(GTG)5 MSP-PCR fingerprinting as a technique for discrimination of wine associated yeasts?

Enhancing Mezcal Production Efficiency by Adding an Inoculant of Native Saccharomyces cerevisiae to a Standardized Fermentation Must

All traditional mezcal producers use artisan methods to produce mezcal. The low technological development in the elaboration processes results in low yield and high residual sugar concentration. First, this work optimized the concentration of initial sugars and yeast-assimilable nitrogen (YAN) in Agave durangensis juice fermentation at the laboratory level. A yield near 0.49 g EtOH/g sugar and a productivity of 1.54 g EtOH/L*h was obtained with an initial sugar concentration of 120 g/L and a YAN concentration of 0.227 g/L. Only Saccharomyces cerevisiae was found after 24 h of incubation at laboratory level, using MALDI-TOF identification. Agave durangensis heads crushed by the artisan process were used to test the inoculant performance. A mezcal yield of 11.6 kg agave/L of mezcal was obtained using the S cerevisiae inoculant and nitrogen addition, which was significantly different (p < 0.05) from other treatments. The population dynamics during fermentation were analyzed through isolation and identification using MALDI-TOF. Several yeast species (Pichia kluyveri, Torulaspora delbrueckii, Zygosaccharomyces bailii, and Saccharomyces cerevisiae) were found at the beginning of fermentation. Nonetheless, only S. cerevisiae was found at the end of fermentation. The implantation of the inoculant used was confirmed through the comparative analysis of amplification patterns of the GTG5 microsatellite of the strains identified as S. cerevisiae, finding that the inoculated strain proportion was greater than 80% of the yeast population. A technological alternative to increase the efficiency of the process is combining the addition of YAN and the inoculation of the native S. cerevisiae, which was isolated from artisan alcoholic fermentation of agave to produce mezcal.

Exploring the Diversity and Ecological Dynamics of Palm Leaf Spotting Fungi-A Case Study on Ornamental Palms in Portugal

Palm trees (Arecaceae) are among the most popular ornamental plants worldwide. Despite extensive research on the fungi associated with Arecaceae, the diversity and ecological dynamics of fungi affecting ornamental palms remain poorly studied, although they have significant impact on palm health and economic value. Furthermore, while research on palm fungal diversity has traditionally focused on tropical assemblages, ornamental palms in temperate climates offer a unique opportunity to explore the diversity of palm fungi in non-native habitats. The present study conducted a preliminary assessment of the diversity and ecology of potential phytopathogenic fungi associated with foliar lesions on various ornamental palm host species in Portugal, combining morphological examination, PCR-based genomic fingerprinting, and biodiversity data analysis. The examination of 134 foliar lesions sampled from 100 palm trees resulted in a collection of 2064 palm leaf spotting fungi (PLSF), representing a diverse fungal assemblage of 320 molecular operational taxonomic units (MOTUs) across 97 genera. The overall fungal community composition revealed a distinct assemblage dominated by Neosetophoma, Alternaria, Phoma, and Cladosporium, with a profusion of infrequent and rare taxa consistent with a logseries distribution. Significantly positive co-occurrence (CO) patterns among prevalent and uncommon taxa suggest potential synergistic interactions enhancing fungal colonisation, persistence, and pathogenicity. The taxonomic structures of the PLSF contrasted markedly from tropical palm fungi, especially in the prevalence of pleosporalean coelomycetes of the Didymellaceae and Phaeosphaeriaceae, including recently introduced or not previously documented genera on Arecaceae. This novel assemblage suggests that climatic constraints shape the structure of palm fungal communities, resulting in distinctive temperate and tropical assemblages. In addition, the fungal assemblages varied significantly across palm host species, with temperate-native palms hosting more diverse, coelomycete-enriched communities. The present findings highlight foliar lesions as hyperdiverse microhabitats harbouring fungal communities with intricate interactions and a complex interplay of climatic, host, and ecological factors. With climate change altering environmental conditions, the identification of fungi thriving in or inhabiting these microhabitats becomes crucial for predicting shifts in pathogen dynamics and mitigating future fungal disease outbreaks. Understanding these complex ecological dynamics is essential for identifying potential phytopathogenic threats and developing effective management strategies for the health and sustainability of ornamental plants.

