Antagonistic Yeast Research Articles

Transcriptome analysis reveals mechanisms of the disease resistance in postharvest kiwifruit induced by Meyerozyma caribbica

Meyerozyma caribbica, an antagonistic yeast, effectively controls the postharvest blue mold decay of kiwifruit. Our previous study explored the mechanism of M. caribbica inhibiting the postharvest blue mold in kiwifruit at the physiological level, but its molecular mechanism is still unknown. This study investigated the related molecular mechanisms of disease-resistance in kiwifruits induced by M. caribbica based on transcriptome analysis. In addition, the effects of M. caribbica on the natural decay and storage quality of postharvest kiwifruit were investigated. The research showed that M. caribbica could reduce natural decay during kiwifruit storage without an apparent adverse effect on quality. The transcriptome analysis of postharvest kiwifruit found that there were 2916 DEGs, of which 1986 were up-regulated and 930 were down-regulated. KEGG pathway analysis showed that the plant-pathogen interaction pathway, glycolysis/gluconeogenesis pathway, flavonoid biosynthesis pathway, glutathione metabolism pathway and phenylpropane biosynthesis pathway were associated with the enhancement of kiwifruit resistance. The analysis of related metabolic pathways and functional analysis of related DEGs showed that M. caribbica could improve the expression of genes related to kiwifruit resistance, which are associated with induction of fruit resistance, mediated substance transport, improvement of cell wall strength, enhancement of plant antioxidant capacity, signal transduction and secondary metabolite synthesis, etc. These results provide a reference for future research on the use of antagonistic yeasts to prevent and control postharvest diseases of fruits and vegetables, and provide a theoretical basis for the practical application of antagonistic yeasts.

Multiple pathways involved in the Ca ascorbate-induced enhancement of Meyerozyma guilliermondii biocontrol efficacy

The external environment and yeast’s inherent physiological characteristics play important roles in the biocontrol efficacy of antagonistic yeast. Attention has been focused on increasing biocontrol efficacy by improving yeast environmental adaptability in recent years. In this study, the effect and mechanism of calcium ascorbate (Ca ascorbate) on enhancement of Meyerozyma guilliermondii biocontrol effectiveness were investigated based on transcriptome sequencing, and physiological and biochemical activity analysis of yeast cells. The results demonstrated that the yeast induced by 0.2 g/L Ca ascorbate inhibit gray decay substantially compared with the control, non-induced, ascorbic acid (VC) and calcium chloride (CaCl2) induced groups.The results of transcriptome sequencing showed that the differentially expressed genes (DEGs) of M. guilliermondii induced by Ca ascorbate were mainly enriched in those GO functions such as “cell process, metabolic process, antioxidant” and KEGG pathways such as “ribosome, metabolism, cell cycle”. Ca ascorbate induction could significantly upregulate the expression of genes related to ribosome synthesis (RIM101, PAN3, NHP2, and RPS19A), growth and metabolism (HXT2 and SDH4), and antioxidation (FMN1 and SNZ1). The accelerated growth dynamics and cell metabolic activity as well as the elevated antioxidant enzyme activity were all in line with the transcriptomic data. As expected, the increased antioxidant enzyme activity reduced the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA). These results demonstrated that the mechanism of Ca ascorbate-induced enhancement of biocontrol efficacy is related to accelerating yeast proliferation and colonization, improving nutrient utilization, enhancing cell homeostasis and cell wall structure, and improving the environmental adaptability of yeast cells. Additionally, Ca2+ also has a synergistic effect on yeast physiological activity and antioxidant activity to promote the improvement of yeast biocontrol efficacy.

Overexpression of the SDR gene improves the ability of Meyerozyma guilliermondii to degrade patulin in pears and juices.

The intracellular enzymes of antagonistic yeast are effective in controlling patulin (PAT) contamination. However, countless enzymes that have been revealed remain functionally uncharacterized. The study built on previous transcriptomic data obtained by our research group to amplify and express a gene encoding a short-chain dehydrogenase/reductase (SDR) in Meyerozyma guilliermondii. Overexpression of SDR increased the tolerance of M. guilliermondii to PAT and the ability to degrade PAT of the intracellular enzymes. Furthermore, MgSDR-overexpressed M. guilliermondii showed higher PAT degradation in juices (apple and peach) and controlled the blue mold of pears at 20°C and 4°C while significantly reduced the content of PAT and the biomass of Penicillium expansum in decayed tissues than wild-type M. guilliermondii. This study provides theoretical references for the subsequent heterologous expression, formulation, and application of the SDR protein from M. guilliermondii and contributes to elucidating the PAT degradation mechanism of antagonistic yeasts.

