Search Results (117)

Calcareous soils, characterized by high pH and calcium carbonate content, often limit the availability of essential nutrients for crops such as rice (Oryza sativa L.), reducing yield and nutritional quality. In this study, we evaluated the effect of the halotolerant yeast Debaryomyces hansenii on the growth, nutrient uptake, and phosphorus acquisition mechanisms of rice plants cultivated in calcareous soil under controlled greenhouse conditions. Plants inoculated with D. hansenii, particularly via root immersion, exhibited significantly higher SPAD chlorophyll index, plant height, and grain yield compared to controls. A modest increase (~4%) in dry matter content was also observed under sterilized soil conditions. Foliar concentrations of Fe, Zn, and Mn significantly increased in plants inoculated with D. hansenii via root immersion in non-sterilized calcareous soil, indicating improved micronutrient acquisition under these specific conditions. Although leaf phosphorus levels were not significantly increased, D. hansenii stimulated acid phosphatase activity, as visually observed through BCIP staining, and upregulated genes involved in phosphorus acquisition under both P-sufficient and P-deficient conditions. At the molecular level, D. hansenii upregulated the expression of acid phosphatase genes (OsPAP3, OsPAP9) and a phosphate transporter gene (OsPTH1;6), confirming its influence on P-related physiological responses. These findings demonstrate that D. hansenii functions as a plant growth-promoting yeast (PGPY) and may serve as a promising biofertilizer for improving rice productivity and nutrient efficiency in calcareous soils, contributing to sustainable agricultural practices in calcareous soils and other nutrient-limiting environments. Full article

Sixteen long-ripened, high-quality Cabrales cheeses from independent producers underwent a comprehensive biochemical and microbiological characterisation. Significant variations in total microbial counts and specific microbial groups were observed among the cheeses. A metataxonomic analysis identified 249 prokaryotic amplicon sequence variants (ASVs) and 99 eukaryotic ASVs, respectively, which were classified into 52 prokaryotic and 43 eukaryotic species. The predominant species included bacteria of the genera Tetragenococcus, Lactococcus (of which Lactococcus lactis was used as a starter), and Staphylococcus, followed by Brevibacterium and Corynebacterium species. The starter mould Penicillium roqueforti was highly abundant in all cheeses; Debaryomyces hansenii, Geotrichum candidum, and Kluyveromyces spp. constituted the subdominant fungal populations. Glutamic acid (≈20 mg g⁻¹) was the most abundant free amino acid in all samples, followed by lysine, leucine, and valine (≈10–13 mg g⁻¹). Moderate-to-high amounts of the biogenic amines tyramine and ornithine were detected. A large variation between cheeses of the main organic acids (lactic, acetic, or butyric) was detected. Differences between samples were also observed for the majority volatile compounds, which included organic acids, alcohols, esters, and ketones. Positive and negative correlations between bacterial and fungal species were detected, as well as between microbial populations and key biochemical markers. Among the latter, Tetragenococcus halophilus correlated positively with ethyl caprylate and hexanoic acid, and Loigolactobacillus rennini correlated positively with γ-aminobutyric acid. Conversely, Staphylococcus equorum showed a strong negative correlation with ethyl caprylate and capric acid. These microbial and biochemical insights enabled us to propose a microbiota-based starter culture comprising prokaryotic and eukaryotic components to enhance Cabrales cheese quality. Full article

The metabolic activity of fermentative microorganisms plays a critical role in determining the flavor profile of fermented meat products. Modulating carbon and nitrogen sources represents a promising strategy for enhancing product quality. In this study, Debaryomyces hansenii strains isolated from dry-cured ham were assessed in a sterile sausage model to evaluate the effects of different carbon sources (sucrose, corn starch) and nitrogen sources (leucine, soy protein isolate) on colony growth, enzyme activity, and physicochemical properties. These nutritional factors significantly affected the fermentation performance of D. hansenii. Corn starch and soy protein isolate increased colony count by 14.94% and 90%, respectively, and enhanced protease activity by 2-fold and 4.5-fold. Both treatments maintained high lipase activity (>50 U/g). Both supplements improved the water-holding capacity and decreased the water activity. Carbon sources reduced the medium pH, whereas nitrogen sources contributed to the maintenance of pH stability. A further analysis indicated that corn starch promoted the accumulation of aldehydes and ketones, which intensified the sourness and suppressed the saltiness. In contrast, soy protein isolate increased the abundance of free amino acids associated with umami and sweetness, and stimulated the formation of esters, ketones, and pyrazines, thereby enhancing flavor richness and umami intensity. Both ingredients also reduced saturated fatty acid levels and increased the unsaturated to saturated fatty acid ratio. Soy protein isolate exhibited a more pronounced effect on D. hansenii fermentation. This study provides a technical reference for enhancing the flavor characteristics of fermented meat products via the adjustment of carbon and nitrogen sources to regulate D. hansenii fermentation. Full article