Fungal Identifier (FId): An Updated Polymerase Chain Reaction-Restriction Fragment Length Polymorphism Approach to Ease Ascomycetous Yeast Isolates' Identification in Ecological Studies

Culturomics has been temporarily exceeded by the advent of omics approaches such as metabarcoding and metagenomics. However, despite improving our knowledge of microbial population composition, both metabarcoding and metagenomics are not suitable for investigating and experimental testing inferences about microbial ecological roles and evolution. This leads to a recent revival of culturomics approaches, which should be supported by improvements in the available tools for high-throughput microbial identification. This study aimed to update the classical PCR-RFLP approach in light of the currently available knowledge on yeast genomics. We generated and analyzed a database including more than 1400 ascomycetous yeast species, each characterized by PCR-RFLP profiles obtained with 143 different endonucleases. The results allowed for the in silico evaluation of the performance of the tested endonucleases in the yeast species' identification and the generation of FId (Fungal Identifier), an online freely accessible tool for the identification of yeast species according to experimentally obtained PCR-RFLP profiles.

Wickerhamiella lachancei f.a. sp. nov., a novel ascomycetous yeast species isolated from flowers of Lantana camara in India

Two isolates representing a novel species of the genus Wickerhamiella were obtained in India from nectar of flowers of Lantana camara, an ornamental exotic species native to Central and South America. Phylogenetic analyses of the D1/D2 domain of the 26S large subunit (LSU) rRNA gene, internal transcribed spacer (ITS) region, and physiological characteristics, supported the recognition of the novel species, that we designate Wickerhamiella lachancei sp. nov (MycoBank no. MB851709), with MCC 9929T as the holotype and PYCC 10003T as the isotype. Considering pairwise sequence similarity, the type strain of the novel species differs from the type strain of the most closely related species, Wickerhamiella drosophilae CBS 8459T, by 16 nucleotide substitutions and two gaps (3.9 % sequence variation) in the D1/D2 region (560 bp compared) and 28 nucleotide substitutions and five gaps (7.22 % sequence variation) in the ITS region (444 bp compared).

Non-Saccharomyces Are Also Forming the Veil of Flor in Sherry Wines

Biological ageing is an essential process for obtaining some distinctive Sherry wines, such as Fino and Manzanilla. It occurs after the fermentation of the grape must due to the appearance of a biofilm on the surface of the wine called “veil of flor”. Yeasts belonging to the Saccharomyces cerevisiae species mainly comprise such biofilm. Although other species have also been found, these have been traditionally considered spoilage. Indeed, it has even been hypothesised that they may not be able to form biofilm on their own under such conditions. In the present work, four different non-Saccharomyces yeasts isolated from barrels in the Jerez area under biological ageing have been characterised through their physiological abilities, including extracellular enzymatic and biofilm-forming capabilities. Results showed not only a surprising ethanol tolerance, above 15.5% in all cases, but also a significant degree of extracellular enzyme production, highlighting the urease and proteolytic activities found in Pichia manshurica, as well as lipolytic activity in Pichia kudriavzevii, Pichia membranifaciens and Wicherhamomyces anomalus. As a conclusion, these non-Saccharomyces could be very interesting in the oenological field, beyond improving the organoleptic characteristics as well as technological features in these wines.

