Biology subjects

Ragyak, A.

Publications and source records attributed to Ragyak, A..

3 recordsLinked to original sources

bioRxiv2023

Comparative transcriptional analysis of Candida auris biofilms following farnesol and tyrosol treatment

Candida auris is frequently associated with biofilm-related invasive infections. The resistant profile of these biofilms necessitates innovative therapeutic options, where quorum sensing may be a potential target. Farnesol and tyrosol are two fungal quorum-sensing molecules with antifungal effects at supraphysiological concentrations. To date there has been no high-throughput comparative molecular analysis regarding the background of farnesol- or tyrosol-related effects against C. auris biofilms. Here, we performed genome-wide transcript profiling with C. auris biofilms following 75 M farnesol or 15 mM tyrosol exposure using transcriptome sequencing (RNA-Seq). The analysis highlighted that the number of up-regulated genes (a minimum 1.5-fold increase) was 686 and 138 for tyrosol and farnesol, respectively, while 662 and 199 genes were down-regulated (a minimum 1.5-fold decrease) for tyrosol and farnesol, respectively. The overlap between tyrosol- and farnesol-responsive genes was considerable (101 and 116 overlapping up-regulated and down-regulated genes, respectively). Genes involved in biofilm events, glycolysis, ergosterol biosynthesis, fatty acid oxidation, iron metabolism, and autophagy were primarily affected in treated cells. Farnesol caused an 89.9%, 73.8%, and 32.6% reduction in the calcium, magnesium, and iron content, respectively, whereas tyrosol resulted an 82.6%, 76.6%, and 81.2% decrease in the calcium, magnesium, and iron content compared to the control, respectively. Moreover, the complexation of farnesol, but not tyrosol, with ergosterol is impeded in the presence of exogenous ergosterol, resulting in a minimum inhibitory concentration increase in the quorum-sensing molecules. This study revealed several farnesol- and tyrosol-specific responses, which will contribute to the development of alternative therapies against C. auris biofilms. ImportanceCandida auris is a multidrug-resistant fungal pathogen, which is frequently associated with biofilm related infections. Candida-derived quorum-sensing molecules (farnesol and tyrosol) play a pivotal role in the regulation of fungal morphogenesis and biofilm development. Furthermore, they may have remarkable anti-biofilm effects, especially at supraphysiological concentrations. Innovative therapeutic approaches interfering with quorum-sensing may be a promising future strategy against C. auris biofilms; however, limited data are currently available concerning farnesol-induced and tyrosol-related molecular effects in C. auris. Here, we detected several genes involved in biofilm events, glycolysis, ergosterol biosynthesis, fatty acid oxidation, iron metabolism, and autophagy, which were primarily influenced following farnesol or tyrosol exposure. Moreover, calcium, magnesium, and iron homeostasis were also significantly affected. These results reveal molecular events that provide definitive explanations for the observed anti-biofilm effect; furthermore, they support the development of novel therapeutic approaches against C. auris biofilms.

microbiology↗

bioRxiv2022

Physiological and transcriptional profiling of surfactin exerted antifungal effect against Candida albicans

