Kloeckera Apiculata Research Articles

NaCl inhibits Geotrichum citri-aurantii growth by inducing lipid droplets accumulation and enhances the biocontrol efficacy of Kloeckera apiculata 34-9

Decays resulting from infections by Geotrichum citri-aurantii cause a significant reduction in citrus postharvest quality and marketable yield. In the present work, 0.8 mol · L-1 NaCl of Generally Recognized as Safe (GRAS) salts were identified to have complete inhibition activity to G. citri-aurantii in vitro and in vivo. An inhibitory mechanism study showed that 0.1 mol · L-1 NaCl changed the expression of six genes (Gci002087, Gci003354, Gci000013, Gci000394, Gci003505 and Gci004433) in target of rapamycin (TOR) pathway, thus inducing a large number of lipid droplets (LDs) accumulation with TEM observations and staining. In vivo, 0.1 mol · L-1 NaCl could raise up the activities of CAT, PAL, PPO and cellulase which hence to strengthen the ability of resistance tolerance of citrus. In addition, NaCl not only accelerated the growth of the biocontrol yeast Kloeckera apiculata strain 34-9, but also increased the expression level of adhesin-encoding genes and biofilm-formation encoding gene (34-9 - 3691). Finally, the storage experiments in 3 months demonstrated that the combination of NaCl and the yeast 34-9 could keep fresh, reduce decay and prolong its shelf-life, thus implying that the combination of biocontrol strain and GRAS salts has been explored as a promising alternative to synthetic fungicides.

Pullulan-based coatings carrying biocontrol yeast mixed with NaCl to control citrus postharvest disease decays

The decline in postharvest citrus quality due to fungal infections necessitates innovative packaging solutions. This study presents a pullulan-based edible film (PBYFs) with biocontrol yeasts, designed to dissolve in both liquid and soil. This film is capable of enveloping entire citrus fruits, effectively managing postharvest diseases, and extending their shelf life. The formulation of PBYFs includes NaCl 0.1 M, Kloeckera apiculata 34–9 at 1.0 × 107 CFU mL−1, pullulan 3 % w/v, SA 0.5 % w/v, and glycerin 1 % w/v. Our experiments, conducted on eight citrus varieties, demonstrated that PBYFs significantly reduced the occurrence of green and blue molds, sour rot, and anthracnose in vivo. Moreover, PBYFs-coated fruits exhibited an extended shelf life without compromising the quality parameters such as weight loss, TSS (total soluble solids), TA (titratable acidity), VC (vitamin C), or the accumulation of off-flavor volatiles. This research presents a promising approach for creating scalable, cost-effective, and environmentally sustainable biodegradable antifungal packaging systems for citrus fruits.

Potential of Endophytic Microorganisms in Fermentative Processes Using Agro-Industrial Waste as Substrates

This study investigated the potential of endophytic microorganisms in fermentative processes using agro-industrial residues as substrates. The aim was to explore sustainable biotechnological methods for producing valuable compounds from waste. Endophytic microorganisms were isolated from strawberry, lychee, and tangerine and used in fermentative processes with passion fruit, guava, and pineapple residues. Key methods included isolating and screening potent aroma-producing microorganisms, identifying them using MALDI-TOF MS, and analyzing volatile compounds by GC-MS. The results identified 37 endophytic microorganisms, with Kloeckera apiculata presenting the greatest aromatic potential. Fermentation with agro-industrial residues produced significant volatile compounds, identifying 27, 23, and 22 compounds from passion fruit, pineapple, and guava residues, respectively. The main conclusions highlighted the high production of ethyl acetate and 2-phenylethyl acetate, which contributed to fruity and floral aromas. The novelty of this study lies in the use of endophytic microorganisms isolated from tropical fruits to biotransform agro-industrial waste into high-value aromatic compounds, offering economic and environmental benefits. This research is significant, as it proposes a sustainable approach to valorize waste and produce natural aroma compounds through biotechnological processes.

