Phaffia Rhodozyma Research Articles

Yeast need not be used only in beer production. I. The carotenoid astaxanthin produced by yeast.

Carotenoids are produced by photosynthesizing organisms, i.e. plants and algae, as well as some bacteria, protists and fungi. Their role lies mainly in the function of complementary photosynthetic pigments and antioxidants. Carotenoids are distinguished according to their structure into carotenoids of the hydrocarbon type, e.g. α-, β- and γ-carotene and oxygen derivatives – xanthophylls, among which astaxanthin, which excels in its antioxidant and nutraceutical properties, is the most important. It is used as a dietary supplement both in human nutrition and in the aquaculture and poultry industry, as a nutritional supplement in salmonid and hen farming. Many works have focused on the search for natural sources of astaxanthin as an alternative to synthetic astaxanthin. In nature, very few astaxanthin producing organisms are known in non-minor amounts, with green alga Haematococcus pluvialis and the yeast Xanthophyllomyces dendrorhous (anamorph Phaffia rhodozyma) being the most promising microorganisms for the biotechnological production of this xanthophyll. In this review we focus on the biosynthesis and carotenogenesis including the regulation mechanisms, generation of hyperproducing mutants by random mutagenesis and, last but not least, also metabolic engineering (genetic techniques). Attention is also paid to the optimization of fermentation conditions.

Atmospheric and room temperature plasma mutagenesis and astaxanthin production from sugarcane bagasse hydrolysate by Phaffia rhodozyma mutant Y1

In this study, atmospheric and room temperature plasma and ultraviolet mutagenesis was studied for astaxanthin overproducing mutant. Phaffia rhodozyma mutant Y1 was obtained from the selection plate with 120 μmol/L diphenylamine as selection agent, and its carotenoid concentration and content were 54.38 mg/L and 5.38 mg/g, which were 19.02 % and 21.20 % higher than that of the original strain, respectively. Sugarcane bagasse hydrolysate was used for astaxanthin production by mutant Y1 at 22 °C and 220 rpm for 96 h, and the biomass and carotenoid concentration reached 12.65 g/L and 88.57 mg/L, respectively. Ultrasonication and cellulase were used to break cell wall and the parameters were optimized, achieving an astaxanthin extraction rate of 96.01 %. The present work provided a novel combined mutagenesis method for astaxanthin overproducing mutant and a green cell wall disruption process for astaxanthin extraction, which would play a solid foundation on the development of natural astaxanthin.

Effect of different sugar sources on P. rhodozyma Y1654 growth and astaxanthin production

Phaffia rhodozyma (also known as Xanthophyllomyces dendrorhous) is one of the most promising natural sources of commercial astaxanthin. It has high growth rates, easy cultivation conditions and able to utilize different carbon substrates. This provides an opportunity to further lower production cost by using industrial waste such as molasses. This research therefore evaluates the growth dynamic and astaxanthin production of P. rhodozyma Y1654 growing on soy and sugar beet molasses-based media. Liquid growth media based on soy molasses (SM), sugar beet molasses (SBM) and glucose (control) as main sugar source with peptone and yeast extract supplementation were inoculated with 48 h old seed culture (grown in standard glucose media: 2.0% glucose, 1.0% peptone, 0.2% yeast extract) and incubated at 20 °C with stirring speed of 180 rpm for 7 days. Samples were taken daily throughout the study period to assess; cell count, dry cell weight (DCW) and amount of astaxanthin. Soy molasses-based media resulted in the highest biomass yield (7.7 g L) followed by SBM (5.8 g L). Generally, more than 90% of initial fermentable sugar was consumed at the end of the study. However, about 40% of total sugar in SM was unassimilable by P. rhodozyma Y1654. The highest astaxanthin yield was observed in the control media (77 µg g of DCW). Cultivation of P. rhodozyma Y1654 in SBM resulted in as much as twice (32.8 µg g of DCW) the astaxanthin yield of SM (12.4 µg g DCW). Molasses-based media are good for growth of P. rhodozyma Y1654 but for astaxanthin production, they need further optimization.

Enhancement of carotenoid biosynthesis in Phaffia rhodozyma PR106 under stress conditions.

