The glucosinolates of Brassicaceae plants are converted into bioactive isothiocyanates and other volatiles during a challenge by pathogens and other biotic stressors. However, the role of alternative downstream products with weaker potency (e.g., nitriles) is far from being fully understood. This study tested the possible synergistic antifungal interaction between various glucosinolate-derived nitriles and 2-phenylethyl isothiocyanate (PEITC) on 45 fungal strains, including endophytes from horseradish roots (Brassicaceae) and soil fungi, using an airtight system enabling the accurate study of extremely volatile antifungal agents. The median minimal inhibitory concentrations (MICs) were 1.28, 6.10, 27.00 and 49.72 mM for 1H-indole-3-acetonitrile (IAN), 3-phenylpropanenitrile (PPN), 4-(methylsulfanyl)-butanenitrile (MSBN) and 3-butenenitrile (BN, = allyl cyanide), respectively. Thus, nitriles were considerably weaker antifungal agents compared to PEITC with a median MIC of 0.04 mM. For the same nitriles, the median fractional inhibitory concentration indices (FICIs) of the combinations were 0.562, 0.531, 0.562 and 0.625, respectively. Altogether, 47.7%, 56.8%, 50.0% and 27.3% of tested fungal strains showed a synergistic antifungal activity (FICI ≤ 0.5) for the nitrile–isothiocyanate combinations, respectively. Hypocreales strains showed the least sensitivity towards the GSL decomposition products and their combinations. The mean MIC values for PEITC showed 0.0679 ± 0.0358, 0.0400 ± 0.0214, 0.0319 ± 0.0087 and 0.0178 ± 0.0171 mM for Hypocreales, Eurotiales, Glomerellales and Pleosporales, respectively. In addition, nitriles, especially IAN, also showed significant differences. For the same fungi, the median FICI values fell in the ranges of 0.61–0.67, 0.52–0.61, 0.40–0.50 and 0.48–0.67, respectively, depending on the nitrile. Our results suggest that glucosinolate-derived nitriles may enhance isothiocyanate antifungal activity and that they may play an active role in shaping the plant microbiome and contribute to the filtering of microbes by plants.

Fission yeasts have a unique life history and exhibit distinct evolutionary patterns from other yeasts. Besides, the species demonstrate stable genome structures despite the relatively fast evolution of their genomic sequences. To reveal what could be the reason for that, comparative genomic analyses were carried out. Our results provided evidence that the structural and sequence evolution of the fission yeasts were correlated. Moreover, we revealed ancestral locally collinear blocks (aLCBs), which could have been inherited from their last common ancestor. These aLCBs proved to be the most conserved regions of the genomes as the aLCBs contain almost eight genes/blocks on average in the same orientation and order across the species. Gene order of the aLCBs is mainly fission-yeast-specific but supports the idea of filamentous ancestors. Nevertheless, the sequences and gene structures within the aLCBs are as mutable as any sequences in other parts of the genomes. Although genes of certain Gene Ontology (GO) categories tend to cluster at the aLCBs, those GO enrichments are not related to biological functions or high co-expression rates, they are, rather, determined by the density of essential genes and Rec12 cleavage sites. These data and our simulations indicated that aLCBs might not only be remnants of ancestral gene order but are also maintained by natural selection.

Background: Mycotoxin-producing fungal species and their mycotoxins pose a global threat for crop production and for human and animal health. Given the increasing demand for healthier food and feed, alternative non-pesticide approaches for reducing fungal infections in crops and eliminating mycotoxin contamination in feedstock are becoming more prevalent. For such purposes, yeast species can be good candidates. Thus, the present study examined the mycotoxin tolerance and mycotoxin elimination ability of several yeast strains belonging to the Trichomonascaceae family. Results: While none of the tested yeasts inhibited the growth of different Fusarium species, several yeast strains exhibited tolerance to Fusarium mycotoxins such as deoxynivalenol, zearalenone, T-2 toxin, and fumonisin B1. Sugiyamaella novakii strains displayed exceptional tolerance for the tested mycotoxins. Besides, phylogenetic analyses suggested that tolerant species clustered more closely to each other than to the sensitive species. Although whole genome sequencing of S. novakii NCAIM Y.00986 revealed several enzyme-coding genes that may have a role in mycotoxin elimination, significant mycotoxin elimination was not achieved in the case of deoxynivalenol, T-2 toxin, and fumonisin B1. However, S. novakii successfully eliminated zearalenone, likely due to cell wall adsorption rather than enzymatic degradation. Conclusions: This study highlights the potential of S. novakii for zearalenone detoxification and emphasizes the role of yeast cell walls in mycotoxin mitigation strategies.