Proteomic analysis reveals the mechanisms of improved biocontrol efficacy of Sporidiobolus pararoseus Y16 induced by γ-aminobutyric acid

Sporidiobolus pararoseus Y16 is a potential antagonistic yeast against various plant fungal pathogens, especially table grapes, and its biocontrol efficacy could be induced significantly by γ-aminobutyric acid (GABA). Our previous studies explored the physiological mechanisms of induced biocontrol efficacy of the yeast by GABA, but the molecular mechanisms are still unknown. This study aimed to study the effects of GABA-induced culture of S. pararoseus Y16 on natural decay and different quality parameters of table grapes; to analyze the proteomic changes of GABA-induced S. pararoseus Y16. Our results indicated that GABA-induced S. pararoseus Y16 significantly reduced the natural decay rate of postharvest grapes but retained the quality parameters, such as weight loss percentage, firmness, soluble solids, titratable acid, soluble protein and vitamin C, compared to the control group. Proteomic technology could comprehensively explain the molecular mechanism of improved biocontrol efficacy of S. pararoseus Y16 by GABA induction. The proteomic analysis of GABA-treated S. pararoseus Y16 found that there were 326 DEPs, of which 160 were up-regulated and 166 were down-regulated. KEGG pathway analysis showed that the synthesis and metabolism of deoxynucleotides pathway, citric acid cycle and related metabolism pathway, GABA shunting and lysine synthesis pathway, synthesis of terpenoids pathway and zymosterol biosynthesis pathway were associated with the enhancement of yeast biocontrol efficacy. The analysis of related metabolic pathways and other DEPs showed that GABA-treated S. pararoseus Y16 enhanced the ability of growth, reproduction, metabolism, stress resistance and amino acid synthesis of S. pararoseus Y16, thereby improving the biocontrol efficacy of the yeast. These findings can provide new ideas and methods for enhancing the biocontrol efficacy of antagonistic yeast, thus promoting the commercial application of antagonistic yeast.

Screening bisphenols in complex samples via a planar Arxula adeninivorans bioluminescence bioassay

The Arxula yeast bisphenol screen (A-YBS) utilizes the bioluminescent Arxula adeninivorans yeast–based reporter cells for tailored analysis of bisphenols, one of the major endocrine-disrupting compound groups. For the first time, this bioreporter has been applied on the high-performance thin-layer chromatography (HPTLC) adsorbent surface to develop a respective planar bioluminescence bioassay (pA-YBS). The goal was to combine the advantages of HPTLC with a more selective bioassay detection for bisphenols. The performance of this pA-YBS bioluminescence bioassay was demonstrated by calculating the half-maximal effective concentration (EC50) of bisphenols compared to references. The EC50 ranged from 267 pg/band for bisphenol Z and 322 pg/band for bisphenol A (BPA) to > 1 ng/band for other bisphenols (BPC, BPE, BPF, and BPS) and references (17β-estradiol and 17α-ethinylestradiol). The EC50 value of BPA was three times more sensitive in signal detection than that of 17β-estradiol. The visual or videodensitometric limit of detection of BPA was about 200 pg/zone. The higher signal intensity and sensitivity for BPA confirmed the tailored bioassay selectivity compared to the existing estrogen screen bioassay. It worked on different types of HPTLC silica gel plates. This HPTLC–UV/Vis/FLD–pA-YBS bioluminescence bioassay method was used to analyze complex mixtures such as six tin can migrates, five thermal papers, and eleven botanicals. The detected estrogenic compound zones in the tin can migrates were successfully verified via the duplex planar yeast antagonist estrogen screen (pYAES) bioassay. The two bisphenols A and S were identified in one out of five thermal papers and confirmed with high-resolution mass spectrometry. No bisphenols were detected in the botanicals investigated via the pA-YBS bioluminescence bioassay. However, the botanicals proved to contain phytoestrogens as detected via the pYAES bioassay, which confirmed the tailored bioassay selectivity. This HPTLC–UV/Vis/FLD–pA-YBS bioluminescence bioassay is suited for cost-efficient analysis of BPA in complex samples, with no need for sterile conditions due to the fast workflow.