Wild Saccharomyces Produced Differential Aromas of Fermented Sauvignon Blanc Must

Nine Saccharomyces strains, previously isolated from vineyards in Southern Brazil, were used as starter cultures in fermentations of Sauvignon Blanc (SB) must at laboratory scale, to study inter-strain differences in aroma profiles. The molecular profiles differentiated the following isolates from the reference strain (SC2048), which is typically used in wine production: 06CE, 11CE, 33CE, 01PP, 12M, 13PP, 26PP, 28AD, and 41PP. Under the same conditions, each of these strains produced different concentrations and combinations of metabolites, which significantly influenced the aroma of the fermented SB must. Volatile compounds such as octanoic acid, diethyl succinate, and ethyl lactate were associated with the strains 26PP, 41PP, 01PP, and 12M, while strains 33CE, 28AD, 13PP, and 06CE were associated with the production of ethyl acetate and 1-hexanol. Strain 06CE produced 592.87 ± 12.35 µg/L 1-hexanol. In addition, the olfactory activity values (OAVs; we considered only values >1) allowed us to evaluate the participation of each compound in the aroma of the final fermented SB. In conclusion, the selected wild strains are promising candidates for improving the regional characteristics of wine.

Nakazawaea odontotermitis f.a., sp. nov., a novel yeast isolated from the gut of Odontotermes horni in India

Three strains, SMT1.3, SMT1.10, and SMT2.2, representing a novel asexual ascomycetous yeast species, were isolated from the gut of a termite Odontotermes horni in Maharashtra, India. Phylogenetic analyses of the LSU, ITS, and SSU sequences revealed that they belonged to the genus Nakazawaea, with N. siamensis as the closest relative. The new species differed from the type strain of N. siamensis (DMKU-RK467^T) by 11 substitutions in the D1/D2 region of the large subunit (LSU) rRNA gene and by 8 substitutions and one gap in the small subunit (SSU) rRNA gene. Notable biochemical and physiological differences were also observed between N. siamensis and the new species. Hence, the species Nakazawaea odontotermitis f.a., sp. nov. is proposed. The type strain is SMT1.3 ^T (MTCC 13,105 = NFCCI 5011 = PYCC 9153). GenBank accession numbers of the LSU, ITS and SSU sequences of Nakazawaea odontotermitis f.a., sp. nov. are MZ234240, MZ234239, and OK384663. The MycoBank number is MB 841926.

Microbial Consortia Involved in Traditional Sicilian Sourdough: Characterization of Lactic Acid Bacteria and Yeast Populations

Sourdough is one of the oldest starters traditionally used for making baked goods, offering several advantages to the sensory, rheology, and shelf life of final products. The present study investigated, for the first time, the microbiota of spontaneously fermented Maiorca dough samples collected from bakeries located in Sicily (Italy). Four sourdough samples (M1, M2, M3, and M4), were produced using Triticum vulgare Host. var. albidum Koern (Maiorca grain) were subjected to LAB and yeasts isolation and identification at the species level. The in-depth characterization of the lactobacilli population revealed that Lactiplantibacillus plantarum and Levilactobacillus brevis unquestionably dominated the Maiorca sourdough ecosystem. Concerning the yeasts community, high species diversity was found. Saccharomyces cerevisiae and Wickerhamomyces anomalus were the most frequently isolated species. In addition, Torulaspora delbrueckii, Pichia kluyveri, Candida boidinii, and Candida diddensiae were also detected. Investigations on both pro-technological and functional traits of the isolated strains could lead to the selection of starters for the production of baked goods.

Nectar Yeast Community of Tropical Flowering Plants and Assessment of Their Osmotolerance and Xylitol-Producing Potential