Carotenoids have good biological activity in antioxidant, anti-aging and scavenging harmful free radicals. In this study, we screened a strain that produced carotenoids, and selected a stress condition which significantly improved carotenoids content. The strain was identified as Phaffia rhodozyma PR106. Active oxygen generator TiO2 was the most significant factor to the carotenoids content of the P. rhodozyma. The content of carotenoids was 54.45 mg/g at 500 mg/L TiO2, which was about 1.25 times of the control and the proportion of carotenoids also changed from 1:9:16 to 1:8.5:12. Further, we determined the reactive oxygen species (ROS) in YEPD medium and P. rhodozyma, found that the ROS (H2O2, O2-, and HO•) was significantly increased at 500 mg/L TiO2 in YEPD medium compared with the control, but increased in P. rhodozyma under 1000 mg/L TiO2 treated. These results suggested that the increase in carotenoids was related to ROS in P. rhodozyma.

Mrakia fibulata sp. nov., a psychrotolerant yeast from temperate and cold habitats.

Tree fluxes are sugar-rich, sometimes ephemeral, substrates occurring on sites where tree sap (xylem or phloem) is leaking through damages of tree bark. Tree sap infested with microorganisms has been the source of isolation of many species, including the biotechnologically relevant carotenoid yeast Phaffia rhodozyma. Tree fluxes recently sampled in Germany yielded 19 species, including several psychrophilic yeasts of the genus Mrakia. Four strains from tree fluxes represented a potential novel Mrakia species previously known from two isolates from superficial glacial melting water of Calderone Glacier (Italy). The Italian isolates, originally identified as Mrakia aquatica, and two strains from Germany did not show any sexual structures. But another culture collected in Germany produced clamped hyphae with teliospores. A detailed examination of the five isolates (three from Germany and two from Italy) proved them to be a novel yeast species, which is described in this manuscript as Mrakia fibulata sp. nov. (MB 830398), holotype DSM 103931 and isotype DBVPG 8059. In contrast to other sexually reproducing Mrakia species, M. fibulata produces true hyphae with clamp connections. Also, this is the first psychrotolerant Mrakia species which grows above 20°C. Spring tree fluxes are widespread and can be recognized and sampled by amateurs in a Citizen Science project. This substrate is a prominent source of yeasts, and may harbor unknown species, as demonstrated in the present work. The description of Mrakia fibulata is dedicated to our volunteer helpers and amateurs, like Anna Yurkova (9-years-old daughter of Andrey Yurkov), who collected the sample which yielded the type strain of this species.

Effects of astaxanthin produced by Phaffia rhodozyma on growth performance, antioxidant activities, and meat quality in Pekin ducks

This study was conducted to determine the effect of astaxanthin (AX) produced by Phaffia rhodozyma (PR) on growth performance, antioxidant activities, relative organ weight, and meat quality in Pekin ducks. A total of 1,440 female one-day-old Pekin ducklings (52.3 ± 0.4g) were blocked based on body weight (BW), and randomly allotted to 3 treatments with 8 replicates of 60 birds each. The experiment lasted for 6 wk, and dietary treatments included corn-soybean meal-based diet supplemented with 0, 0.15, and 0.3% PR. The supplementation of AX increased (P<0.05) body weight gain (BWG) linearly and reduced (P<0.05) feed-to-gain ratio (F/G) linearly during days 22 to 42. BWG and final BW was increased (P<0.05) linearly by AX supplementation throughout the experiment. The inclusion of AX increased (P<0.05) superoxide dismutase, glutathione peroxidase, total antioxidative capacity, and interleukin-6 in the serum linearly, as well as decreased (P<0.05) serum malondialdehyde linearly. The relative weight of abdominal fat was increased (P<0.05) linearly by AX supplementation. The inclusion of AX decreased (P<0.05) cook loss linearly, but increased (P<0.05) pH24h, water holding capacity and redness (a*) linearly. Taken together, the supplementation of AX (3.458 or 6.915mg/kg diet) from PR improved final BW, BWG during days 22 to 42 and 1 to 42 and reduced F/G during days 22 to 42, as well as caused positive effects on antioxidant function and meat quality.