Given the risk of Candida albicans overgrowth in the gut, novel complementary therapies should be developed to reduce fungal dominancy. This study highlights the antifungal characteristics of a Bacillus subtilis-derived secondary metabolite, surfactin with high potential against C. albicans. Surfactin inhibited the growth of C. albicans following a 1-hour exposure, in addition to reduced adhesion and morphogenesis. Specifically, surfactin did not affect the level of reactive oxygen species but increased the level of reduced glutathione. Surprisingly, ethanol production enhanced following 2 hours of surfactin exposure. Surfactin treatment caused a significant reduction in intracellular iron, manganese and zinc content compared to control cells, whereas the level of copper was not affected. Alongside these physiological properties, surfactin also enhanced fluconazole efficacy. To gain detailed insights into the surfactin-related effects on C. albicans, genome-wide gene transcription analysis was performed. Surfactin treatment resulted in 1390 differentially expressed genes according to total transcriptome sequencing (RNA-Seq). Of these, 773 and 617 genes with at least a 1.5-fold increase or decrease in transcription, respectively, were selected for detailed investigation. Several genes involved in morphogenesis or related to metabolism (e.g., glycolysis, fermentation, fatty acid biosynthesis) were down-regulated. Moreover, surfactin decreased the expression of ERG1, ERG3, ERG9, ERG10 and ERG11 involved in ergosterol synthesis, whereas genes associated with ribosome biogenesis and iron metabolism and drug transport-related genes were up-regulated. Our data demonstrate that surfactin significantly influences the physiology and gene transcription of C. albicans, and could contribute to the development of a novel innovative complementary therapy. ImportanceAlthough gut colonization by Candida albicans can be considered normal, it may be associated with intestinal diseases. Furthermore, Candida dominance in the gut may pose a potent risk for systemic candidiasis, especially for immunocompromised individuals. In recent years, interest has been growing for the use of Bacillus subtilis as a safe and effective probiotic for human healthcare. Surfactin is a B. subtilis-derived lipopeptide with potential antifungal activity; however, the mechanism underlying this remains unknown. In this study, surfactin negatively affected the adherence, morphogenesis and metabolism of C. albicans and increased ethanol production. These were associated with a reduction in intracellular iron, manganese and zinc while the copper content was not affected. Alongside these physiological modulations, surfactin also had a potent synergistic effect on fluconazole. Our results provide a definitive explanation for the surfactin-related antifungal effect of B. subtilis; furthermore, these data provide a good basis for future probiotic development.

microbiology↗

bioRxiv2021

Transcriptional profiling of the Candida auris response to exogenous farnesol exposure

The antifungal resistance threat posed by Candida auris necessitates bold and innovative therapeutic options. Farnesol, a quorum-sensing molecule with a potential antifungal and/or adjuvant effect; it may be a promising candidate in alternative treatment regimens. To gain further insights into the farnesol-related effect on C. auris, genome-wide gene expression analysis was performed using RNA-Seq. Farnesol exposure resulted in 1,766 differentially expressed genes. Of these, 447 and 304 genes with at least 1.5-fold increase or decrease in expression, respectively, were selected for further investigation. Genes involved in morphogenesis, biofilm events (maturation and dispersion), gluconeogenesis, iron metabolism, and regulation of RNA biosynthesis showed down-regulation, whereas those related to antioxidative defense, transmembrane transport, glyoxylate cycle, fatty acid {beta}-oxidation, and peroxisome processes were up-regulated. In addition, farnesol treatment increased the expression of certain efflux pump genes, including MDR1, CDR1, and CDR2. Growth, measured by change in CFU number, was significantly inhibited within 2 hours of the addition of farnesol (5.8x107{+/-}1.1x107 and 1.1x107{+/-}0.3x107 CFU/ml for untreated control and farnesol-exposed cells, respectively) (p<0.001). In addition, farnesol treatment caused a significant reduction in intracellular iron (152.2{+/-}21.1 vs. 116.0{+/-}10.0 mg/kg), manganese (67.9{+/-}5.1 vs. 18.6{+/-}1.8 mg/kg), and zinc (787.8{+/-}22.2 vs. 245.8{+/-}34.4 mg/kg) (p<0.05-0.001) compared to untreated control cells, whereas the level of cooper was significantly increased (274.6{+/-}15.7 vs. 828.8{+/-}106.4 mg/kg) (p<0.001). Our data demonstrate that farnesol significantly influences the growth, intracellular metal ion contents, and gene expression related to fatty acid metabolism, which could open new directions in developing alternative therapies against C. auris. ImportanceCandida auris is a dangerous fungal pathogen that causes outbreaks in health care facilities, with infections associated with high mortality rate. As conventional antifungal drugs have limited effects against the majority of clinical isolates, new and innovative therapies are urgently needed. Farnesol is a key regulator molecule of fungal morphogenesis, inducing phenotypic adaptations and influencing biofilm formation as well as virulence. Alongside these physiological modulations, it has a potent antifungal effect alone or in combination with traditional antifungals, especially at supraphysiological concentrations. However, our knowledge about the mechanisms underlying this antifungal effect against C. auris is limited. This study has demonstrated that farnesol enhances the oxidative stress and reduces the fungal survival strategies. Furthermore, it inhibits manganese, zinc transport, and iron metabolism as well as increases fungal intracellular copper content. In addition, metabolism was modulated towards {beta}-oxidation. These results provide definitive explanations for the observed antifungal effects.

microbiology↗