TMT-Based Proteomic Analysis of Hannaella sinensis-Induced Apple Resistance-Related Proteins.

Studies on the molecular mechanism of antagonistic yeasts to control apple postharvest diseases are not comprehensive enough. Our preliminary investigations screened the biocontrol effect of Hannaella sinensis, an antagonistic yeast, and discovered its control efficacy on apple blue mold decay. However, the molecular mechanism of H. sinensis-induced resistance in apple has not been studied. In this study, proteins from apple treated with H. sinensis and sterile saline were analyzed using TMT proteomics technology. It was found that H. sinensis treatment induced the expressions of apple resistance-related proteins. Among the proteins in H. sinensis-induced apple, proteins related to plant defense mechanisms, such as reactive oxygen species scavenging, improvement of plant resistance and synthesis of resistant substances, improvement of plant disease resistance, the degradation of the pathogen cell wall, cell signaling, antibacterial activity, transport of defense-related substances, and protein processing, were differentially regulated. The results of this study revealed the underlying molecular mechanisms of H. sinensis-induced apple resistance at the protein level; the results also provided a theoretical basis for the commercial application of H. sinensis.

Pantothenate Auxotrophy in a Naturally Occurring Biocontrol Yeast.

The genus Hanseniaspora is characterized by some of the smallest genomes among budding yeasts. These fungi are primarily found on plant surfaces and in fermented products and represent promising biocontrol agents against notorious fungal plant pathogens. In this work, we identify pantothenate auxotrophy of a Hanseniaspora meyeri isolate that shows strong antagonism against the plant pathogen Fusarium oxysporum. Furthermore, strong biocontrol activity in vitro required both pantothenate and biotin in the growth medium. We show that the H. meyeri isolate APC 12.1 can obtain the vitamin from plants and other fungi. The underlying reason for the auxotrophy is the lack of two key pantothenate biosynthesis genes, but six genes encoding putative pantothenate transporters are present in the genome. By constructing and using a Saccharomyces cerevisiae reporter strain, we identified one Hanseniaspora transporter that conferred pantothenate uptake activity to S. cerevisiae. Pantothenate auxotrophy is rare and has been described in only a few bacteria and in S. cerevisiae strains that were isolated from sake. Such auxotrophic strains may seem an unexpected and unlikely choice as potential biocontrol agents, but they may be particularly competitive in their ecological niche and their specific growth requirements are an inherent biocontainment strategy preventing uncontrolled growth in the environment. Auxotrophic strains, such as the H. meyeri isolate APC 12.1, may thus represent a promising strategy for developing biocontrol agents that will be easier to register than prototrophic strains, which are normally used for such applications. IMPORTANCE As a precursor of the essential coenzyme A (CoA), pantothenate is present in all organisms. Plants, bacteria, and fungi are known to synthesize this vitamin, while animals must obtain it through their diet. Pantothenate auxotrophy has not been described in naturally occurring, environmental fungi and is an unexpected property for an antagonistic yeast. Here, we report that yeasts from the genus Hanseniaspora lack key enzymes for pantothenate biosynthesis and identify a transporter responsible for the acquisition of pantothenate from the environment. Hanseniaspora isolates are strong antagonists of fungal plant pathogens. Their pantothenate auxotrophy is a natural biocontainment feature that could make such isolates interesting candidates for new biocontrol approaches and allow easier registration as plant protection agents than prototrophic strains.