Xylose-Enriched Ethanol Fermentation Stillage from Sweet Sorghum for Xylitol and Astaxanthin Production

Developing integrated biorefineries requires the generation of high-value co-products produced alongside cellulosic ethanol. Most industrial yeast strains produce ethanol at high titers, but the small profit margins for generating ethanol require that additional high-value chemicals be generated to improve revenue. The aim of this research was to boost xylose utilization and conversion to high-value co-products that can be generated in an integrated biorefinery. Pretreated sweet sorghum bagasse (SSB) was hydrolyzed in sweet sorghum juice (SSJ) followed by ethanol fermentation. Ethanol was removed from the fermentation broth by evaporation to generate a stillage media enriched in xylose. Candida mogii NRRL Y-17032 could easily grow in non-detoxified stillage media, but a high xylitol yield of 0.55 g xylitol/g xylose consumed was achieved after recovered cells were resuspended in synthetic media containing supplemented xylose. Phaffia rhodozyma ATCC 74219 could be cultivated in non-detoxified stillage media, but astaxanthin generation was increased 4-fold (from 17.5 to 71.7 mg/L) in detoxified media. Future processing strategies to boost product output should focus on a two-step process where the stillage media is used as the growth stage, and a synthetic media for the production stage utilizing xylose generated from SSB through selective hemicellulase enzymes.

Astaxanthin sources: Suitability for human health and nutrition

Background: Astaxanthin (AX) has been consumed as a nutritional supplement for approximately twenty years. The primary source has been a natural plant-based supplement from the single-cell alga Haematococcus pluvialis (NAT-AX). Recently, Astaxanthin from other sources has entered the marketplace. The primary alternative source in the human nutritional supplement market has been a synthetic form of Astaxanthin produced from petrochemicals (SYN-AX). Additionally, a very small amount of Astaxanthin from a genetically-manipulated yeast Xanthophyllomyces dendrorhous (former nomenclature Phaffia rhodozyma, still commonly referred to as “Phaffia”) (PH-AX) is also available in some supplement products. The three forms have substantial chemical differences. In addition to the chemical differences between sources of AX, in-vitro research has demonstrated profound differences in antioxidant strength and animal research has revealed fundamental differences in health benefits. In all cases, NAT-AX has proven more biologically active than the other sources. This review is designed to assist readers in understanding which form(s) of AX are suitable for consumers desiring preventive or therapeutic health benefits. Results: In head-to-head antioxidant experiments, NAT-AX demonstrated 14X to 90X greater antioxidant activity than SYN-AX. In numerous animal trials in diverse species, NAT-AX in esterified form has demonstrated superior efficacy in increasing lifespan; treating skin cancer; preventing the formation of gastric ulcers; improving resistance to stress; decreasing reactive oxygen species (ROS); increasing retinol conversion in the liver; augmenting enzyme levels; increasing growth rates; and improving exercise endurance.From a safety perspective, NAT-AX has been the subject of human clinical trials demonstrating safety and a wide variety of health benefits. In addition, no documented adverse events have surfaced during its twenty years of distribution as a food supplement for humans. SYN-AX and PH-AX have not been proven safe for direct human consumption and have not demonstrated any health benefits in clinical trials. Due to these facts, SYN-AX and PH-AX have not been allowed for human consumption by government regulators in many countries while NAT-AX is widely accepted in most countries around the world. Conclusion: Based on our review of the literature below, we recommend NAT-AX as the sole form of AX for human consumption until SYN-AX and PH-AX have been proven safe and efficacious through human clinical research.

Deregulation of phytoene-\u03b2-carotene synthase results in derepression of astaxanthin synthesis at high glucose concentration in Phaffia rhodozyma astaxanthin-overproducing strain MK19

BackgroundA major obstacle to industrial-scale astaxanthin production by the yeast Phaffia rhodozyma is the strong inhibitory effect of high glucose concentration on astaxanthin synthesis. We investigated, for the first time, the mechanism of the regulatory effect of high glucose (> 100 g/L) at the metabolite and transcription levels.ResultsTotal carotenoid, β-carotene, and astaxanthin contents were greatly reduced in wild-type JCM9042 at high (110 g/L) glucose; in particular, β-carotene content at 24–72 h was only 14–17% of that at low (40 g/L) glucose. The inhibitory effect of high glucose on astaxanthin synthesis appeared to be due mainly to repression of lycopene-to-β-carotene and β-carotene-to-astaxanthin steps in the pathway. Expression of carotenogenic genes crtE, pbs, and ast was also strongly inhibited by high glucose; such inhibition was mediated by creA, a global negative regulator of carotenogenic genes which is strongly induced by glucose. In contrast, astaxanthin-overproducing, glucose metabolic derepression mutant strain MK19 displayed de-inhibition of astaxanthin synthesis at 110 g/L glucose; this de-inhibition was due mainly to deregulation of pbs and ast expression, which in turn resulted from low creA expression. Failure of glucose to induce the genes reg1 and hxk2, which maintain CreA activity, also accounts for the fact that astaxanthin synthesis in MK19 was not repressed at high glucose.ConclusionWe conclude that astaxanthin synthesis in MK19 at high glucose is enhanced primarily through derepression of carotenogenic genes (particularly pbs), and that this process is mediated by CreA, Reg1, and Hxk2 in the glucose signaling pathway.

