inter-delta

Raffia wine is a traditional alcoholic beverage produced in several African countries where it plays a significant role in traditional customs and population diet. Alcoholic fermentation of this beverage is ensured by a complex natural yeast flora which plays a decisive role in the quality of the final product. This present study aims to evaluate the distribution and the diversity of the yeast strains isolated in raffia wine from four sampling areas (Abengourou, Alépé, Grand-Lahou and Adzopé) in Côte d’Ivoire. Based on the D1/D2 domain of the LSU rDNA sequence analysis, nine species belonging to six genera were distinguished. With a percentage of 69.5 % out of 171 yeast isolates, Saccharomyces cerevisiae was the predominant species in the raffia wine, followed by Kodamaea ohmeri (20.4 %). The other species isolated were Candida haemulonii (4.1 %), Candida phangngensis (1.8 %), Pichia kudriavzevii (1.2 %), Hanseniaspora jakobsenii (1.2 %), Candida silvae (0.6 %), Hanseniaspora guilliermondii (0.6 %) and Meyerozyma caribbica (0.6 %). The molecular characterization of S. cerevisiae isolates at the strain level using the PCR-interdelta method revealed the presence of 21 profiles (named I to XXI) within 115 isolates. Only four profiles (I, III, V and XI) were shared by the four areas under study. Phenotypic characterization of K. ohmeri strains showed two subgroups for sugar fermentation and no diversity for the nitrogen compound assimilations and the growth at different temperatures.     

Yeasts in Antarctic soils

The yeast flora of 126 soil samples from the Ross Dependency of Antarctica was examined and compared with that of eight samples from East Greenland. Fifty-two Antarctic samples contained yeasts, in numbers ranging from 5 to over 100,000/g; species isolated belonged to the generaDebaryomyces, Cryptococcus, Candida, Trichosporon andRhodotorula. Nearly all isolates ofCandida were obligate psychrophils; they belonged toCandida scottii, C. nivalis, C. gelida andC. frigida. Duplicate samples, taken at the same site within a few yards of one another, contained the same size and kind of yeast populations. Although not all samples which contained plants (algae, lichens or mosses) contained yeasts, almost all samples which contained yeasts contained plants. There was no correlation between yeast population and the pH of the sample, nor between yeast populations and the presence of vertebrate animals. The samples from East Greenland, which were from an area sufficiently warm and moist to support growth of higher plants, all contained yeasts, in numbers from 200 to 56,000/g. Species isolated were similar to those from Antarctic material.     

The yeast <Emphasis Type="Italic">Candida railenensis</Emphasis> in the fruits of English oak (<Emphasis Type="Italic">Quercus robur</Emphasis> L.)

The cotyledons of whole intact acorns were shown to contain yeasts; their number increased sharply before acorn germination. The yeasts in the cotyledons are mainly represented by one species, Candida railenensis, with the number in the germinating cotyledons reaching 10⁷ CFU/g. After germination or exocarp destruction, the cotyledons were colonized by the usual epiphytic and litter yeasts Cryptococcus albidus, Rhodotorula glutinis, and Cystofilobasidium capitatum.     

The diversity of culturable yeasts in the phylloplane of rice in Thailand

One hundred and fifty-six yeast strains were obtained by the enrichment technique from the phylloplanes of 85 rice leaf samples collected from seven provinces in Thailand. On the basis of the D1/D2 domain of the large subunit rRNA gene sequence analysis, 156 strains were identified as 34 known species in 18 genera consisting of 25 species in 13 genera of the phylum Ascomycota and nine species in five genera of the phylum Basidiomycota. The species in the phylum Ascomycota comprised 24 species in 12 genera of the order Saccharomycetales and one species viz. Yarrowia lipolytica in Saccharomycetales incertae sedis. The 24 species viz. Candida glabrata in the Nakaseomyces clade of Saccharomycetaceae, Candida jaroonii, Candida membranifaciens and Candida terebra in the Yamadazyma clade of Debaryomycetaceae, Candida pseudolambica in the Pichia clade of Pichiaceae, Candida ruelliae in the Metschnikowia clade of Metschnikowiaceae, and three unaffiliated clade Candida species (Candida catenulata, Candida rugosa and Candida tropicalis); Clavispora lusitaniae, Kodamaea ohmeri, Metschnikowia koreensis and Metschnikowia lopburiensis in Metschnikowiaceae; Cyberlindnera fabianii, Cyberlindnera rhodanensis and Wickerhamomyces ciferrii in Wickerhamomycetaceae; Debaryomyces nepalensis, Meyerozyma caribbica, Meyerozyma guilliermondii, Millerozyma koratensis, and Yamadazyma mexicanum in Debaryomycetaceae; Pichia kudriavzevii in Pichiaceae; and Lachancea thermotolerans in Saccharomycetaceae. The species in Basidiomycota viz. Cryptococcus flavescens, Cryptococcus laurentii, Cryptococcus aff. laurentii and Cryptococcus rajasthanensis in the Tremellales lineage, Bulleromyces clade, Tremellales, Tremellomycetes, Agaricomycotina; Pseudozyma antarctica and Pseudozyma aphidis in Ustilaginales, Ustilaginomycetes, Ustilaginomycotina; Rhodotorula taiwanensis and Sporobolomyces blumeae in Sporidiobolales, Microbotryomycetes, Pucciniomycotina; and Trichosporon asahii in Trichosporonales, Tremellomycetes, Agaricomycotina. The most prevalent species was R. taiwanensis with a 23 % frequency of occurrence followed by Candida tropicalis (16 %) and Cryptococcus fabianii (12 %).     

