Total Ergosterol Research Articles

Behaviour of Saccharomyces cerevisiae wine strains during adaptation to unfavourable conditions of fermentation on synthetic medium: Cell lipid composition, membrane integrity, viability and fermentative activity

During must fermentation wine strains are exposed to a variety of biotic and abiotic stresses which, when prevailing over the cellular defence systems, can affect cell viability with negative consequences on the progression of the fermentative process. To investigate the ability of wine strains to survive and adapt to unfavourable conditions of fermentation, the lipid composition, membrane integrity, cell viability and fermentative activity of three strains of Saccharomyces cerevisiae were analysed during hypoxic growth in a sugar-rich medium lacking lipid nutrients. These are stressful conditions, not unusual during must fermentation, which, by affecting lipid biosynthesis may exert a negative effect on yeast viability. The results obtained showed that the three strains were able to modulate cell lipid composition during fermentation. However, only two of them, which showed highest viability and membrane integrity at the end of the fermentation process, reached a fatty acid composition which seemed to be optimal for a successful adaptation. In particular, C16/TFA and UFA/TFA ratios, more than total lipid and ergosterol contents, seem to be involved in yeast adaptation.

Hydrophilic Fungi and Ergosterol Associated with Respiratory Illness in a Water-Damaged Building

BackgroundDamp building–related respiratory illnesses are an important public health issue.ObjectiveWe compared three respiratory case groups defined by questionnaire responses [200 respiratory cases, 123 of the respiratory cases who met the epidemiologic asthma definition, and 49 of the epidemiologic asthma cases who had current physician-diagnosed asthma with post-occupancy onset] to a comparison group of 152 asymptomatic employees in an office building with a history of water damage.MethodsWe analyzed dust samples collected from floors and chairs of 323 cases and comparisons for culturable fungi, ergosterol, endotoxin, and cat and dog allergens. We examined associations of total fungi, hydrophilic fungi (requiring water activity ≥ 0.9), and ergosterol with the health outcomes using logistic regression models.ResultsIn models adjusted for demographics, respiratory illnesses showed significant linear exposure–response relationships to total culturable fungi [interquartile range odds ratios (IQR-OR) = 1.37–1.72], hydrophilic fungi (IQR-OR = 1.45–2.19), and ergosterol (IQR-OR = 1.54–1.60) in floor and chair dusts. Of three outcomes analyzed, current asthma with postoccupancy physician diagnosis was most strongly associated with exposure to hydrophilic fungi in models adjusted for ergosterol, endotoxin, and demographics (IQR-OR = 2.09 for floor and 1.79 for chair dusts). Ergosterol levels in floor dust were significantly associated with epidemiologic asthma independent of culturable fungi (IQR-OR = 1.54–1.55).ConclusionsOur findings extend the 2004 conclusions of the Institute of Medicine [Human health effects associated with damp indoor environments. In: Damp Indoor Spaces and Health. Washington DC:National Academies Press, 183–269] by showing that mold levels in dust were associated with new-onset asthma in this damp indoor environment. Hydrophilic fungi and ergosterol as measures of fungal biomass may have promise as markers of risk of building-related respiratory diseases in damp indoor environments.

Distribution of free and esterified ergosterols in the medicinal fungus Ganoderma lucidum

The fruiting bodies, spores, and lipid from the spores of Ganoderma lucidum have been widely used for medicinal purpose in China. Ergosterol content may be a suitable marker for evaluating the quality of ganoderma spore and ganoderma spore lipid (GSL) products. A gradient reversed-phase high-performance liquid chromatography method was developed for the simultaneous determination of free and esterified ergosterols in G. lucidum. The contents of free and esterified ergosterols in the different parts (the stipe, pileus, tubes, and spores) of G. lucidum and GSL were determined. The results showed that total ergosterol levels in the stipe, pileus, tubes, and spores of G. lucidum were between 0.8 and 1.6 mg/g. The relative abundances of free to esterified ergosterol were different in the different parts of G. lucidum. The spores and the tubes, the hymenophore tissue that contains the spore-producing cells, have a considerably higher percentage of ergosteryl esters (41.9 and 39.7% of total ergosterol) in comparison with the pileus and stipe tissues (3.6 and 6.2%).

Preliminary survey of indoor and outdoor airborne microfungi at coastal buildings in Egypt