Phaffia rhodozyma cultivation on structural and non-structural sugars from sweet sorghum for astaxanthin generation

ABSTRACT Because it contains both structural and non-structural sugars, sweet sorghum has potential applications in biorefineries seeking to produce co-products. Differences between sugar composition in sweet sorghum juice (SSJ) and sweet sorghum bagasse (SSB) requires a robust organism that can be cultivated in both sources. The red pigmented yeast strain Phaffia rhodozyma can be grown indiscriminately on sugars originating from agricultural feedstocks and produces the carotenoid astaxanthin which has applications in high value markets. In this study we determined cultivating conditions for Phaffia rhodozyma in both SSJ and SSB hydrolysate for biomass growth and astaxanthin generation. Batch bioreactor studies on SSJ with supplementation produced 34.9 g/L biomass with 53.3 mg/L astaxanthin at a productivity rate of 0.352 mg/L/h after 168 hours of cultivation. Phaffia cultivated in SSB hydrolysate showed improved growth after activated carbon (AC) detoxification and only marginal improvement after laccase detoxification. AC detoxification produced 23.6 g/L biomass, 48.89 mg/L astaxanthin, and a productivity of 0.291 mg/L/h. Undiluted SSB hydrolysate produced inferior results due to the assumed presence of phenolic inhibitors. While both structural and non-structural sugars from sweet sorghum can be utilized by Phaffia rhodozyma , it is apparent that SSJ provides a better substrate to produce naturally occurring astaxanthin.

Use of Low-Cost Agro-Industrial Substrate to Obtain Carotenoids from Phaffia rhodozyma in a Bioreactor

Abstract The aim of this work was to evaluate the production of carotenoids from red yeast Phaffia rhodozyma in a bioreactor using agro-industrial wastes. This study used a sequential strategy of e...

Preparation of astaxanthin mask from Phaffia rhodozyma and its evaluation

Abstract As a powerful antioxidant, astaxanthin (AST) is increasingly used in the cosmetic industry. At present, masks with natural extracts are generally accepted by consumers. This study envisaged the development of astaxanthin stock solution and astaxanthin mask using the astxanthin from Phaffia rhodozyma. The concentration and stability of astaxanthin from P. rhodozyma were evaluated in several cosmetic solvents. Caprylic/capric triglyceride (GTCC) was found to be suitable solvent to prepare astaxanthin stock solution (AST-GTCC). The formula to produce astaxanthin mask using AST-GTCC was developed. Compared with vitamin E (VE), both AST-GTCC and astaxanthin mask showed superior DPPH-scavenging activity, indicating that they had strong antioxidant capabilities. The stability of AST-GTCC and mask was evaluated and their optimal conditions of production and storage were determined. The suggested content of astaxanthin in the mask and the storage temperature were 20 ppm and 4 °C, respectively, with half-life of 70.7 weeks for AST-GTCC mask. The present study suggested that the developed process is feasible, and the mask is promising in the cosmetic market.

Selection of bacterial strains belonging to the astaxanthin producing Paracoccus genus

Astaxanthin, a member of the carotenoid group, is an important additive not only in feed nutrition but also in providing the red color of salmon meat, cooked shellfish and koi fish. This leads to an increase in the commercial and aesthetic values for those aquatic products. In addition, astaxanthin is widely used in the food, pharmaceutical and cosmetic industries. Nowadays, astaxanthin has been mainly extracted from Haematococcus pluvialis and Phaffia rhodozyma. Moreover, some bacterial groups, especially Paracoccus genus including P. carotinifaciens, and P. haeundaensis have also been reported to synthesize a high level of astaxanthin. In this study, a number of bacterial strains belonging to Paracoccus genus isolated from several in-shore regions of Vietnam have been screened to find high astaxanthin producing strains for aquatic feed production. More than 90 colourful biosynthesis strains were isolated from 50 soil and water samples in different beaches and ramsa, of which 33 strains belong to negative bacterial group. Analysis of the extracted carotenoid mixtures obtained from the pellets of those strains by UV-Vis spectrophotometer and TLC reveals that 3 strains including C32, C38 and C47 are able to yield a high level of astaxanthin at 23 mg, 18 mg, and 11 mg astaxanthin per 1 g biomass, respectively. Based on the physiological, biochemical and 16S rRNA gene sequence, the C32 and C38 strains are most related to P. carotinifaciens whereas the C47 strain is most closely to P. kocurii.