Identification of yeasts during alcoholic fermentation of <Emphasis Type="Italic">tchapalo</Emphasis>, a traditional sorghum beer from Côte d’Ivoire

This study investigated the diversity and dynamics of yeasts involved in alcoholic fermentation of a traditional sorghum beer from Côte d’Ivoire, tchapalo. A total of 240 yeast strains were isolated from fermenting sorghum wort inoculated with dry yeast from two geographic regions of Côte d’Ivoire (Abidjan and Bondoukou). Initial molecular identification to the species level was carried out using RFLP of PCR-amplified internal transcribed spacers of rDNA (ITS1-5.8S-ITS2). Ten different profiles were obtained from the restriction of PCR products with the three endonucleases HaeIII, CfoI and HinfI. Sequence analysis of the D1/D2 domain of the 26S rDNA and the ACT1 gene allowed us to assign these groups to six different species: Saccharomyces cerevisiae-like, Candida tropicalis, Pichia kudriavzevii, Pichia kluyveri, Kodamaea ohmeri and Meyerozyma caribbica. The most frequent species associated with tchapalo fermentation was S. cerevisiae-like (87.36%), followed by C. tropicalis (5.45%) and M. caribbica (2.71%). S. cerevisiae-like strains were diploid heterozygotes and exhibited three to four nucleotides divergence from the type strain in the D1/D2 domain and several indels in the more discriminant sequence of the intron of the ACT1 gene. During the process, the yeast species isolated and their frequencies varied according to the geographic origin of the dry yeast. The occurrence of some species was sporadic and only two non-Saccharomyces species were found in the final product.     

Endophytic yeasts in <Emphasis Type="Italic">Malus domestica</Emphasis> and <Emphasis Type="Italic">Pyrus communis</Emphasis> fruits under anthropogenic impact

Yeast abundance and species diversity on the surface and in inner tissues of Malus domestica and Pyrus communis fruits under high anthropogenic impact in the city of Moscow (Russia) were studied. Results demonstrated that abundance of epiphytic yeasts on the fruits increased gradually, reaching the maximum of 3.2 × 10⁴ CFU/g on mature fruits. During summer, abundance of endophytes did not change significantly (variation near 2.5 × 10³ CFU/g) until complete maturation, while in September their numbers increased to 10⁴ CFU/g. Basidiomycetous yeasts (Filobasidium wieringae, F. magnum, Rhodotorula glutinis, and Rhodosporidiobolus colostri) predominated on the fruit surface. Ascomycetous species were the most diverse group inside the fruits, which quantitatively increased through maturation. It was found that the share of opportunistic species Candida parapsilosis in internal tissues was significant during the entire period of fruit formation and development under anthropogenic impact in the city. Specific properties of epiphytic and endophytic yeast communities developing in natural ecological niches under synanthropic conditions and anthropogenic impact are discussed.     

Yeast Communities of the Moscow City Soils

Yeast abundance and diversity were studied in the soils (topsoil) of Moscow city: urban soils under lawn vegetation and close to the areas of household waste disposal, as well as in zonal soddy-podzolic soils (retisols) in parks (Losiny Ostrov and Izmailovo). The numbers of soil yeasts were similar in all studied urban biocenoses (on average ~3.5 × 10³ CFU/g). From all studied soils, 54 yeast species were isolated. The highest yeast diversity was found in the soils adjacent to the areas of household waste storage. Soils from different urban sites were found to have different ratios of ascomycetous and basidiomycetous yeasts: basidiomycetes predominated in urban soils under lawn vegetation, while in the areas close to the waste disposal sites their share was considerably lower. The differences between the studied urban soils were also found in the structure of soil yeast complexes. In urban soils with high anthropogenic impact, the isolation frequency of clinically important yeast species (Candida parapsilosis, C. tropicalis, Diutina catenulata, and Pichia kudriavzevii) was as high as 35% of all studied samples, while its share in the community was 17%. The factors responsible for development of specific features of yeast communities in various urban soils are discussed in the paper.     