Forty six species and two sterile fungi and yeast species were isolated from samples collected both indoors and outdoors of coastal buildings located in an Egyptian coastal city. Twenty flats from ten buildings were investigated; children living in these buildings have been reported to suffer from respiratory illnesses. Samples were taken using a New Brunswick sampler (model STA-101) operating for 3.0 min at a flow rate of 6.0 l/min. Most of the species isolated have been associated with symptoms of respiratory allergies. Indoors the total culturable fungal count was 1548 CFU/m3; outdoors, it was 1452 CFU/m3. Indoor values of culturable fungal count, total spores count and ergosterol content ranged from 52 to 124 CFU/m3, 100 to 400 spore/m3 and 5 to 27.7 mg/m3, respectively, whereas outdoor levels typically varied between 25 and 222 CFU/m3, 110 and 900 spore/m3 and 3.3 and 67.2 mg/m3, respectively. The maxima for these parameters were detected indoors in house no. 6 and outdoors, outside of house no. 7. The most abundant species were primarily mitosporic (2832 CFU/m3). The most frequent species in both the indoor and outdoor samples were Cladosporium cladosporioides followed by Alternaria alternata and Penicillium chrysogenum,with inside:outside ratios of 1.4, 1.8 and 1.9, respectively. The patterns of fungal abundance were influenced to some extent by changes in the relative humidity and temperature. Other factors, such as type of culture media, rate of sedimentation, size, survival rates of spore and species competition,also affected fungal counts and should be taken into consideration during any analysis of bioaerosol data.

Detection of Fusarium sp. contamination in corn by enzyme-linked immunosorbent assay

Fusarium verticillioides is a primary corn pathogen and one of the main producers of fumonisins, a group of mycotoxins that cause several diseases in animals and probably also affect humans. An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) based on polyclonal antibodies was developed to detect the exoantigen of this fungus in corn and its correlation with traditional methods for mould detection was evaluated. Forty freshly harvested corn samples were analysed for F. verticillioides exoantigens, as well as for total mould count, ergosterol and fumonisin levels in order to evaluate the relationship between these parameters. In addition, F. verticillioides was grown in brain heart infusion (BHI) broth in order to evaluate the correlation between biomass and exoantigen concentration. There was no significant correlation between exoantigen concentration and total mould count, Fusarium sp. count and fumonisin levels. The correlation coefficient between exoantigens and ergosterol content was 0.52 and between biomass and F. verticillioides exoantigens in BHI broth was 0.84. These results suggest that this ic-ELISA has potential for Fusarium sp. detection in corn samples.

Effect of nitrogen limitation on the ergosterol production by fed-batch culture of Saccharomyces cerevisiae

The diversity and content of available nitrogen sources in the growth medium both are very important in the accumulation of ergosterol in the yeast cell membrane. Growth on the good nitrogen sources such as ammonia can harvest more yeast cells than on poor ones, but ergosterol content in those yeast cells is relatively lower. Ergosterol content, one of the most variable parameters in ergosterol production by yeast cultivation, is greatly influenced by nitrogen limitation. The aim of our work was to study how the nitrogen sources affected the membrane ergosterol content and increase the total ergosterol yield. On the premise of keeping high ergosterol content in yeast cell, the ergosterol yield was enhanced by increasing the yeast biomass. Direct feed back control of glucose using an on-line ethanol concentration monitor was introduced to achieve high cell density. Ammonia, which acted as nitrogen source, was added to adjust pH during fermentation process, but its addition needed careful control. Cultivation in 5 L bioreactor was carried out under following conditions: culture temperature 30 ± 1 °C, pH 5.5 ± 0.1, agitation speed 600 rpm, controlling ethanol concentration bellow 1% and controlling ammonium ion concentration bellow 0.1 mol/L. Under these conditions the yeast dry weight reached 95.0 ± 2.6 g/L and the ergosterol yield reached 1981 ± 34 mg/L.

Ergosterol as a biomarker for the quantification of the fungal biomass in atmospheric aerosols

The prevailing warm and humid climate in subtropical cities favors fungal growth in the ambient environment. Fungal growth has implications for public health because fungal cells, spores and their metabolites are allergenic and potential health hazards. In this regard, better and quicker alternatives than the available sampling and species identification methods are needed for quantifying fungal communities in atmospheric aerosols. In this study, the fungal membrane ergosterol was used as a biomarker for assessing the abundance and mass loading of fungi in atmospheric aerosols. Gas chromatography-mass spectrometry (GC-MS) was utilized for quantification of this biomarker in fine (PM 2.5) and coarse (PM 2.5–10) particulates collected by high volume samplers simultaneously at a rural site and an urban site in Hong Kong. The geometric means of the total ergosterol concentrations at the rural and urban sites were 120.2 and 93.9 pg m −3 in the PM 10 (calculated as the sum of PM 2.5 and PM 2.5–10) particulates. The significantly higher ergosterol loading at the rural site was related to the vegetation coverage around the sampling site. Ergosterol loading was higher in the autumn at both sites, which correlated with seasonal drops in the relative humidity below 70%. Approximately 65–66% of the ergosterol in PM 10 is associated with fine particulates, indicating that atmospheric fungi likely lead to chronic respiratory symptoms. The mass loading of the fungal spores on the dry mass was on the order of 10–10 2 ng m −3. The geometric mean concentration of the fungal spores was estimated as 46 and 36 spores m −3, which was one-sixth of the measured viable samplings of 292 and 247 CFU m −3 at the rural and urban sites, respectively. This underestimation leads to the need for establishing proper conversion factors from conditions identical to or simulating the study system of interest when markers are quantified and estimated for microbial mass loading in ambient aerosols. This study was the first to utilize the fungal biomarker ergosterol in monitoring and assessing ambient fungal loading and prevalence in atmospheric aerosols for a period of eight months. It confirms that biomarkers can provide quantitative information on microbial communities in atmospheric aerosols.