Microbiological analysis of wine produced in the laboratory using pineapple and watermelon fruits fermented by Kloeckera apiculata

This research focuses on the microbiological analysis of wine produced in a laboratory using pineapple and watermelon fruits fermented by Kloeckera apiculata. The study aimed at evaluating the microbial composition, including yeast, bacteria, and mold, and the physicochemical properties of the wine during the fermentation process. The experiment was conducted using two batches of fruit, pineapple, and watermelon, separately fermented using Kloeckera apiculata. Samples were collected at different stages of fermentation and analyzed for microbial composition, pH, alcohol content, and total acidity. The yeasts, mold, and bacteria present were enumerated and isolated by spread plate techniques and incubated at room temperatures for 24h. Resultant colonies were enumerated and identified by a standard protocol. The results showed that Kloeckera apiculata dominated the microbial population during the fermentation process. No mold was isolated due to the low level of oxygen present in the fermentor. Three bacteria species were identified and confirmed during the fermentation to be Lactobacillus plantarum, Lactobacillus brevis, and Pediococcus species which are non-pathogenic bacteria and did not constitute any threat to health rather added a sour taste to the wine and also decreased the pH of the wine. The wine produced from pineapple had a higher alcohol content and lower acidity than the wine produced from watermelon. These findings demonstrate the potential of Kloeckera apiculata for the production of wine using tropical fruits and highlight the importance of microbiological analysis in the quality control of wine production.

Effects of simultaneous inoculation of non-Saccharomyces yeasts and Saccharomyces cerevisiae jiangnan1# on overall quality, flavor compounds, and sensory analysis of huangjiu

Non-Saccharomyces yeast (NSY) co-fermentation with Saccharomyces cerevisiae has been widely used to produce high-quality fermented alcoholic beverages. In this study, we evaluated the feasibility of 24 NSY strains belonging to 13 different genera co-fermentation with S. cerevisiae jiangnan1# in huangjiu brewing. Different fermentation trials were set up and the effects on huangjiu fermentation were also analyzed. Results indicated that simultaneous inoculation could realize the application of NSY, while the appropriate proportion of S. cerevisiae and NSY (1:1 or 1:10) showed differential effects. Finally, three types of NSY strains (Zygosaccharomyces rouxii Non-Sc11, Kloeckera apiculata Non-Sc17, and Candida tropicalis Non-Sc21) with high ethanol content (>16% vol), moderate concentration of higher alcohols (<400 mg/L, 14% vol), higher production of esters (P < 0.05), and lower organic acid (P < 0.05) were obtained ultimately. The sensory evaluation demonstrated that using no less than one kind of the three NSY strains in simultaneous fermentation with S. cerevisiae jiangnan1# (1:1) resulted in sensory diversity of new huangjiu styles. In addition, the method for evaluation and application of NSY in co-fermentation with S. cerevisiae jiangnan1# in huangjiu brewing had been established for the first time, which could be directly applied in industrial production of huangjiu.

Kloeckera apiculata promotes the healing of potato tubers by rapidly colonizing and inducing phenylpropanoid metabolism and reactive oxygen species metabolism

As a biocontrol yeast, Kloeckera apiculata exhibits excellent control for various postharvest diseases in fruit and vegetables. However, it is still unclear how K. apiculata influences the healing of potato tubers. The effect of K. apiculata treatment on the healing of wounded tuber was investigated by observing the population dynamics of K. apiculata and the formation of the closing layer. Furthermore, this study analyzed the activities and product contents of phenylpropanoid metabolism and reactive oxygen species metabolism at wounds. The results showed that K. apiculata effectively colonized wounds and peaked at 7 d of healing. Tubers treated with K. apiculata exhibited higher key enzyme activities and more production contents of phenylpropanoid metabolism. K. apiculata activated NADPH oxidase and superoxide dismutase, which ascended contents of superoxide anion and hydrogen peroxide. Besides, K. apiculata accelerated suberin polyphenolic and lignin formation and reduced weight loss of wounded tubers and disease index of tubers inoculated with Fusarium sulfureum. Above all, K. apiculata positively affected healing by colonizing and profiling rapidly and inducing phenylpropanoid metabolism and reactive oxygen species metabolism at wounds.