Usefulness of the Non-conventional <Emphasis Type="Italic">Caenorhabditis elegans</Emphasis> Model to Assess <Emphasis Type="Italic">Candida</Emphasis> Virulence

Invasive candidiasis is caused mainly by Candida albicans, but other Candida species have increasing etiologies. These species show different virulence and susceptibility levels to antifungal drugs. The aims of this study were to evaluate the usefulness of the non-conventional model Caenorhabditis elegans to assess the in vivo virulence of seven different Candida species and to compare the virulence in vivo with the in vitro production of proteinases and phospholipases, hemolytic activity and biofilm development capacity. One culture collection strain of each of seven Candida species (C. albicans, Candida dubliniensis, Candida glabrata, Candida krusei, Candida metapsilosis, Candida orthopsilosis and Candida parapsilosis) was studied. A double mutant C. elegans AU37 strain (glp-4;sek-1) was infected with Candida by ingestion, and the analysis of nematode survival was performed in liquid medium every 24 h until 120 h. Candida establishes a persistent lethal infection in the C. elegans intestinal tract. C. albicans and C. krusei were the most pathogenic species, whereas C. dubliniensis infection showed the lowest mortality. C. albicans was the only species with phospholipase activity, was the greatest producer of aspartyl proteinase and had a higher hemolytic activity. C. albicans and C. krusei caused higher mortality than the rest of the Candida species studied in the C. elegans model of candidiasis.     

Assessment of endophytic yeast diversity in rice leaves by a culture-independent approach

Endophytic microorganisms inhabit internal plant tissues in the host plant without causing any symptoms or negative effects. Although the diversity of endophytes has been evaluated by both culture-dependent and culture-independent methods, less information is available on yeast communities. Therefore, in this study a culture-independent method was used to examine endophytic yeasts associated with rice leaves based on the large subunit of ribosomal DNA using a semi-nested PCR technique. Sequence analysis indicated that the colonization frequency and the relative species frequency (RF) of endophytic yeast phylotypes were 0.41 and 0.06, respectively, and the majority of the yeast phylotypes were basidiomycetous yeasts. The phylotypes were designated as five known species (Cryptococcus victoriae, Debaryomyces hansenii, Debaryomyces vindobonensis, Meyerozyma guilliermondii and Pseudozyma antarctica), together with seventeen phylotypes closest to Candida metapsilosis, Cryp. foliicola, Cryp. laurentii, Pseudozyma abaconensis, Pseudozyma aphidis and Trichosporon asahii, among which some could be novel species. The most prevalent phylotypes were those closest to Cryp. foliicola (47.5 % RF) followed by D. hansenii (22.8 % RF) and P. antarctica (16.8 % RF). The presence of the phylotypes related to species known for their potential applications as biocontrol agents and plant growth promoting hormone producers suggests that they may have valuable applications. In addition, our findings revealed the occurrence of novel phylotypes at high frequency, which should encourage extensive studies to discover novel yeast species and to understand their roles in the rice leaves.     

Yeasts from peat in a tropical peat swamp forest in Thailand and their ability to produce ethanol,indole-3-acetic acid and extracellular enzymes

This study aimed to isolate and identify yeasts from peat in To Daeng peat swamp forest in southern of Thailand, and to investigate their ability to produce ethanol from glucose and xylose and to produce indole-3-acetic acid (IAA) and extracellular enzymes. A total of 65 yeast strains were obtained from 15 peat samples using an enrichment technique, and 61 strains were identified to be five species belonging to the phylum Ascomycota, namely Cyberlindnera subsufficiens, Debaryomyces fabryi, Meyerozyma guilliermondii, Saturnispora diversa and Schwanniomyces polymorphus var. africanus, and five species of the phylum Basidiomycota, namely Cryptococcus taiwanensis pro tem, Cutaneotrichosporon mucoides, Papiliotrema flavescens, Papiliotrema laurentii and Rhodotorula mucilaginosa. Four strains were unidentified and require further analysis. They differed from the type strain of P. flavescens by two nucleotide substitutions in the D1/D2 region of the LSU rRNA gene and nine nucleotide substitutions in the ITS region. R. mucilaginosa was the most prevalent yeast species, followed by S. polymorphus var. africanus, Cy. subsufficiens and D. fabryi. None of the yeast strains obtained in this study were able to ferment xylose to ethanol, but all ascomycetous yeast strains produced ethanol from glucose in a range of 9.0–58.0 g/L, with Cy. subsufficiens DMKU-YNB42-1 producing the highest ethanol concentration. A total of 62 strains produced IAA in a range of 9.0 to 66.9 mg/L, with the highest IAA produced by R. mucilaginosa DMKU-Y33-A. Investigation of the production of cellulases, xylanase, pectinase, amylase, protease and lipase revealed that all 65 yeast strains produced at least one extracellular enzyme, a lipase.     