Floral nectar is colonised by microbes, especially yeasts which alter the scent, temperature, and chemical composition of nectar, thereby playing an essential role in pollination. The yeast communities inhabiting the nectar of tropical flowers of India are not well explored. We isolated 48 yeast strains from seven different tropical flowering plants. Post MSP-PCR-based screening, 23 yeast isolates and two yeast-like fungi were identified, which belonged to 16 species of 12 genera viz. Candida (2 species), Aureobasidium (2 species), Metschnikowia (2 species), Meyerozyma (1 species), Saitozyma (1 species), Wickerhamomyces (1 species), Kodamaea (2 species), Pseudozyma (1 species), Starmerella (1 species), Hanseniaspora (1 species), Rhodosporidiobolus (1 species), Moesziomyces (1 species), and two putative novel species. All yeast strains were assessed for their osmotolerance abilities in high salt and sugar concentration. Among all the isolates, C. nivariensis (SRA2.2, SRA1.1 and SRA2.1), M. caribbica (SRA4.8 and SRA4.6), S. flava SRA4.2, and M. reukaufii SRA3.2 showed significant growth in high concentrations of sugar (40-50% glucose), as well as salt (12-15% NaCl). All 25 strains were also screened for their ability to utilise xylose to produce xylitol. Meyerozyma caribbica was the most efficient xylitol producer, wherein three strains of this species (SRA4.6, SRA4.1, and SRA4.8) generated 18.61 to 21.56 g l^-1 of xylitol, with 0.465-0.539 g g^-1 yields. Through this study, we draw attention towards the tropical floral nectar as a potential niche for the isolation of diverse, osmotolerant, and xylitol-producing yeasts. Such osmotolerant yeasts have potential applications in food industries and biofuel production.

Compost as an untapped niche for thermotolerant yeasts capable of high-temperature ethanol production

Efficient bioethanol production from lignocellulosic biomass requires thermotolerant yeasts capable of utilizing multiple sugars, tolerating inhibitors and fermenting at high temperatures. In this study, 98 thermotolerant yeasts were isolated from nine compost samples. We selected 37 yeasts that belonged to 11 species; 31 grew at 45°C; 6 strains grew at 47°C, while 9 yeasts could utilize multiple sugars. Many yeast isolates showed high ethanol production in the range of 12-24 g l^-1 , with fermentation efficiencies of 47-94% at 40°C using 5% glucose. Kluyveromyces marxianus CSV3.1 and CSC4.1 (47°C), Pichia kudriavzevii CSUA9.3 (45°C) produced 21, 22 and 23 g l^-1 of ethanol with efficiencies of 83, 87 and 90%, respectively, using 5% glucose. Among these yeasts, K. marxianus CSC4.1 and P. kudriavzevii CSUA9.3 exhibited high tolerance against furfural, 5-HMF, acetic acid and ethanol. These two strains produced high amounts of ethanol from alkali-treated RS, with 84 and 87% efficiency via separate hydrolysis and fermentation; 76 and 74% via simultaneous saccharification and fermentation at 47 and 45°C, respectively. Therefore, this study demonstrates compost as a potential anthropogenic niche for multiple sugar-utilizing, inhibitor-tolerant ethanologenic yeasts suitable for high-temperature ethanol production via SHF of rice straw.

Exopolysaccharides Producing Lactic Acid Bacteria in Wine and Other Fermented Beverages: For Better or for Worse?

Lactic acid bacteria (LAB) from fermented beverages such as wine, cider and beer produce a wide range of exopolysaccharides (EPS) through multiple biosynthetic pathways. These extracellular polysaccharides constitute key elements for bacterial species adaptation to such anthropic processes. In the food industry, LAB polysaccharides have been widely studied for their rheological, functional and nutritional properties; however, these have been poorly studied in wine, beer and cider until recently. In this review, we have gathered the information available on these specific polysaccharide structure and, biosynthetic pathways, as well as the physiology of their production. The genes associated with EPS synthesis are also presented and compared. Finally, the possible role of EPS for bacterial survival and spread, as well as the risks or possible benefits for the winemaker and the wine lover, are discussed.

Bacteria and yeasts associated to Colonial cheese production chain and assessment of their hydrolytic potential