Effects and possible modes of action of Kloeckera apiculata for controlling Penicillium expansum in apples

Kloeckera apiculata is a yeast strain with excellent biocontrol capacity. The strain can effectively control a variety of postharvest diseases in fruit. However, the effect of the yeast control on blue mold caused by Penicillium expansum in apples and its related mechanisms have rarely been reported. In this study, the colony diameter and mycelial weight of P. expansum were reduced with varied doses of K. apiculata treatment. Compared with controls, the colony diameter and weight of P. expansum mycelial treated with 1 × 108 cell/mL of yeast were 63 % and 70 % lower, respectively. The original yeast culture treatment exhibited the highest inhibition, followed by the culture filtrate, while inactivated culture filtrate displayed no significant inhibitory effect. Results from scanning electron microscopy demonstrated that yeast parasitizes mycelial surfaces, thereby reducing survival and damaging mycelial integrity. Moreover, yeast rapidly colonized apple wounds, reducing decay and lesion diameter. The yeast treatment upregulated the activity of superoxide dismutase, catalase, peroxidase, polyphenol oxidase, and phenylalanine ammonia-lyase, and increased total phenols, flavonoids, and lignin content of the fruit. K. apiculata may directly inhibit the growth of P. expansum through competition for nutrients and space, and via parasitism. The yeast could also induce resistance against P. expansum by eliciting antioxidant enzymes and phenylpropanoid metabolism.

Chromosome Genome Sequencing and Comparative Transcriptome-Based Analyses of Kloeckera apiculata 34-9 Unveil the Potential Biocontrol Mechanisms Against Citrus Green Mold.

Biological control is an environmentally friendly, safe, and replaceable strategy for disease management. Genome sequences of a certain biocontrol agent could lay a solid foundation for the research of molecular biology, and the more refined the reference genome, the more information it provides. In the present study, a higher resolution genome of Kloeckera apiculata 34-9 was assembled using high-throughput chromosome conformation capture (Hi-C) technology. A total of 8.07 M sequences of K. apiculata 34-9 genome was anchored onto 7 pesudochromosomes, which accounting for about 99.51% of the whole assembled sequences, and 4,014 protein-coding genes were annotated. Meanwhile, the detailed gene expression changes of K. apiculata 34-9 were obtained under low temperature and co-incubation with Penicillium digitatum treatments, respectively. Totally 254 differentially expressed genes (DEGs) were detected with low temperature treatment, of which 184 and 70 genes were upregulated and downregulated, respectively. Some candidate genes were significantly enriched in ribosome biosynthesis in eukaryotes and ABC transporters. The expression of gene Kap003732 and Kap001595 remained upregulated and downregulated through the entire time-points, respectively, indicating that they might be core genes for positive and negative response to low temperature stress. When co-incubation with P. digitatum, a total of 2,364 DEGs were found, and there were 1,247 upregulated and 1,117 downregulated genes, respectively. Biosynthesis of lysine and arginine, and phenylalanine metabolism were the highest enrichment of the cluster and KEGG analyses of the co-DEGs, the results showed that they might be involved in the positive regulation of K. apiculata 34-9 response to P. digitatum. The completeness of K. apiculata 34-9 genome and the transcriptome data presented here are essential for providing a high-quality genomic resource and it might serve as valuable molecular properties for further studies on yeast genome, expression pattern of biocontrol system, and postharvest citrus storage and preservation.

Research of antifungal effects on some essential oils with tube dilution

The aim of study to investigate inhibition effects of cinnamic acid (volatile compound of cinnamon), limonene (essential oil of lemon) and eugenol (essential oil of clove, cinnamon) on Metschnikowia fructicola, Candida oleophila, Schisosaccharomyces pombe, Saccharomyces uvarum and Kloeckera apiculata. In this study, tube dilution method was used. Among eugenol, limonene and cinnamic acid, it was found that cinnamic acid has the most inhibition effect with low concentrations (%2.8, %3.84, %4.36, %5,4) at tube dilution methods. Also it was found that test yeast have different resistance against test materials.