Gene targeting is a commonly used method to reveal the function of genes. Although it is an attractive tool for molecular studies, it can frequently be a challenge because its efficiency can be low and it requires the screening of a large number of transformants. Generally, these problems originate from the elevated level of ectopic integration caused by non-homologous DNA end joining (NHEJ). To eliminate this problem, NHEJ-related genes are frequently deleted or disrupted. Although these manipulations can improve gene targeting, the phenotype of the mutant strains raised the question of whether mutations have side effects. The aim of this study was to disrupt the lig4 gene in the dimorphic fission yeast, S. japonicus, and investigate the phenotypic changes of the mutant strain. The mutant cells have shown various phenotypic changes, such as increased sporulation on complete medium, decreased hyphal growth, faster chronological aging, and higher sensitivity to heat shock, UV light, and caffeine. In addition, higher flocculation capacity has been observed, especially at lower sugar concentrations. These changes were supported by transcriptional profiling. Many genes belonging to metabolic and transport processes, cell division, or signaling had altered mRNA levels compared to the control strain. Although the disruption improved the gene targeting, we assume that the lig4 inactivation can cause unexpected physiological side effects, and we have to be very careful with the manipulations of the NHEJ-related genes. To reveal the exact mechanisms behind these changes, further investigations are required.

To learn about the yeast biodiversity of Hungarian honeys and to isolate osmotolerant yeasts, fifteen different honey varieties, beeswax, and bee bread were purchased, and samples of another, but highly osmotic material, tree sap (cherry, sour cherry, and plum), were collected from the northeastern region of the country. In total, 60 yeast strains were isolated and their taxonomic positions were determined by barcode sequences using ITS1-NL4 primers. The honey products contained mostly Zygosaccharomyces and Starmerella species. In addition, Hanseniaspora uvarum, Rhodotorula mucilaginosa and diobovata, Sporobolomyces roseus, Filobasidium magnum, Naganishia sp., and Aureobasidium pullulans were also present in smaller numbers. In contrast, tree saps contained Metschnikowia and Pichia fermentas cells. Further results suggest that some of the yeasts in honey can only “survive”, while others can propagate at high sugar levels, generally between 600 and 700 mg/g, with a predominance of fructose. Properties important for pathogenicity, such as invasive hyphae production, gelatin melting ability, and growth at 37 °C, were also examined. Hanseniaspora uvarum and Pichia fermentans representatives seemed to be negative for gelatin hydrolysis, while the other strains were able to melt gelatin. Although some of the strains could produce hyphae-like structures at 25 °C, none of them could grow at 37 °C.

Tokaj botrytized sweet wines are traditionally aged for several years in wood barrels or bottles. As they have significant residual sugar content, they are exposed to microbial contamination during ageing. Osmotolerant wine-spoilage yeasts are most commonly found in the Tokaj wine-growing region in the species Starmerella spp. and Zygosaccharomyces spp. For the first time, Z. lentus yeasts were isolated from post-fermented botrytized wines. Our physiological studies confirmed that these yeast strains are osmotolerant, with high sulphur tolerance and 8% v/v alcohol tolerance, and that they grow well at cellar temperature in acidic conditions. Low β-glucosidase and sulphite reductase activities were observed, whereas protease, cellulase, and α-arabinofuranosidase extracellular enzyme activities were not detected. Molecular biology analyses carried out by RFLP analysis of mtDNA revealed no remarkable differences between strains, while microsatellite-primed-PCR fingerprinting of the (GTG)₅ microsatellite and examination of chromosomal pattern revealed considerable diversity. The fermentative vigour of the tested Z. lentus strains was found to be significantly lower compared to the control Saccharomyces cerevisiae (Lalvin EC1118). It can be concluded that Z. lentus is a potential spoilage yeast in oenology which may be responsible for the initiation of secondary fermentation of wines during ageing.