Abstract Different types of microorganisms are important in cheese-making because of the contributions their metabolism offers during the process. Few microorganisms present in Colonial cheese are known, in addition to the ones that are introduced to kick-start the processes or the ones that are associated with infections or poisonings. This study aimed to identify, by MALDI-TOF and/or DNA sequencing, the bacteria and yeasts isolated from samples collected in the main stages of Colonial cheese production, i.e., a type of cheese produced in the southern region of Brazil. The lytic capacity of these microorganisms at 5 °C and 30 °C was also evaluated. The 58 bacterial strains were distributed in 10 species among the genera Bacillus, Citrobacter, Klebsiella, Lactococcus, Paenibacillus, Staphylococcus and Raoutella. From the 13 yeasts strains analyzed, three species were identified as following: Candida pararugosa; Meyerozyma guilliermondii; and Rhodotorula mucilaginosa. In three yeasts isolates it was possible to identify only the genus Candida sp. and Trichosporon sp. The species L. lactis (48%) and M. guilliermondii (46%) were, respectively, the predominant bacteria and yeasts species isolated. The highest microbial lytic activity observed was at 30 °C. Lipase activity on isolates was proportionally more observed with yeasts and proteolytic activity with bacteria. Lower caseinase and lipase activity was observed at 5 °C, demonstrating the importance of refrigeration in controlling microbial activity. This research highlighted the cultivation of some microorganisms that are part of the Colonial cheese microbiota as well as that several of them can hydrolyze various compounds present in milk and that could be associated with its maturation or, in uncontrolled circumstances, could be the cause of product deterioration.

Dataset of Nile Red Fluorescence Readings with Different Yeast Strains, Solvents, and Incubation Times

We used Nile red to estimate lipid content in oleaginous yeasts using a high-throughput approach. We measured the fluorescence intensity of Nile red using different solvents, yeast strains, and incubation times in optimized excitation/emission wavelengths. The data show the relative fluorescence units (RFU) for Nile red excitation, using 1× PBS, 1× PBS and 5% v/v isopropyl alcohol, 50% v/v glycerol, culture medium A-gly broth, and A-gly broth supplemented with 5% v/v DMSO. In addition, we showed the RFU for the Nile red dye for different oleaginous and non-oleaginous yeast strains, such as Meyerozyma guilliermondii BI281A, Yarrowia lipolytica QU21 and Saccharomyces cerevisiae MRC164. Other measurements of lipid accumulation kinetics were shown for the above and additional yeast strains. These datasets provide the guidelines to obtain the optimal solvent system and the minimal interaction time for the Nile red dye to enter in the cells and obtain a stable readout.

The utility of iPBS retrotransposons markers to analyze genetic variation in yeast

Yeasts are one of the main organisms in the food industry and effective components of many ecosystems. The method for identifying and detecting certain yeast species or strains is a crucial step for the food industry and should be simple, reliable, fast, and inexpensive. In our study, inter-priming binding sites (iPBS) retrotransposon marker system was employed to elucidate the genetic variability at intraspecies and interspecies levels among 112 yeast strains belonging to eight species previously obtained from fermented foods. The molecular identification of yeast strains was firstly confirmed by sequencing the D1/D2 domain of the 26S rRNA. The eight selected retrotransposon-based primers produced 278 bands, all of which were polymorphic with an average of 34.75 polymorphic fragments per primer. The averages of polymorphism information contents and the resolving power values for the iPBS marker system were 0.23 and 10.11, respectively. The genetic parameters within each yeast species obtained from iPBS markers were observed as; the percentage of polymorphic loci for each species ranging from 19.23% to 71.21%, Nei's gene diversity from 0.085 to 0.228, while Shannon's information index values ranging from 0.125 to 0.349. The value of gene flow (0.09) and genetic variation among the populations (0.85) showed higher genetic variation among the species. UPGMA analyses demonstrated considerable genetic variability in the yeast strains, clustered them according to their species, and revealed the intraspecific variation. Each of the selected iPBS primer provided enough species-discrimination. Present evaluations suggest the utility of iPBS marker system to estimate the genetic variation of yeast strains. This study is a preliminary point for further studies on the identification methodology, and population genetics of yeast species having importance in the food industry with iPBS markers.