Characterization of extracellular yeast peptide factors and their stress-protective effect on probiotic lactic acid bacteria

Protective effect of the extracellular peptide fraction (reactivating factors, RF) produced by yeasts of various taxonomic groups (Saccharomyces cerevisiae, Kluyveromyces lactis, Candida utilis, and Yarrowia lipolytica) on probiotic lactic acid bacteria (LAB) Lactobacillus casei, L. acidophilus, and L. reuteri under bile salt (BS)-induced stress was shown. RF of all yeasts were shown to be of peptide nature; the active component of the S. cerevisiae RF was identified as a combination of low-molecular polypeptides with molecular masses of 0.6 to 1.5 kDa. The protective and reactivating effects of the yeast factors were not species-specific and were similar to those of the Luteococcus japonicus subsp. casei RF. In BS-treated cells of the tester bacteria, a protective effect was observed after 10-min preincubation of the LAB cell suspension with yeast RF: the number of surviving cells (CFU) was 2 to 4.5 times higher than in the control. The reactivating effect was observed when RF was added to LAB cell suspensions not later than 15 min after stress treatment. It was less pronounced than the protector effect, with the CFU number 1 to 3 times that of the control. Both the protector and the reactivating effects were most pronounced in the S. cerevisiae and decreased in the row C. utilis > K. lactis > Y. lipolytica. The efficiency of protective action of yeast RF was found to depend on the properties of recipient LAB cells, with the L. casei strain being most sensitive to BS treatment. In both variants, the highest protective effect of RF (increase in the CFU number) was observed for L. acidophilus, while the least pronounced one was observed for L. casei. The reasons for application of the LAB strains combining high stress resistance and high response to stress-protecting metabolites, including RF factors, as probiotics, is discussed.     

Characterization of the fungal flora of dolo,a traditional fermented beverage of Burkina Faso,using MALDI-TOF mass spectrometry

A cross-sectional study was conducted in Bobo-Dioulasso, Burkina Faso, to identify the yeast diversity associated with the manufacture of dolo, a traditional fermented beverage of Burkina Faso. From sixty specimens spread onto chromogenic medium plates, sixty-two strains were isolated then identified using MALDI-TOF analysis. Seven yeast species were identified, Saccharomyces cerevisiae (39%) followed by Pichia manshurica (18%) being the most frequent. Forty-three percent of the samples contained Candida species, notably Candida albicans. In conclusion, the combined use of a chromogenic medium and MALDI-TOF analysis reveals a higher diversity in yeast species present in the dolo than previously thought.     

Molecular genetic polymorphism of soil yeasts of the genus <Emphasis Type="Italic">Williopsis</Emphasis> from Taiwan Island

Comparative molecular genetic study of Williopsis yeasts isolated in different world regions reveals some peculiarities of species content in Taiwan. Some Williopsis yeasts may represent novel species. In Taiwan, four of the five known Williopsis species are documented: W. saturnus, W. suaveolens, W. mrakii, and W. subsufficiens. The W. saturnus yeasts predominate in Taiwanese soils, while W. suaveolens is more frequently isolated in Europe.     

Screening and genetic identification of acidic and neutral protease-producing yeasts strains by 26S rRNA gene sequencing