Autochthonous microorganisms play critical roles in shaping the quality of Chinese sausages and may be influenced by local climate and/or processing conditions. The present study aimed to reveal the interprovincial differences in microbial community between Sichuan and Guizhou sausages, as well as driving factors based on high-throughput sequencing and bioinformatic analysis. The results indicated that Cobetia, Debaryomycetaceae, Kurtzmaniella, and Candida zeylanoides served as biomarkers for Sichuan sausages. In contrast, Enterococcus, unclassified Cyanobacteriales, Lactobacillales, Aspergillus vitricola, Mortierella, Fusarium, and Penicillium were identified as biomarkers for Guizhou sausages. Furthermore, salt content and moisture level showed positive correlations with Cobetia, Staphylococcus, Debaryomyces, and Kurtzmaniella, mainly found in Sichuan sausages. Conversely, pH and water activity (Aw) were positively associated with potential pathogenic bacteria (e.g., Vibrio, Cyanobacteria, Enterococcus, and Aeromonas) and fungi (e.g., Aspergillus, Fusarium, and Penicillium), which were mainly distributed in Guizhou sausages. Notably, microbial composition discrepancies between Sichuan and Guizhou sausages were primarily driven by processing conditions rather than regional climate factors. Collectively, these findings provide valuable insight for developing novel specific starters. Full article

Mangrove ecosystems are renowned for their rich fungal diversity, housing a plethora of multicellular fungi and yeasts. In this investigation, we examined the yeast diversity associated with various compartments (rhizospheric soil, stems, roots, leaves, barks, and flowers) of the widely distributed mangrove tree, Avicennia officinalis, from the Kumbalam and Puthuvype mangroves in central Kerala, India. Our study revealed that the yeast strains were not uniformly distributed in various compartments. The highest abundance of yeasts was found in leaves (42%), followed by sediment (21%), and the lowest in flowers (5%). Among the 45 isolates, 27% comprised red yeasts. Dominant genera included Rhodotorula (27.5%), Debaryomyces (17.6%), Kluyveromyces (5.9%), Cryptococcus (9.8%), and Candida (7.8%), while genera such as Geotrichum, Lodderomyces, Ogataea, Galactomyces, and Saitozyma were represented by single isolates. Certain yeast species, such as C. tropicalis and Rhodotorula paludegina, exhibited a cosmopolitan distribution in various plant compartments of A. officinalis. An analysis of the proximate composition of different plant compartments of A. officinalis revealed variations in C, N, S, H, Ca, K, and the C/N ratio. Interestingly, these variations were positively correlated with the yeast community composition, suggesting a potential role of the elemental composition of plants in shaping the yeast biome of A. officinalis. However, our understanding of the inter-relationships among yeast communities in different plant compartments remains limited, highlighting the need for further comprehensive investigations in this field. Full article

The rejection of chemical preservatives reflects the growing demand for natural and safe products. This concern has spurred scientific interest in yeasts as biocontrol agents, given their antagonistic activity against undesired fungi, which is one of the main problems associated with preservative reduction. Debaryomyces hansenii is a non-conventional yeast that has shown great potential for inhibiting filamentous fungi in the food industry. This study investigated the role of nutrient competition in the biocontrol activity of D. hansenii against unwanted molds. Potentially pathogenic molds from spoiled food were isolated using different media and identified using Sanger sequencing. The inhibitory effects of different autochthonous D. hansenii strains under varying nutrient conditions were assessed against isolated molds using semipermeable membranes. Inhibition activity was measured by assessing mycelial expansion and spore production using image software analysis and classical cell counting using a Neubauer chamber. The results indicated that D. hansenii effectively inhibited mold growth and sporulation, with the autochthonous strains LR2 and SRF1 showing higher inhibitory activity than the control strain CBS767. The effectiveness of inhibition varied with the yeast–mold combination, highlighting the need for a species-specific analysis. Nutrient competition plays a complementary role in D. hansenii biocontrol but does not directly impact overall inhibition. This suggests that other mechanisms, such as direct cell interactions or metabolite production, may be crucial. These findings enhance our understanding of the potential of D. hansenii as a natural preservative and advance biocontrol methods for food safety. Full article