Dominant yeasts associated to mango (Mangifera indica) and rose apple (Syzygium malaccense) fruit pulps investigated by culture-based methods

The biotechnological potential of yeasts associated to different habitats in Colombia has been poorly studied, especially the yeasts associated with different plant structures. Fruit pulps are interesting substrates mainly for the growth of yeast species, that can positively affect the productivity and quality of some bioeconomic species. Therefore, the objective of this study was to identify the dominant yeast species associated with mango and rose apple fruit pulps in Cali, Colombia. A total of 90 isolates were obtained, which were grouped considering their colony morphology. The D1/D2 domain of the large ribosomal RNA gene (LSU rRNA gene) or internal transcribed spacer (ITS) 1, ribosomal gene 5.8S and ITS 2 (ITS) regions of one to several representative isolates from each group was sequenced and compared with type strains for identification. The species Hanseniaspora thailandica, H. opuntiae and Clavispora lusitaniae were reported as shared by both fruits, specific for rose apple (H. uvarum, Pichia terricola, Rhodosporidiobolus ruineniae and Candida albicans), or for Mango (Meyerozyma caribbica, M. guilliermondii, C. natalensis, Aureobasidium pullulans, Pichia sp., Saturnispora diversa and C. jaroonii). Two morphotypes were not identified at the taxonomic level of species and were reported as candidates for new species, belonging to the genera Wickerhamomyces and Pichia.

Evaluation of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for differentiation of Pichia kluyveri strains isolated from traditional fermentation processes

RATIONALE

Non-Saccharomyces yeasts are widespread microorganisms that nowadays have gained importance for their ability to produce volatile compounds which in alcoholic beverages improve aromatic complexity and therefore the overall quality. Their rapid identification and differentiation in fermentation processes is vital for timely decision making.

METHODS

A total of 19 strains of Pichia kluyveri isolated from mezcal, tejuino and cacao fermentations were analyzed with rep-PCR fingerprinting using the primer (GTG)₅ and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) on a Microflex LT mass spectrometer using Biotyper 3.1 software (Bruker Daltonics).

RESULTS

The comparative analysis between MS spectra and rep-PCR patterns obtained from these strains showed a high similarity between both methods. However, minimal differences between the obtained rep-PCR and MALDI-TOF MS clusters could be observed, especially by the presence and/or absence of one or more discriminating peaks even when they have similarities in their main spectra projection, observing that isolates from the same fermentative process were grouped into the same sub-cluster based on their MALDI-TOF MS profiles.

CONCLUSIONS

The data shown suggests that MALDI-TOF MS is a promising alternative technique for rapid, reliable and cost-effective differentiation of native yeast strains isolated from different traditional fermented foods and beverages.

Evolution of Yeast Consortia during the Fermentation of Kalamata Natural Black Olives upon Two Initial Acidification Treatments

The objective of this study was to elucidate the yeast consortia structure and dynamics during Greek-style processing of Kalamata natural black olives in different brine solutions. Olives were subjected to spontaneous fermentation in 7% (w/v) NaCl brine solution (control treatment) or brine acidified with (a) 0.5% (v/v) vinegar, and (b) 0.1% (v/v) lactic acid at the onset of fermentation. Changes in microbial counts, pH, acidity, organic acids, sugars, and alcohols were analyzed for a period of 187 days. Yeast consortia diversity was evaluated at days 4, 34, 90, 140, and 187 of fermentation. A total of 260 isolates were characterized at sub-species level by rep-PCR genomic fingerprinting with the oligo-nucleotide primer (GTG)5. The characterization of yeast isolates at species level was performed by sequencing of the D1/D2 domain of 26S rRNA gene. Results showed that yeasts dominated the process presenting a relatively broad range of biodiversity composed of 11 genera and 21 species. No lactic acid bacteria (LAB) or Enterobacteriaceae could be enumerated after 20 and 10 days of fermentation, respectively. The dominant yeast species at the beginning were Aureobasidium pullulans for control and vinegar acidification treatments, and Candida naeodendra for lactic acid treatment. Between 34 and 140 days the dominant species were Candida boidinii, Candida molendinolei and Saccharomyces cerevisiae. In the end of fermentation the dominant species in all processes were C. boidinii and C. molendinolei, followed by Pichia manshurica and S. cerevisiae in lactic acid acidification treatment, P. manshurica in vinegar acidification treatment, and Pichia membranifaciens in control fermentation.