Protease enzymes (proteases), particularly those produced by microorganisms, play very important roles in industry, due to their diverse applications. Considering the richness of microbial diversity in nature, a good chance always exists that proteases more suitable, with better properties for commercial application, may be discovered while screening novel microorganisms from local environments. In this study, 94 yeasts were isolated from different natural sources collected from the Abha region, Kingdom of Saudi Arabia, to determine extracellular protease production and activity. Among them, 23 isolates (24.46%) showed protease activity using a casein hydrolysis test. Of these, five isolates (21.74%) were selected and identified as the best protease producers by exhibiting the largest clearance zones around colonies. A 26S rRNA gene D1/D2 domain sequence alignment, comparison, and phylogenetic analysis of our study yeasts to published D1/D2 domain rRNA gene sequences from GenBank, identifies the isolates as Rhodotorula mucilaginosa KKU-M12c, Cryptococcus albidus KKU-M13c, Pichia membranifaciens KKU-M18c, Hanseniaspora uvarum KKU-M19c, and Candida californica KKU-M20c. The influence of varying pH (4.0–9.0) on the yield and activity of the proteases was investigated using 0.5% (w/v) casein as a substrate, to detect optimum pH values for yeast extracellular protease production. Enzyme activity was measured using qualitative and quantitative assays. Results show all of the study yeasts secreting protease enzyme at all tested pH levels, with the exception of pH 9.0. This indicates that none of the five yeasts are alkaline protease producers. Maximum protease activity (187 U/mL) was observed in strain H. uvarum KKU-M19c at pH 6.0 (only), indicating that strain KKU-M19c only produces neutral protease. The other four yeast isolates, R. mucilaginosa KKU-M12c, C. albidus KKU-M13c, P. membranifaciens KKU-M18c, and C. californica KKU-M20c, produced both acidic (at pH 4.0) and neutral (at pH 6.0 and 7.0) proteases. Strain C. californica KKU-M20c was found to be the best acidic and neutral protease producer (138 U/mL at pH 4.0, and 185 U/mL at pH 7.0). This is the first report of the discovery and isolation of local, powerful yeasts producing acidic and neutral protease enzymes from the Abha region, Kingdom of Saudi Arabia.     

Diversity and characterization of cultivable oleaginous yeasts isolated from mangrove forests

A total of 198 yeasts were isolated from 140 samples collected from 7 mangrove forests in 4 provinces of Thailand, and were found to belong to 30 genera, 45 described species and at least 12 undescribed species based on their 26S rRNA (D1/D2 domain) gene sequence. The most prevalent species was Candida tropicalis, followed by Candida pseudolambica and Rhodosporidium paludigena. Lipid accumulation, as determined by Nile red staining, of the isolated yeasts revealed that 69 and 18 strains were positive and strongly positive, respectively, while quantitative analysis of the intracellular lipid accumulated in the latter indicated that 10 of these strains, Pseudozyma tsukubaensis (YWT7-2 and YWT7-3), Rhodotorula sphaerocarpa (YWW6-1 and SFL14-1SF), Saitozyma podzolica (YWT1-1, NS3-3 and NS10-2), Prototheca zopfii var. hydrocarbonea OMS6-1 and Prototheca sp. (YMTW3-1 and YMTS5-2), were oleaginous. In this study we found that under nitrogen depletion condition (155 C/N ratio) Pseudozyma tsukubaensis YWT7-2 accumulated the highest level of intracellular lipid at 32.4% (w/w, dry cell weight), with a broadly similar fatty acid composition to that in palm oil.     

Molecular identification of yeast,lactic and acetic acid bacteria species during spoilage of tchapalo,a traditional sorghum beer from Côte d’Ivoire

Yeasts, lactic and acetic acid bacteria are responsible of microbial spoilage of alcoholic beverages. However species involved in deterioration of sorghum beer produced in Côte d’Ivoire has not been investigated. This study was carried out to identify species of yeast, LAB and AAB during spoilage of tchapalo in order to define the best strategy for beer preservative. Thus, a total of 210 yeasts, LAB and AAB were isolated from samples of tchapalo stored at ambient temperature and at 4 °C for 3 days. Based on PCR–RFLP of the ITS region and the sequencing of D1/D2 domain, yeast isolates were assigned to seven species (Saccharomyces cerevisiae, Candida tropicalis, Rhodotorula mucilaginosa, Trichosporon asahii, Kluyveromyces marxianus, Meyerozyma guilliermondii and Trichosporon coremiiforme). During the storage at ambient temperature and at 4 °C, S. cerevisiae was the predominant species (>?76%). Excepted R. mucilaginosa, occurrence of non-Saccharomyces species was sporadic. LAB species detected in fresh samples using molecular methods were Pediococcus acidilactici, Lactobacillus paracasei, Lb. curvatus, Lb. fermentum and Weisssella paramesenteroides. P. acidilactici was the dominant species (47.8%) followed by Lb. paracasei (17.5%). W. paramesenteroides and Lb. fermentum were not detected during the spoilage at ambient temperature while at 4 °C W. paramesenteroides and Lb. paracasei have not been detected. For AAB, the species found were Acetobacter pasteurianus sub paradoxus and Acetobacter cerevisiae. These species were common to all samples during spoilage and A. pasteurianus sub paradoxus was the most frequently detected.