Genome-wide discovery of Pichia galeiformis-secreted proteins and their induction of green mold resistance in citrus fruit

Microbe-secreted proteins could alter plant defense systems, but yeast-secreted proteins and their impact on plant disease resistance remains uninvestigated. As our team had previously found that Pichia galeiformis (P. galeiformis) induced citrus green mold resistance, the purpose of this study was to identify its secreted proteins and their role in disease resistance. The genome of P. galeiformis was completely sequenced, and 4386 putative protein-coding genes were identified. The crude culture of P. galeiformis contained 1443 proteins. Among these proteins, 55 were identified as secreted proteins with an N-terminal signal peptide and lacking transmembrane structural domain. Overexpression of secreted proteins 2-gene0581, 22-gene0896, 23-gene0290, 12-gene3564, 9-gene0639, and 15-gene0649 significantly reduced citrus fruit disease incidence and lesion diameter. And the best effect was achieved by 15-gene0649 treatment. Notably, P. galeiformis 15-gene0649, which was named PgSCP, encoded a novel protein. The purified protein PgSCP demonstrated considerable ability to prevent green mold caused by Penicillium digitatum in citrus. This study presented here confirms that yeast could increase citrus green mold resistance through secreted proteins. Those secreted proteins offer a fresh insight for controlling postharvest disease in citrus fruit as well as a new commercialization and application method for antagonistic yeast.

Recent Insights into the Use of Antagonistic Yeasts for Sustainable Biomanagement of Postharvest Pathogenic and Mycotoxigenic Fungi in Fruits with Their Prevention Strategies against Mycotoxins.

Fungi-induced postharvest diseases are the leading causes of food loss and waste. In this context, fruit decay can be directly attributed to phytopathogenic and/or mycotoxin-producing fungi. The U.N. Sustainable Development Goals aim to end hunger by 2030 by improving food security, sustainable agriculture, and food production systems. Antagonistic yeasts are one of the methods presented to achieve these goals. Unlike physical and chemical methods, harnessing antagonistic yeasts as a biological method controls the decay caused by fungi and adsorbs and/or degrades mycotoxins sustainably. Therefore, antagonistic yeasts and their antifungal mechanisms have gained importance. Additionally, mycotoxins' biodetoxification is carried out due to the occurrence of mycotoxin-producing fungal species in fruits. Combinations with processes and agents have been investigated to increase antagonistic yeasts' efficiency. Therefore, this review provides a comprehensive summary of studies on preventing phytopathogenic and mycotoxigenic fungi and their mycotoxins in fruits, as well as biocontrolling and biodetoxification mechanisms.

Biocontrol Potential of Antagonistic Yeasts on In Vitro and In Vivo Aspergillus Growth and Its AFB1 Production.

Aspergillus flavus is a major aflatoxin B1, posing significant health concerns to humans, crops, and producer fungi. Due to the undesirable consequences of the usage of synthetic fungicides, biological control using yeasts has gained more attention. In this study, eight isolates of epiphytic yeasts belonging to Moesziomyces sp., Meyerozyma sp. and Metschnikowia sp., which have been identified as antagonists, were isolated from different plants, including grapes, blueberries, hawthorns, hoşkıran, beans and grape leaf. While volatile organic compounds (VOCs) produced by Moesziomyces bullatus DN-FY, Metschnikowia aff. pulcherrima DN-MP and Metschnikowia aff. pulcherrima 32-AMM reduced in vitro A. flavus mycelial growth and sporulation, only VOCs produced by Metschnikowia aff. fructicola 1-UDM were found to be effective at reducing in vitro AFB1 production. All yeasts reduced the mycelial growth of A. flavus by 76-91%, while AFB1 production reduced to 1.26-10.15 ng/g and the control plates' growth was 1773 ng/g. The most effective yeast, Metschnikowia aff. Pulcherrima DN-HS, reduced Aspergillus flavus growth and aflatoxin B1 production on hazelnuts. The AFB1 content on hazelnuts reduced to 333.01 ng/g from 536.74 ng/g. To our knowledge, this is the first report of yeasts isolated from plants being tested as potential biological control agents to reduce AFB1 production on hazelnuts.

Biocontrol efficacy of Wickerhamomyces anomalus on tomato field diseases and study of the relevant mechanisms via microbiome analysis

Tomatoes (Solanum lycopersicum L.) are vulnerable to infections by pathogens found in a complex environment. Most of these infections are triggered by an imbalance between plant microorganisms and pathogens, leading to various tomato rots and high economic losses. This study aims to test the biocontrol ability of an antagonistic yeast, Wickerhamomyces anomalus, towards gray mold disease in tomatoes in the field and explore the relevant mechanisms through microbiome analysis of the microbial community on the surface of tomatoes. The results showed that W. anomalus decreased the tomato disease severity index during plant growth period, along with some changes in the microorganism community composition, including the increase of the abundance of some plant growth promotion bacteria such as Pantoea sp. and Pseudomonas sp. and biocontrol agents such as Golubevia sp. and Papiliotrema sp., and abundance decrease in some potential pathogens such as species of Alternaria. All these results suggest that W. anomalus could control tomato diseases in the field and the regulation in microorganism composition might be a possible mechanism.