Evaluation of fingerprinting techniques to assess genotype variation among Zygosaccharomyces strains

Molecular typing techniques are key tools in surveillance of food spoilage yeasts, in investigations on intra-species population diversity, and in tracing selected starters during fermentation. Unlike previous works on strain typing of Zygosaccharomyces spoilage species, here Zygosaccharomyces mellis and the Zygosaccharoymces rouxii complex yeasts, which include Z. rouxii, Zygosaccharomyces sapae, and a mosaic lineage (ML) of putatively hybrids, were evaluated by three typing methods for intra- and inter-species resolution. Overall these yeasts are relevant for food fermentation and spoilage, but are quite difficult to discriminate at strain and species level as they evolved by reticulation. A pool of 76 strains from different sources were typed by M13 and (GTG)₅ MSP-PCR fingerprinting and PCR-RFLP of ribosomal intergenic spacer region (IGS). We demonstrated that M13 overcame (GTG)₅ fingerprinting to group Z. sapae, Z. rouxii, Z. mellis and the ML isolates in congruent distinct clusters. Even if (GTG)₅ primer yielded a number of DNA fingerprints comparable with those obtained by M13 primer, it failed to discriminate Z. sapae, Z. mellis and Z. rouxii at species level. Clustering of IGS RFLP patterns obtained with three endonucleases produced groups congruent with species assignment and highlighted intra-species diversity similar to that observed by M13 fingerprinting. However, IGS PCR amplification failed for 14 ML and 6 Z. mellis strains under the experimental conditions tested here, indicating that this marker could be less easy to use in fast typing protocol. Finally, our results posit that the genetic diversity within Z. sapae and Z. mellis could be shaped by isolation source. The information generated in this study would facilitate the monitoring of these yeasts during food processing and storage, and provides preliminary evidences about Z. sapae and Z. mellis intra-species diversity.

The Oleaginous Yeast Meyerozyma guilliermondii BI281A as a New Potential Biodiesel Feedstock: Selection and Lipid Production Optimization

A high throughput screening (HTS) methodology for evaluation of cellular lipid content based on Nile red fluorescence reads using black background 96-wells test plates and a plate reader equipment allowed the rapid intracellular lipid estimation of strains from a Brazilian phylloplane yeast collection. A new oleaginous yeast, Meyerozyma guilliermondii BI281A, was selected, for which the gravimetric determination of total lipids relative to dry weight was 52.38% for glucose or 34.97% for pure glycerol. The lipid production was optimized obtaining 108 mg/L of neutral lipids using pure glycerol as carbon source, and the strain proved capable of accumulating oil using raw glycerol from a biodiesel refinery. The lipid profile showed monounsaturated fatty acids (MUFA) varying between 56 or 74% in pure or raw glycerol, respectively. M. guilliermondii BI281A bears potential as a new biodiesel feedstock.

South Brazilian wines: culturable yeasts associated to bottled wines produced in Rio Grande do Sul and Santa Catarina

A comprehensive understanding of the presence and role of yeasts in bottled wines helps to know and control the organoleptic quality of the final product. The South Region of Brazil is an important wine producer, and the state of "Rio Grande do Sul" (RS) accounts for 90% of Brazilian wines. The state of "Santa Catarina" (SC) started the production in 1975, and is currently the fifth Brazilian producer. As there is little information about yeasts present in Brazilian wines, our main objective was to assess the composition of culturable yeasts associated to bottled wines produced in RS and SC, South of Brazil. We sampled 20 RS and 29 SC bottled wines produced between 2003 and 2011, and we isolated culturable yeasts in non-selective agar plates. We identified all isolates by sequencing of the D1/D2 domain of LSU rDNA or ITS1-5.8 S-ITS2 region, and comparison with type strain sequences deposited in GenBank database. Six yeast species were shared in the final product in both regions. We obtained two spoilage yeast profiles: RS with Zygosaccharomyces bailii and Pichia membranifaciens (Dekkera bruxellensis was found only in specific table wines); and SC with Dekkera bruxellensis and Pichia manshurica. Knowledge concerning the different spoilage profiles is important for winemaking practices in both regions.