OENOLOGICAL CHARACTERISTICS AND VINIFICATION RESULTS OF THE YEAST OF MALAGOUSIA GRAPE ISOLATED IN GREECE

Malagousia grapes, selected from 5 different PGI Greek zones, in 3 different growing seasons (2018-2019, 2019-2020, 2020-2021) were collected in the stage of technological maturity. Quantity of 25 Kg grapes fermented spontaneously in 30 l thermo regulated stain steel tanks, produced white wine. The indigenous yeast flora, isolated at three phases of the alcoholic fermentations, was studied. Different yeast species were isolated, purified and characterized. The restriction fragment length polymorphism of PCR-amplified fragments from the rDNA gene cluster (PCR RFLP of rDNA) has been used for the differentiation of yeast species. The standard identification procedure has been performed on representative strains that shared identical RFLP profiles showed great diversity of the yeast population. Including grape berries, must and fermented must, the following yeast species were identified: a number of Pichia and Candida species, Kloeckera apiculata, Cryptococcus curvatus, Metschnikowia pulcherrima, Kluyveromyces, as well as Saccharomyces cerevisiae and Saccharomyces stranieri. We performed microscopic, macroscopic and carbon assimilation tests by API 32C standardized system, biotechnological testing and hydrolase profiling obtained by the API-ZYM system. The most significant findings in population dynamics of yeasts in the spontaneous fermentations were bigger diversity of different species of Non- Saccharomyces in organic grapes and almost complete absence of non-Saccharomyces species, at least at grapes and at the beginning of the alcoholic fermentations at conventionally cultivated grapes, from all the examined PGI zones in all the three years of the study. The use and enhancement of indigenous yeasts is an increasing trend. Rapid identification of the yeast population is necessary for successful monitoring of the fermentation process and for obtaining a good wine quality as well as contributing to the optimization of Greek wine production.

Genome-wide identification, characterization and expression analysis of lineage-specific genes within Hanseniaspora yeasts.

Lineage-specific genes (LSGs) are defined as genes with sequences that are not significantly similar to those in any other lineage. LSGs have been proposed, and sometimes shown, to have significant effects in the evolution of biological function. In this study, two sets of Hanseniaspora spp. LSGs were identified by comparing the sequences of the Kloeckera apiculata genome and of 80 other yeast genomes. This study identified 344 Hanseniaspora-specific genes (HSGs) and 109 genes ('orphan genes') specific to K. apiculata. Three thousand three hundred thirty-oneK. apiculata genes that showed significant similarity to at least one sequence outside the Hanseniaspora were classified into evolutionarily conserved genes. We analyzed their sequence features, functional categories, gene origin, gene structure and gene expression. We also investigated the predicted cellular roles and Gene Ontology categories of the LSGs using functional inference. The patterns of the functions of LSGs do not deviate significantly from genome-wide average. The results showed that a few LSGs were formed by gene duplication, followed by rapid sequence divergence. Many of the HSGs and orphan genes exhibited altered expression in response to abiotic stress. Studying these LSGs might be helpful for understanding the molecular mechanism of yeast adaption.

The Shared and Specific Genes and a Comparative Genomics Analysis within Three Hanseniaspora Strains.

Kloeckera apiculata plays an important role in the inhibition of citrus postharvest blue and green mould diseases. This study was based on the previous genome sequencing of K. apiculata strain 34-9. After homologous comparison, scaffold 27 was defined as the mitochondrial (mt) sequence of K. apiculata 34-9. The comparison showed a high level of sequence identity between scaffold 27 and the known mtDNA of Hanseniaspora uvarum. The genome sequence of H. vineae T02/19AF showed several short and discontinuous fragments homologous to the mtDNA of H. uvarum. The shared and specific genes of K. apiculata, H. uvarum, and H. vineae were analysed by family using the TreeFam methodology. GO analysis was used to classify the shared and specific genes. Most of the gene families were classified into the functional categories of cellular component and metabolic processes. The whole-genome phylogram and genome synteny analysis showed that K. apiculata was more closely related to H. uvarum than to H. vineae. The genomic comparisons clearly displayed the locations of the homologous regions in each genome. This analysis could contribute to discovering the genomic similarities and differences within the genus Hanseniaspora. In addition, some regions were not collinearity-matched in the genome of K. apiculata compared with that of H. uvarum or H. vineae, and these sequences might have resulted from evolutionary variations.