Mechanistic investigations in ultrasound-assisted extraction of astaxanthin from Phaffia rhodozyma MTCC 7536

This study has dealt with physical mechanism of ultrasound-assisted astaxanthin extraction from dry cell mass (DCM) of Phaffia rhodozyma. Preliminary experiments for screening of extraction solvent revealed highest extraction yield for acetone. Further experiments were performed using mixtures of DMSO and acetone with varying compositions as extraction solvent. The results were analyzed in concurrence with prediction of astaxanthin solubility using UNIFAC (Universal Quasi-Chemical Functional-Group Activity Coefficients) method and simulations of cavitation bubble dynamics. The highest astaxanthin yield of 1536 ± 3 μg/g DCM was obtained for solvent comprising 33% v/v DMSO + 67% v/v acetone. UNIFAC predicted astaxanthin solubility (1.57 g/L) was also highest for this composition, although the convection intensity predicted by bubble dynamics simulations was relatively low. Astaxanthin yield reduced with further increase in DMSO volume fraction in solvent. This result has pointed towards dominant role of solubility of solute rather than intensity of convection in extraction mixture in the extraction yield of astaxanthin.

Disruption of Phaffia rhodozyma cells and preparation of microencapsulated astaxanthin with high water solubility.

A novel process was developed for encapsulation of astaxanthin from Phaffia rhodozyma. The yeast cells were disrupted by glass beads and the high shearing force partially emulsified the astaxanthin in aqueous phase. The enzymolysis method was then adopted to prepare the yeast extract for a full use of the cells. The gelatin and porous starch were used to microencapsulate the emulsified astaxanthin. Under optimized conditions, the recovery of amino nitrogen and solid reached 3.68 ± 0.32% and 49.22 ± 2.34%, respectively. The microencapsulation conditions were optimized through orthogonal experiment and the encapsulation efficiency, loading astaxanthin, and amino-nitrogen reached 88.56%, 1.55mg/g, and 1.35 ± 0.14%, respectively. The water solubility of microcapsules reached 81.5 ± 0.35%. Color and storage stability analysis showed that microencapsulation of astaxanthin possessed higher thermal stability. The results demonstrated that the established process was effective and practical.

Inhibitory effect of astaxanthin on pancreatic lipase with inhibition kinetics integrating molecular docking simulation

Astaxanthin is a natural pigment that possesses benefit potentials to prevent obesity, however, its underlying mechanism is not clarified. In the current study, Phaffia rhodozyma astaxanthin was prepared and its inhibitory effect on pancreatic lipase was evaluated. The results showed that astaxanthin significantly inhibited the activity of pancreatic lipase in a dose-dependent manner within the tested concentration ranges. The kinetic analysis demonstrated that astaxanthin noncompetitively inhibited pancreatic lipase activity. In addition, astaxanthin induced secondary structure changes which resulted in decreased enzyme activities. Furthermore, the molecular docking analysis revealed that astaxanthin blocked the channel of catalytic site to delay substrate entrance or prevent product diffusion through changing the catalytic site conformation. These findings not only shed light on the underlying inhibitory mechanism of astaxanthin on pancreatic lipase, but also provide scientific evidence for extending the application of astaxanthin in functional food industries.

Immobilization of the β-fructofuranosidase from Xanthophyllomyces dendrorhous by Entrapment in Polyvinyl Alcohol and Its Application to Neo-Fructooligosaccharides Production

The β-fructofuranosidase (Xd-INV) from the basidiomycota yeast Xanthophyllomyces dendrorhous (formerly Phaffia rhodozyma) is unique in its ability to synthesize neo- fructooligosaccharides (neo-FOS). In order to facilitate its industrial application, the recombinant enzyme expressed in Pichia pastoris (pXd-INV) was immobilized by entrapment in polyvinyl alcohol (PVA) hydrogels. The encapsulation efficiency exceeded 80%. The PVA lenticular particles of immobilized pXd-INV were stable up to approximately 40 °C. Using 600 g/L sucrose, the immobilized biocatalyst synthesized 18.9% (w/w) FOS (59.1 g/L of neokestose, 30.2 g/L of 1-kestose, 11.6 g/L of neonystose and 12.6 g/L of blastose). The operational stability of PVA-immobilized biocatalyst was assayed in a batch reactor at 30 °C. The enzyme preserved its initial activity during at least 7 cycles of 26 h.