Exploration of genetic and phenotypic diversity within Saccharomyces uvarum for driving strain improvement in winemaking

The selection and genetic improvement of wine yeast is an ongoing process, since yeast strains should match new technologies in winemaking to satisfy evolving consumer preferences. A large genetic background is the necessary starting point for any genetic improvement programme. For this reason, we collected and characterized a large number of strains belonging to Saccharomyces uvarum. In particular, 70 strains were isolated from cold-stored must samples: they were identified and compared to S. uvarum strains originating from different collections, regarding fermentation profile, spore viability and stress response. The results demonstrate a large biodiversity among the new isolates, with particular emphasis to fermentation performances, genotypes and high spore viability, making the isolates suitable for further genetic improvement programmes. Furthermore, few of them are competitive with Saccharomyces cerevisiae and per se, suitable for wine fermentation, due to their resistance to stress, short lag phase and fermentation by-products.

A New Strategy to Evaluate Technical Efficiency in Hospitals Using Homogeneous Groups of Casemix : How to Evaluate When There is Not DRGs?

The public health system has restricted economic resources. Because of that, it is necessary to know how the resources are being used and if they are properly distributed. Several works have applied classical approaches based in Data Envelopment Analysis (DEA) and Stochastic Frontier Analysis (SFA) for this purpose. However, if we have hospitals with different casemix, this is not the best approach. In order to avoid biases in the comparisons, other works have recommended the use of hospital production data corrected by the weights from Diagnosis Related Groups (DRGs), to adjust the casemix of hospitals. However, not all countries have this tool fully implemented, which limits the efficiency evaluation. This paper proposes a new approach for evaluating the efficiency of hospitals. It uses a graph-based clustering algorithm to find groups of hospitals that have similar production profiles. Then, DEA is used to evaluate the technical efficiency of each group. The proposed approach is tested using the production data from 2014 of 193 Chilean public hospitals. The results allowed to identify different performance profiles of each group, that differs from other studies that employs data from partially implemented DRGs. Our results are able to deliver a better description of the resource management of the different groups of hospitals. We have created a website with the results ( bioinformatic.diinf.usach.cl/publichealth ). Data can be requested to the authors.

Fast method for identifying inter- and intra-species Saccharomyces hybrids in extensive genetic improvement programs based on yeast breeding

AIMS

The present work proposes a two-step molecular strategy to select inter- and intra-species Saccharomyces hybrids obtained by spore-to-spore mating, one of the most used methods for generating improved hybrids from homothallic wine yeasts.

METHODS AND RESULTS

As low spore viability and haplo-selfing are the main causes of failed mating, at first, we used colony screening PCR (csPCR) of discriminative gene markers to select hybrids directly on dissection plate and discard homozygous diploid colonies arisen from one auto-diploidized progenitor. Then, pre-selected candidates were submitted to recursive streaking and conventional PCR in order to discriminate between the hybrids with stable genomic background and the false-positive admixtures of progenitor cells both undergone haplo-selfing. csPCRs of internal transcribed spacer (ITS) 1 or 2, and the subsequent digestion with diagnostic endonucleases HaeIII and RsaI, respectively, were efficient to select six new Saccharomyces cerevisiae × Saccharomyces uvarum hybrids from 64 crosses. Intragenic minisatellite regions in PIR3, HSP150, and DAN4 genes showed high inter-strain size variation detectable by cost-effective agarose gel electrophoresis and were successful to validate six new intra-species S. cerevisiae hybrids from 34 crosses.

CONCLUSIONS

Both protocols reduce significantly the number of massive DNA extractions, prevent misinterpretations caused by one or both progenitors undergone haplo-selfing, and can be easily implemented in yeast labs without any specific instrumentation.

SIGNIFICANCE AND IMPACT OF THE STUDY

The study provides a method for the marker-assisted selection of several inter- and intra-species yeast hybrids in a cost-effective, rapid and reproducible manner.