Biocontrol efficacy of Pichia membranaefaciens and Kloeckera apiculata against Monilinia fructicola and their ability to induce phenylpropanoid pathway in plum fruit

Strains belonging to the species Pichia membranaefaciens and Kloeckera apiculata were tested as biocontrol agents (BCAs) against brown rot caused by Monilinia fructicola in plum fruit. The two yeast strains demonstrated significant antifungal activities at concentration of 5 × 108 cells/mL. Effective colonization in the wounds and high population size to compete for nutrition and space with pathogen contributed to the control mechanism of P. membranaefaciens and K. apiculata. Besides, P. membranaefaciens and K. apiculata could activate the phenylpropanoid pathway of plum to strengthen its cell wall and prevent pathogenic invasion. Both of the yeasts significantly accelerated activities of related enzymes such as phenylalanine ammonia lyase, cinnamic acid 4-hydroxylase, p-coumaroyl: CoA ligase and peroxidase. Those enzymes enhanced biosynthesis of some active metabolites of plum such as lignin, flavonoid and total phenolics.

Multifragment melting analysis of yeast species isolated from spoiled fruits.

In this study, we developed a novel approach, multifragment melting analysis (MFMA), based on the simultaneous analysis of the melting characteristics of multiple DNA fragments for the differentiation and identification of yeast species isolated from spoiled fruits. In total, 183 yeast isolates recovered from spoiled fruit samples were differentiated and grouped using MFMA. Six different DNA fragments of the 26S rRNA gene showing a high interspecific heterogeneity were amplified, and the PCR products were individually subjected to MFMA. An excellent discrimination and classification were obtained when the melting characteristics of all target DNA fragments for each species were simultaneously assessed. Species-level identification was performed by sequence analysis of representative isolatesfrom each group. In the fruit samples, Hanseniaspora uvarum (Kloeckera apiculata) was found to be the most frequently isolated species followed by members of the Pichia genus, namely P. kluyveri, P. fermentans and P. kudriavzevii (Issatchenkia orientalis). Multifragment melting analysis provided a rapid and reliable approach for discrimination and grouping of a large number of yeast isolates recovered from fruit samples prior to sequence analysis-based identification. The MFMA has great potential for fast andaccurate investigation of yeast communities associated with food spoilage to determine their sources and routes and to prevent contamination.

Glycolytic Functions Are Conserved in the Genome of the Wine Yeast Hanseniaspora uvarum, and Pyruvate Kinase Limits Its Capacity for Alcoholic Fermentation.

Hanseniaspora uvarum (anamorph Kloeckera apiculata) is a predominant yeast on wine grapes and other fruits and has a strong influence on wine quality, even when Saccharomyces cerevisiae starter cultures are employed. In this work, we sequenced and annotated approximately 93% of the H. uvarum genome. Southern and synteny analyses were employed to construct a map of the seven chromosomes present in a type strain. Comparative determinations of specific enzyme activities within the fermentative pathway in H. uvarum and S. cerevisiae indicated that the reduced capacity of the former yeast for ethanol production is caused primarily by an ∼10-fold-lower activity of the key glycolytic enzyme pyruvate kinase. The heterologous expression of the encoding gene, H. uvarumPYK1 (HuPYK1), and two genes encoding the phosphofructokinase subunits, HuPFK1 and HuPFK2, in the respective deletion mutants of S. cerevisiae confirmed their functional homology.IMPORTANCEHanseniaspora uvarum is a predominant yeast species on grapes and other fruits. It contributes significantly to the production of desired as well as unfavorable aroma compounds and thus determines the quality of the final product, especially wine. Despite this obvious importance, knowledge on its genetics is scarce. As a basis for targeted metabolic modifications, here we provide the results of a genomic sequencing approach, including the annotation of 3,010 protein-encoding genes, e.g., those encoding the entire sugar fermentation pathway, key components of stress response signaling pathways, and enzymes catalyzing the production of aroma compounds. Comparative analyses suggest that the low fermentative capacity of H. uvarum compared to that of Saccharomyces cerevisiae can be attributed to low pyruvate kinase activity. The data reported here are expected to aid in establishing H. uvarum as a non-Saccharomyces yeast in starter cultures for wine and cider fermentations.