Debaryomyces hansenii naturally colonize wheat grain and can potentially inhibit the pathogens responsible for Fusarium crown rot (FCR). Seed dressing is a recommended method for protecting crops against FCR pathogens. The effectiveness of seed dressing with antagonistic yeasts in reducing the incidence of FCR remains insufficiently investigated. The aim of this study was to evaluate the effect of seed dressing with a triazole fungicide and a suspension of D. hansenii cells on the health status and development of durum wheat cultivars (Durasol and Floradur), and to analyze the structure of the mycobiome in the rhizosphere of seedlings. Under field conditions, the incidence of FCR was reduced by 57.1% by triticonazole and 35.7% by the biocontrol agent relative to the control treatment. Seed dressing with D. hansenii decreased the number of operational taxonomic units (OTUs) of Fusarium pathogens by 47.24% in cv. Durasol and 87.4% in cv. Floradur. The number of OTUs of autochthonous yeast species and Mortierellomycota increased in the rhizosphere of both durum wheat cultivars. The effectiveness of seed dressing with yeasts is determined by the quality and local adaptation of biocontrol agents. Full article

Gle1 functions as a regulator of Dbp5, a DEAD-box-containing RNA helicase that is a component of the nuclear pore complex. In association with Gle1 and inositol hexakisphosphate (IP6), ADP-bound Dbp5 facilitates the release of RNA. The RNA-bound Dbp5 undergoes ATP hydrolysis and is activated by Gle1 in the presence of IP6. The formation of a ternary complex involving Dbp5, Gle1, and the nucleoporin Nup159 promotes ADP secretion and prevents RNA recombination. To date, several complex structures of Gle1 with its binding partners have been described; however, the structure of unbound Gle1 remains elusive. To investigate the structural features associated with complex formation, the crystal structure of N-terminally truncated Gle1 from Debaryomyces hansenii (DhGle1ΔN) was determined at a resolution of 1.5 Å. The DhGle1ΔN protein comprises 13 α-helices. Structural comparisons with homologs, all of which have been characterized in various complexes, revealed no significant conformational changes. However, several distinct secondary structural elements were identified in α1, α3, α4, and α8. This study may provide valuable insights into the architecture of yeast Gle1 proteins and their interactions with Dbp5, which is crucial for understanding the regulation of mRNA export. Full article

Dry-aged beef has gained interest worldwide in recent years due to its improved sensory attributes. This enhancement is thought to be partially driven by microbial activities, particularly lipolysis and proteolysis. In this study, dry-aged beef manufactured by seven commercial producers in China was analyzed. The pH value and total volatile base nitrogen value of dry-aged beef were determined. High-throughput amplicon sequencing of full-length 16S rRNA genes and internal transcribed spacer (ITS) regions was used to analyze the microbial community. A total of 207 proteolytic and lipolytic isolates were identified by sequencing 16S rRNA genes for bacteria and sequencing the D1/D2 region of 28S rRNA genes and the ITS region for fungi. The results revealed that the crust harbored greater numbers of bacteria and fungi than the interior. The bacterial community was dominated by Pseudomonas species, which were core members in both the crust and interior, while Brochothrix thermosphacta was identified as a core bacterium exclusively in the crust. The fungal community primarily constituted Candida sake, Kurtzmaniella species, and members of the phylum Chytridiomycota. Proteolytic and lipolytic isolates were mainly identified as Pseudomonas sp., B. thermosphacta, Carnobacterium maltaromaticum, Candida zeylanoides (teleomorph: Kurtzmaniella zeylanoides), C. sake, and Debaryomyces hansenii. Two strains of C. zeylanoides and C. sake exhibiting high proteolytic and lipolytic activities effectively hydrolyzed beef fat, myofibrillar protein, and sarcoplasmic protein. This study characterized the main microorganisms and their enzymatic functions associated with dry-aged beef, highlighting the need to explore their contributions to the sensory attributes of dry-aged beef. Full article