Astaxanthin from Phaffia rhodozyma: Microencapsulation with carboxymethyl cellulose sodium and microcrystalline cellulose and effects of microencapsulated astaxanthin on yogurt properties

In this study, the astaxanthin from Phaffia rhodozyma was encapsulated with carboxymethyl cellulose sodium (CMC-Na) and microcrystalline cellulose (MCC) by freeze-drying and used in yogurt. The encapsulation improved the stability, solubility, and antioxidation activity of the astaxanthin and increased the extent of its potential industrial application. The encapsulated efficiency and solubility of the microencapsulated astaxanthin were 58.76% and 52.88%, respectively. In comparison with non-encapsulated astaxanthin, the microencapsulation did prevent the astaxanthin from dramatic degradation, with an astaxanthin retention value of 80.86% in the microencapsulated astaxanthin at 55 °C in 16 h. Non-encapsulated astaxanthin was much more stable in acid than in neutral phase, but the microencapsulated astaxanthin showed no significant difference in stability under both conditions. The astaxanthin yogurt showed an attractive orange-red color as well as a significantly higher DPPH-scavenging activity and stability than the plain yogurt.

A common mechanism explains the induction of aerobic fermentation and adaptive antioxidant response in Phaffia rhodozyma

BackgroundGrowth conditions that bring about stress on Phaffia rhodozyma cells encourage the synthesis of astaxanthin, an antioxidant carotenoid, which protects cells against oxidative damage. Using P. rhodozyma cultures performed with and without copper limitation, we examined the kinetics of astaxanthin synthesis along with the expression of asy, the key astaxanthin synthesis gene, as well as aox, which encodes an alternative oxidase protein.ResultsCopper deficiency had a detrimental effect on the rates of oxygen consumption and ethanol reassimilation at the diauxic shift. In contrast, copper deficiency prompted alcoholic fermentation under aerobic conditions and had a favorable effect on the astaxanthin content of cells, as well as on aox expression. Both cultures exhibited strong aox expression while consuming ethanol, but particularly when copper was absent.ConclusionWe show that the induction of either astaxanthin production, aox expression, or aerobic fermentation exemplifies the crucial role that redox imbalance plays in triggering any of these phenomena. Based on our own results and data from others, we propose a mechanism that rationalizes the central role played by changes of respiratory activity, which lead to redox imbalances, in triggering both the short-term antioxidant response as well as fermentation in yeasts and other cell types.

Biosynthesized silver and gold nanoparticles are potent antimycotics against opportunistic pathogenic yeasts and dermatophytes.

BackgroundEpidemiologic observations indicate that the number of systemic fungal infections has increased significantly during the past decades, however in human mycosis, mainly cutaneous infections predominate, generating major public health concerns and providing much of the impetus for current attempts to develop novel and efficient agents against cutaneous mycosis causing species. Innovative, environmentally benign and economic nanotechnology-based approaches have recently emerged utilizing principally biological sources to produce nano-sized structures with unique antimicrobial properties. In line with this, our aim was to generate silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) by biological synthesis and to study the effect of the obtained nanoparticles on cutaneous mycosis causing fungi and on human keratinocytes.MethodsCell-free extract of the red yeast Phaffia rhodozyma proved to be suitable for nanoparticle preparation and the generated AgNPs and AuNPs were characterized by transmission electron microscopy, dynamic light scattering and X-ray powder diffraction.ResultsAntifungal studies demonstrated that the biosynthesized silver particles were able to inhibit the growth of several opportunistic Candida or Cryptococcus species and were highly potent against filamentous Microsporum and Trichophyton dermatophytes. Among the tested species only Cryptococcus neoformans was susceptible to both AgNPs and AuNPs. Neither AgNPs nor AuNPs exerted toxicity on human keratinocytes.ConclusionOur results emphasize the therapeutic potential of such biosynthesized nanoparticles, since their biocompatibility to skin cells and their outstanding antifungal performance can be exploited for topical treatment and prophylaxis of superficial cutaneous mycosis.