Antimicrobial function of yeast against pathogenic and spoilage microorganisms via either antagonism or encapsulation: A review.

Contaminations of pathogenic and spoilage microbes on foods are threatening food safety and quality, highlighting the importance of developing antimicrobial agents. According to different working mechanisms, the antimicrobial activities of yeast-based agents were summarized from two aspects: antagonism and encapsulation. Antagonistic yeasts are usually applied as biocontrol agents for the preservation of fruits and vegetables via inactivating spoilage microbes, usually phytopathogens. This review systematically summarized various species of antagonistic yeasts, potential combinations to improve the antimicrobial efficiency, and the antagonistic mechanisms. The wide applications of the antagonistic yeasts are significantly limited by undesirable antimicrobial efficiency, poor environmental resistance, and a narrow antimicrobial spectrum. Another strategy for achieving effective antimicrobial activity is to encapsulate various chemical antimicrobial agents into a yeast-based carrier that has been previously inactivated. This is accomplished by immersing the dead yeast cells with porous structure in an antimicrobial suspension and applying high vacuum pressure to allow the agents to diffuse inside the yeast cells. Typical antimicrobial agents encapsulated in the yeast carriers have been reviewed, including chlorine-based biocides, antimicrobial essential oils, and photosensitizers. Benefiting from the existence of the inactive yeast carrier, the antimicrobial efficiencies and functional durability of the encapsulated antimicrobial agents, such as chlorine-based agents, essential oils, and photosensitizers, are significantly improved compared with the unencapsulated ones.

PpMYB44 positively affects salicylic acid biosynthesis in Pichia guilliermondii-induced peach fruit resistance against Rhizopus stolonifer

Antagonistic yeast induces postharvest disease resistance and delays fruit decay. Salicylic acid (SA), a signal molecule, is required for activating induced disease resistance in various harvested fruit. However, there is limited information about the transcriptional regulatory mechanism of SA biosynthesis in response to Rhizopus stolonifer in peaches. Our results showed that Pichia guilliermondii application promoted SA accumulation accompanied by increasing SA biosynthetic enzyme activity of PAL and ICS and upregulating transcripts of SA synthesis-related genes and defense genes, including PpPAL1, PpPAL2, PpICS1, PpICS2, PpCM1, PpCM2, PpCM3, PpBA2H, PpSARD1, PpCBP60g, PpPR1, PpPR2, and PpPR5. In addition, an R2R3 MYB transcription factor, PpMYB44, was induced in P. guilliermondii-peach fruit in response to fungal disease, and PpMYB44 was identified to mediate SA synthesis by binding to the promoters of PpPAL1 and PpSARD1. Furthermore, the transient overexpression of PpMYB44 in peach fruit reduced disease incidence and severity, upregulated the expression of SA synthesis-related genes (PpPAL1 and PpSARD1) and enhanced SA accumulation. Silencing of PpMYB44 in peach fruit increased disease incidence and severity, downregulated the transcript levels of PpPAL1 and PpSARD1, and decreased SA accumulation. Thus, the study indicates that PpMYB44 regulates yeast-induced disease resistance by increasing the SA content in peaches.

Effects of H.uvarum combined with KGM on postharvest diseases of blueberry

The aim of this work was to evaluate the efficacy of an innovative edible coating that combines Hanseniaspora uvarum and konjac glucomannan to preserve blueberries. The antagonistic yeast and four main fungi (Aspergillus niger, Penicillium, Alternaria alterniformis, Pseudomonas spp.) isolated from blueberry pathogens were subjected to in vitro antibacterial experiments, and the optimal concentration of antagonistic yeast was determined as 1 × 108 CFU/mL. The antibacterial mechanism of yeast against pathogenic fungi was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, viscometry, measurement of electrospray droplet size and coating thickness. Finally, the resulting spray was used to treat blueberry wound rot and to store blueberries. After 14 days of storage, the konjac glucomannan/Hanseniaspora uvarum composite coating solution was found to be more effective in maintaining blueberry quality compared with the control and konjac glucomannan groups.