Inhibitory effect of Pichia membranaefaciens and Kloeckera apiculata against Monilinia fructicola and their biocontrol ability of brown rot in postharvest plum

The use of antagonistic yeasts to control postharvest pathogens is a promising alternative to fungicides. The effect of the yeast antagonists Pichia membranaefaciens and Kloeckera apiculata for controlling brown rot of plums in postharvest and the antifungal activity of the two yeast strains in in vitro conditions against Monilinia fructicola were investigated. In in vivo trials, both P. membranaefaciens and K. apiculata showed a significant reduction of rot incidence produced by M. fructicola by 76.0% and 65.8%, respectively. In in vitro trials, spore germination and mycelial growth of M. fructicola were markedly inhibited by P. membranaefaciens and K. apiculata. In addition, the two antagonistic yeasts, especially K. apiculata, had attachment to the hyphae of M. fructicola. Moreover, P. membranaefaciens and K. apiculata secreted hydrolytic enzymes, such as chitinase (CHI) and β-1, 3-glucanase (GLU). According to these results, P. membranaefaciens and K. apiculata might have the ability to parasitize M. fructicola. The volatile organic compounds (VOCs) produced by P. membranaefaciens and K. apiculata had a significant inhibitory effect on M. fructicola in vitro and in vivo. VOCs in a simultaneous incubation (SI) trial showed the best inhibition.

Yeast Biodiversity in Vineyards and Wineries and Its Importance to the South African Wine Industry. A Review

The art of winemaking is as old as human civilization and the use of yeast in this complex ecological and biochemical process dates back to ancient times. Traditionally, yeasts associated with grape berries were simply allowed to ferment the sugars to ethanol, carbon dioxide and other minor, but important, metabolites. Spontaneous fermentations are still being used in boutique wineries that depend more on vintage variability. Various microbes found on the surface of grape skins and the indigenous microbiota associated with winery surfaces participate in these natural wine fermentations. Yeasts of the genera Kloeckera, Hanseniaspora and Candida predominate in the early stages, followed by several species of Metschnikowia and Pichia (including those species that were previously assigned to the genus Hansenula) in the middle stages when the ethanol rises to 3-4%. The latter stages of natural wine fermentations are invariably dominated by the alcohol-tolerant strains of Saccharomyces cerevisiae. However, other yeasts, such as species of Brettanomyces, Kluyveromyces, Schizosaccharomyces, Torulaspora and Zygosaccharomyces also may be present during the fermentation and can occur in the resultant wine. By contrast, the rule, rather than the exception, for modern wineries depending on reliable fermentation and the production of wines with predictable quality, is the use of specially selected starter cultures of Saccharomyces. However, the use of such cultures may not necessarily prevent the growth and metabolic activity of indigenous, winery associated strains of S. cerevisiae or other wild yeasts such as Kloeckera apiculata, Hanseniaspora uvarum, Candida stellata and Torulaspora delbrueckii. It is therefore clear that both spontaneous and inoculated wine fermentations are affected by the diversity of yeasts associated with the vineyard (natural habitat) and winery (man-made niche). In light of this, focused taxonomic surveys within an ecological framework are essential to preserve and exploit the hidden oenological potential of the untapped wealth of yeast biodiversity in our wine-producing regions. To achieve this, yeast taxonomists need to continue to isolate and characterize new yeast species and strains, while wine microbiologists develop improved identification techniques that differentiate more efficiently among individual strains. At the same time such biological surveys will complement strain development and the current international effort of molecular biologists to assign a biological function to the products of each of the 6000 genes identified by computer analysis of the nucleotide sequence of the 16 chromosomes of a laboratory strain of S. cerevisiae. Furthermore, only when we have a much better understanding of yeast biodeversity, biogeography, ecology and the interaction within yeast communities will we be able to optimally harness gene technology that will benefit both the wine producer and the consumer.

Genome sequencing and analysis of Kloeckera apiculata strain 34-9, a biocontrol agent against postharvest pathogens in citrus