The effect of Debaryomyces hansenii SH4, a typical aroma enhancer, on flavor formation of the dry fermented sausage was investigated using gas chromatography-mass spectrometry and metagenomic sequencing. The results showed that inoculation with D. hansenii SH4 promoted volatile compound formation from carbohydrate and amino acid metabolism and accelerated ester synthesis. The enzymes, genes, and microorganisms involved in the formation pathway of volatile compounds based on microbial metabolism were predicted and constructed into a metabolic pathway network. D. hansenii, Lactobacillus curvatus, Lactobacillus sakei, Lactobacillus plantarum, Leuconostoc fallax, Weissella minor, and Staphylococcus and Candida species were found to be the predominant functional microbes for flavor development in dry sausage. This study established a new insight into the metagenome-based bioinformatic effects of D. hansenii SH4 as a starter culture on the microbial synthesis of key volatile compounds in dry sausage. Full article

Amasi, a traditional fermented milk produced in Southern Africa, is associated with several health benefits, such as probiotic activities, immune system modulation, and pharmacological (antimicrobial, antitumor and antioxidant) potential. This study investigated the microbial diversity in Amasi (produced from cow’s and goat’s milk) through targeted metagenomic bacterial 16S rRNA and fungal ITS sequencing, the metabolic functional prediction of Amasi samples using the Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) and profiled amino acids constituents using Liquid Chromatographic-Mass Spectrophotometry (LC-MS). The results obtained revealed Firmicutes, Bacteroidetes, and Proteobacteria as the most prevalent bacterial phyla, with Lactococcus and Lactobacillus being the most abundant genera. On the other hand, Ascomycota, Basidiomycota, and Mucoromycota were the main fungal phyla, while Aspergillus, Kazachstania, and Debaryomyces spp. dominated the fungal genera. Also, Pseudomonas spp., Bacillus spp., Clostridium spp., Cronobacter spp., Alternaria spp., Diaporthe spp., and Penicillium spp. were the probable pathogenic bacteria and fungi genera found, respectively. Atopobium, Synechococcus, and Parabacteroides were found less often as rare genera. It was found that the amino acid and drug metabolism pathway prediction values in Amasi samples were significantly higher (p < 0.05) than in raw cow and goat milk, according to the inferred analysis (PICRUSt). The amino acid validation revealed glutamine and asparagine values as the most significant (p < 0.05) for Amasi cow milk (ACM) and Amasi goat milk (AGM), respectively. Comparatively, ACM showed more microbial diversity than AGM, though there were relative similarities in their microbiome composition. PICRUSt analysis revealed significant metabolites in the two Amasi samples. Overall, data from this study showed heterogeneity in microbial diversity, abundance distributions, metabolites, and amino acid balance between raw cow/goat milk and Amasi samples. Full article

Porcine blood, a significant byproduct of the pork industry, represents a potential source of antimicrobial peptides (AMPs). AMPs offer a promising alternative to chemical antimicrobials, which can be used as natural preservatives in the food industry. AMPs can exhibit both antibacterial and/or antifungal properties, thus improving food safety and addressing the growing concern of antibiotic and antifungal resistance. The objective of this study was to evaluate the antimicrobial activity of potential AMPs previously identified from porcine cruor hydrolysates. To this end, a total of sixteen peptides were chemically synthesized and their antimicrobial activities (antibacterial, anti-mold, and anti-yeast) were evaluated using microtitration and agar well diffusion methods against a wide range of microorganisms. Five new peptide sequences demonstrated antifungal activity, with Pep5 (FQKVVAGVANALAHKYH), an alpha-helix peptide, exhibiting the most promising results. Pep5 demonstrated efficacy against nine of the eleven fungal isolates, exhibiting low minimum inhibitory concentrations (MICs) and a fungicidal effect against key spoilage fungi (Rhodotorula mucilaginosa, Debaryomyces hansenii, Candida guilliermondii, Paecilomyces spp., Eurotium rubrum, Mucor racemosus, Aspergillus versicolor, Penicillium commune, and P. chrysogenum). These findings illustrate the potential of porcine blood hydrolysates as a source of AMPs, particularly antifungal peptides, which are less known and less studied than the antibacterial ones. Among the tested sequences, Pep5 exhibited the most promising characteristics, including broad-spectrum activity, low MICs, and a fungicidal effect. It is, therefore, a promising candidate for further research and for potential applications in the porcine industry and beyond. Full article