Molecular Response of Meyerozyma guilliermondii to Patulin: Transcriptomic-Based Analysis

Patulin (PAT), mainly produced by Penicillium expansum, is a potential threat to health. In recent years, PAT removal using antagonistic yeasts has become a hot research topic. Meyerozyma guilliermondii, isolated by our group, produced antagonistic effects against the postharvest diseases of pears and could degrade PAT in vivo or in vitro. However, the molecular responses of M. guilliermondii over PAT exposure and its detoxification enzymes are not apparent. In this study, transcriptomics is used to unveil the molecular responses of M. guilliermondii on PAT exposure and the enzymes involved in PAT degradation. The functional enrichment of differentially expressed genes indicated that the molecular response mainly includes the up-regulated expression of genes related to resistance and drug-resistance, intracellular transport, growth and reproduction, transcription, DNA damage repair, antioxidant stress to avoid cell damage, and PAT detoxification genes such as short-chain dehydrogenase/reductases. This study elucidates the possible molecular responses and PAT detoxification mechanism of M. guilliermondii, which could be helpful to further accelerate the commercial application of antagonistic yeast toward mycotoxin decontamination.

Transcriptomic analyses reveal robust changes in the defense response of apples induced by Hannaella sinensis

Research on yeast antagonists has recently demonstrated their safety and efficacy in effectively preventing apple postharvest infections. Our previous study has revealed that the antagonistic yeast Hannaella sinensis has shown control activity against blue mold decay in apples caused by Penicillium expansum. However, the molecular networks underlying H. sinensis-treated apple's disease control mechanisms are not explored. Hence, we aimed to uncover the molecular changes of apples treated with H. sinensis based on transcriptomic analysis. Differentially expressed genes of apples treated with H. sinensis were identified through RNA-seq (152 up-regulated and 1480 down-regulated DEGs) and bioinformatic analysis. Among the DEGs, significant numbers were annotated into apple defense-related pathways, such as plant-pathogen interaction, plant hormone signal transduction, phenylpropanoid biosynthesis, tyrosine metabolism, glycerolipid metabolism, and alpha-linoleic acid pathways related to resistance regulation. Our results indicated that H. sinensis could induce disease resistance in apples, which leads to increased protection against postharvest pathogens. The current study paves the way for further understanding the biocontrol mechanism of antagonistic yeast against postharvest infections by enhancing host defense.

A method for reducing the concentrations of Fusarium graminearum trichothecenes in durum wheat grain with the use of Debaryomyces hansenii

Fusarium head blight (FHB), caused mainly by Fusarium graminearum, is one of the most dangerous diseases of durum wheat. This hemibiotrophic pathogen transitions from the biotrophic phase, during which it penetrates host tissues and secretes trichothecenes, to the necrotrophic phase which leads to the destruction of host tissues. Yeasts applied to spikes often reduce mycotoxin concentrations, but the underlying mechanisms have not been fully elucidated. Therefore, the aim of this study was to analyze the concentrations trichothecenes in durum wheat grain and changes in the F. graminearum transcriptome under the influence the Debaryomyces hansenii antagonistic yeast strain. Debaryomyces hansenii cells adhered to and formed cell aggregates/biofilm on the surface of spikes and pathogenic hyphae. Biological control suppressed the spread of F. graminearum by 90 % and decreased the content of deoxynivalenol (DON) in spikes by 31.2 %. Yeasts significantly reduced the expression of pathogen's genes encoding the rpaI subunit of RNA polymerase I and the activator of Hsp90 ATPase, but they had no effect on mRNA transcript levels of genes encoding the enzymes involved in the biosynthesis of trichothecenes. The yeast treatment reduced the number of F. graminearum operational taxonomic units (OTUs) nearly five-fold and increased the number of D. hansenii OTUs more than six-fold in the spike mycobiome. The mechanisms that suppress infections should be explored to develop effective biological methods for reducing the concentrations mycotoxins in wheat grain.