Kloeckera apiculata, as the anamorphic state of Hanseniaspora uvarum from the Ascomycota phylum, plays an important role in the inhibition of fungal diseases in plants and spontaneous wine fermentation. This study was performed to sequence and analyze the whole genome of K. apiculata strain 34-9; This analysis provides further genomic features and assists functional research. The complete genome was determined using an Illumina HiSeq 2000 system applying paired-end and mate-pair methods to construct four reads libraries. The data assembly of all the reads resulted in a total genome size of 8.1 Mb, including 106 contigs, which were assembled into 41 scaffolds with a 31.95 % G+C content and a 234X sequence coverage. The performance of the gene prediction and functional annotation revealed that 2724 of 3786 protein-coding genes matched the KOG database, and 1127 genes were classified into GO categories. Further genome features analyses found 1066 microsatellite sites, 71 tRNAs, 3 rRNAs and 3 microRNAs in the genomic DNA. A prediction of the metabolic pathways identified potentially crucial genes for explaining the phenylalanine pathway involved in biocontrol. Comparisons with the typical yeasts Lachancea thermotolerans, Kluyveromyces lactis and Saccharomyces cerevisiae revealed the particularity and difference of K. apiculata strain 34-9. The genome alignments among Hanseniaspora vineae T02/19AF, K. apiculata DSM 2768 and 34-9 indicated numerous homologous regions distributed over the genomes between strain DSM2768 and 34-9. A SSR analysis identified that mono- and tri- nucleotide repeat types were more abundant in all six types, likely affecting the evolution of K. apiculata.

Yeast diversity in new, still fermenting wine "federweisser"

The aim of this study was to isolate and identify yeasts in different new wine "federweisser" samples. We collected the samples at the end of the August 2015 and in the middle of the September 2015. Used 15 new wine samples in this study (5 white and 10 red) were from the local Slovak winemakers. Irsai Oliver (3), Moravian Muscat (2), Agria/Turan (1), Dornfelder (3), Blue Frankish (3), Pinot Noir (1) and Saint Laurent (2). Three cultivation media were used for detection of yeasts in "federweisser" samples. Malt extract agar base (MEA), Wort agar (WA) and Wild yeast medium (WYM) were used for the cultivation of yeasts. Cultivation was performed by spread plate method. Ethanol/formic acid extraction procedure was used for preparation of samples. MALDI-TOF Mass Spectrometer (Microflex LT/SH) (Bruker Daltonics, Germany) was used for the identification of yeasts. We identified seven different strains of Saccharomyces cerevisiae (23; 70%), two strains of Kloeckera apiculata [teleomorph Hanseniaspora uvarum] (7; 21%), and one strain of Pichia kluyveri (1; 3%), Pichia occidentalis [anamorph Candida sorbosa] (1; 3%) and Metschnikowia pulcherrima (1; 3%) in 15 new wine "federweisser" samples. Saccharomyces cerevisiae was dominant species in each new wine sample, and formed creamy convex colonies with circular edge. Metschnikowia pulcherrima formed convex to pulvinate, circular white-pink colored colonies, Kloeckera apiculata formed flat, circular smooth colonies with turquoise center with gray edge, Pichia occidentalis formed irregular pulvinate light-cream colored colonies, and Pichia kluyveri formed turquoise, convex, undulate and smooth colonies on Malt extract agar base with bromocresol green.

Comparative transcriptional profiling of orange fruit in response to the biocontrol yeast Kloeckera apiculata and its active compounds.

BackgroundThe yeast Kloeckera apiculata strain 34–9 is an antagonist that shows biological control activity against the postharvest fungal pathogens of citrus. An antifungal compound, 2-phenylethanol (PEA), has been identified from the extract of K. apiculata. To better understand the molecular processes underlying the response of citrus fruit tissue to K. apiculata, the extract and PEA, microarray analyses were performed on navel oranges using an Affymetrix Citrus GeneChip.ResultsAs many as 801, 339 and 608 differentially expressed genes (DEGs) were identified after the application of K. apiculata, the extract and PEA, respectively. In general, K. apiculata induced the expression of defence-related genes. In addition to chitinase and β-1,3-glucanase, genes involved in ethylene (ET), jasmonic acid (JA), calcium signalling, MAPK signalling and phenylalanine metabolism were induced. In contrast, monodehydroascorbate reductase, superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and carotenoid biosynthesis genes were down-regulated. The expression profiles for the extract- and PEA-treated samples were similar to that found for yeast (sharing 57.4 % DEGs), with a significant increase in the transcript levels of defence-related genes.ConclusionThis study provides a global picture of the gene expression changes in navel oranges after the application of the antagonist yeast K. apiculata, its extract and PEA. The interpretation of the DEGs revealed new insight into the molecular processes that regulate the defence responses in orange tissue.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-2333-3) contains supplementary material, which is available to authorized users.