The microbial community of a soy sauce is one of the most important factors in determining the sensory characteristics of that soy sauce. In this study, the microbial communities and sensory characteristics of twenty samples of Korean soy sauce (ganjang) were investigated using shotgun metagenome sequencing and descriptive sensory analysis, and their correlations were explored by partial least square (PLS) regression analysis. The metagenome analysis identified 1332 species of bacteria, yeasts, molds, and viruses across 278 genera, of which Tetragenococcus, Bacillus, and Enterococcus accounted for more than 80% of the total community. In the fungal community, Zygosaccharomyces rouxii, Candida versatilis, Rhodotorula taiwanensis, Debaryomyces hansenii, and Aspergillus oryzae were dominant, while the viral community consisted entirely of bacteriophages, with Bacillus phages SIOphi accounting for 93%. According to the results of the PLS analysis, desirable sensory characteristics, such as umami, sweet, and roasted soybean, as well as preference, were associated with Tetragenococcus, Lysinibacillus, Enterococcus, Staphylococcus, Lactobacillus, Pediococcus, and Weissella. The musty flavor, which is a typical property of traditional fermented foods, was related to Halomonas and Psychrobacte, while the bitter, acrid taste and sour smell were closely associated with Chromohalobacter. The results of this study provide comprehensive information on the microbial community of ganjang and may be used to select starter cultures for soy sauces. Full article

Polycyclic aromatic hydrocarbons (PAHs) are toxic organic compounds produced during the incomplete combustion of organic materials and are commonly found in the environment due to anthropogenic activities such as industrial and vehicular emissions as well as natural sources, mainly volcanic eruptions and forest fires. PAHs are well known for their bioaccumulative capacity and environmental persistence, raising concerns due to their adverse effects on human health, including their carcinogenic potential. In recent years, bioremediation has emerged as a promising, effective, and sustainable solution for the degradation of PAHs in contaminated environments. In this context, yeasts have proven to be key microorganisms in the degradation of these compounds, owing to their ability to metabolize them through a series of enzymatic pathways. This review explores the advancements in yeast-mediated degradation of PAHs, with a particular focus on the role of enzymes such as cytochrome P450 (CYPs), epoxide hydrolases (EHs), and glutathione S-transferases (GSTs), which facilitate the breakdown of these compounds. The review also discusses the applications of genetic engineering to enhance the efficiency of yeasts in PAH degradation and the use of omics technologies to predict the catabolic potential of these organisms. Additionally, it examines studies addressing the degradation of benzo[a]pyrene (BaP) by yeasts such as Debaryomyces hansenii, and the potential future implications of omics sciences for developing new bioremediation. Full article

The use of probiotics has been gaining popularity in terms of inclusion into human diets over recent years. Based on properties exerted by these organisms, several benefits have been elucidated and conferred to the host. Bacteria have been more commonly used in probiotic preparations compared to yeast candidates; however, yeast exhibit several beneficial properties, such as the prevention and treatment of diarrhea, the production of antimicrobial agents, the prevention of pathogen adherence to intestinal sites, the maintenance of microbial balance, the modulation of the immune system, antibiotic resistance, amongst others. Saccharomyces boulardii is by far the most studied strain; however, the potential for the use of other yeast candidates, such as Kluyveromyces lactis and Debaryomyces hansenii, amongst others, have also been evaluated in this review. Furthermore, a special focus has been made regarding the production considerations for yeast-based probiotics and their formulation into different delivery formats. When drafting this review, evidence suggests that the use of yeasts, both wild-type and genetically modified candidates, can extend beyond gut health to support skin, the respiratory system, and overall immune health. Hence, this review explores the potential of yeast probiotics as a safe, effective strategy for preventative health in humans, highlighting their mechanisms of action, clinical applications, and production considerations. Full article