Control of postharvest blue and gray mold in kiwifruit by Wickerhamomyces anomalus and its mechanism of antifungal activity

The primary postharvest diseases of kiwifruit are blue and gray mold which are caused by Penicillium expansum and Botrytis cinerea, respectively, and result in serious economic losses. Biological control has been shown to be an effective approach for the management of postharvest diseases. Previous studies reported that the antagonistic yeast, Wickerhamomyces anomalus, exhibited strong biocontrol activity against postharvest diseases of kiwifruit. Investigating the mechanisms responsible for its biocontrol activity will provide a theoretical basis for improving the biocontrol efficiency and application of this yeast antagonist. Results of this study indicated that the antifungal properties of W. anomalus are due to the combined effect of several mechanisms. These include the inhibition of growth of fungal pathogens on PDA or PDB, rapid colonization of the surface and wounds of kiwifruit, attachment to the surface of fungal mycelia, strong ability to form a biofilm, and produce volatile organic compounds (VOCs) with antifungal activity. The VOCs produced in YPD medium exhibited more inhibitory effects than VOCs produced in NYDA medium. A total of 12 VOCs were identified. The main VOCs produced were 2-phenethyl acetate and 1-butanol, 3-methyl-. Individually, these VOCs each exhibited a excellent level of antifungal activity.

Biological Control of Brassicales Ring Spot Disease Caused by Alternaria brassicicola Using Antagonistic Yeasts

T his research investigated the biological control of Ring Spot Disease of Brassicales caused by Alternaria brassicicola, which is an agriculturally important pathogen, using antagonistic yeasts. One hundred fifteen yeasts were isolated from 38 fruits and vegetable leaves. A total of twenty-nine yeast isolates showed the inhibitory activity of A. brassicicola more than a value of 50% by the dual culture method. The result showed that three antagonistic yeast isolates Y107, Y123, and Y16 showed high inhibitory percentages at 75.00%, 73.52%, and 70.33%, respectively. Interestingly, these yeasts inhibited spore germination of A. brassicicola after 12 h within the range of 80.90 to 90.26%. Subsequently, the efficacy of the selected antagonistic yeast against Ring Spots Disease on cabbage seedlings (Brassica oleracea L. var. capitata) and Pak choi (Brassica chinensis L. var. chinensis) was tested in the greenhouse. The result indicated that antagonistic yeast isolate Y107 inhibited the disease at 72.75% and 71.42% in Cabbage seedlings and Pak choi, respectively. However, the efficacy of isolates Y123 and Y16 were not significant in disease inhibition in both Cabbage seedlings (66.67% and 66.08%) and Pak choi (69.83% and 68.92%). Additionally, the antagonistic yeast isolates were identified by phylogenetic analysis of the D1/D2 domain of the large subunit ribosomal RNA (LSU) gene. Yeast isolates Y16 and Y123 were identified to Kurtzmaniella quercitrusa, while isolate Y107 was Hanseniaspora thailandica.

Improvement of shelf-life of cherry (Prunus avium L.) by combined application of modified-atmosphere packaging and antagonistic yeast for long-distance export.

The last decade has seen a growing interest in reducing the use of chemical fungicides for postharvest decay control. In the research for new, safe alternatives, the combined application of biocontrol agents and passive modified-atmosphere packaging (MAP) has been shown to be a promising strategy to extend fruit quality. Therefore, the aim of this work was to evaluate the effect of the combined application of MAP and two antagonistic yeasts, Metschnikowia pulcherrima L672 and Pichia kudriavzevii PK18, on sweet cherry shelf life. Microbiological, physico-chemical, and quality fruit analysis from batches treated with antagonistic yeast were compared with a control batch without yeast application and a batch to which fludioxonil (Scholar®) was applied. The composition of the atmosphere and physico-chemical traits showed similar values among the different batches during cold storage. However, interestingly, the combination of MAP with the antagonistic yeasts M.pulcherrima L672 and P.kudriavzevii PK18 increases the control of microbiological spoilage with results comparable to the application of fludioxonil. In addition, these batches experienced a slight decrease in volatile compounds associated with fresh fruit aroma, whereas in the control batch an increase of altered fruit aromas was observed. The same effect of control of spoilage was observed during the shelf life period. These results showed the positive effect of the combination of antagonistic yeasts and MAP, obtaining similar results in terms of control of microbiological spoilage and physico-chemical quality compared with the application of fludioxonil. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.