Effects of environmental factors and leaf chemistry on leaf litter colonization by fungi in a Mediterranean shrubland

Estimation of litter colonization by fungi, using ergosterol, an indicator of fungal biomass, is a reliable way to describe the process of leaf litter decomposition. This litter colonization by fungi is regulated both by exogenous or environmental factors, and endogenous factors, i.e. litter chemistry. In this work, we have examined the effects of some of these factors on litter fungal colonization in a Mediterranean ecosystem, by determining ergosterol content of Quercus coccifera leaf litter. Environmental factors have been studied through the fertility of the soil, by comparing plots amended with two rates of compost and plots without amendment. Results indicated that (i) compost had a significant effect on soil fertility but did not increase ergosterol content of leaf litter and (ii) soil humidity improved leaf litter colonization by fungi. Endogenous factors have been studied through measurements of total phenolic and ergosterol concentrations of seven shrub species leaf litter. We have shown (i) a negative significant correlation between total phenolic compounds and ergosterol concentrations of leaf litter and (ii) a positive significant correlation between total phenolic compound concentrations in green leaves and in leaf litter. We conclude that, in this Mediterranean shrub ecosystem, leaf litter colonization by fungi is controlled by soil moisture and plant leaf litter quality.

Functional Analysis of Ca IPT1 , a Sphingolipid Biosynthetic Gene Involved in Multidrug Resistance and Morphogenesis of Candida albicans

In the present study we describe the isolation and functional analysis of a sphingolipid biosynthetic gene, IPT1, of Candida albicans. The functional consequence of the disruption of both alleles of IPT1 was confirmed by mass analysis of its sphingolipid composition. The disruption of both alleles or a single allele of IPT1 did not lead to any change in growth phenotype or total sphingolipid, ergosterol, or phospholipid content of the mutant cells. The loss of mannosyl diinositol diphosphoceramide [M(IP)(2)C] in the ipt1 disruptant, however, resulted in increased sensitivity to drugs like 4-nitroquinoline oxide, terbinafine, o-phenanthroline, fluconazole, itraconazole, and ketoconazole. The increase in drug susceptibilities of ipt1 cells was linked to an altered sphingolipid composition, which appeared to be due to the impaired functionality of Cdr1p, a major drug efflux pump of C. albicans that belongs to the ATP binding cassette superfamily. Our confocal and Western blotting results demonstrated that surface localization of green fluorescent protein-tagged Cdr1p was affected in ipt1 disruptant cells. Poor surface localization of Cdr1p resulted in an impaired ability to efflux fluconazole and rhodamine 6G. The effect of mannosyl inositol phosphoceramide accumulation in the ipt1 mutant and the absence of M(IP)(2)C from the ipt1 mutant on the efflux of drug substrates was very selective. The efflux of methotrexate, a specific substrate of CaMdr1p, another major efflux pump of major facilitator superfamily, remained unaffected in ipt1 mutant cells. Interestingly, changes in sphingolipid composition affected the ability of mutant cells to form proper hyphae in various media. Taken together, our results demonstrate that an altered composition of sphingolipid, which is among the major constituents of membrane rafts, affects the drug susceptibilities and morphogenesis of C. albicans.

Correlation of total ergosterol levels in stored canola with fungal deterioration

Deterioration of canola caused by fungal growth during storage is a problem at moisture contents exceeding 8%. Secondary indicators of fungal growth, such as ergosterol, the main sterol found in fungal cell membranes, offer a way of relating fungal biomass to deterioration. The objective of this research was to determine ergosterol accumulation in stored canola and to correlate it with seed deterioration measured by germination, fungal infection, fat acidity values (FAV), and carbon dioxide production. Total ergosterol levels increased with storage time, temperature, and seed moisture content. Aggressive and destructive fungal species such as Aspergillus candidus and Penicillium spp. contributed more to ergosterol than Eurotium spp. Initial total ergosterol concentrations between 1.46 and 1.67 ppm may be taken as the background levels in sound canola, and levels greater than 2 ppm were related to significant levels of spoilage. Results showed that germination and FAV had a strong correlation with total ergosterol (Spearman rank order correlation coefficients of −0.826 and 0.800, respectively) but the relationship was weaker for CO 2 production (Spearman rank order correlation coefficient of 0.650).

Effects of Culture Conditions on Ergosterol Biosynthesis bySaccharomyces cerevisiae

Ergosterol is an essential component of yeast cells that maintains the integrity of the membrane. It was investigated as an important factor in the ethanol tolerance of yeast cells. We investigated the effects of brewing conditions on the ergosterol contents of S. cerevisiae K-9, sake yeast, several kinds of Saccharomyces cerevisiae that produce more than 20% ethanol, and X2180-1A, laboratory yeast. K-9 had a higher total ergosterol contents under all the conditions we examined than X2180-1A. Ethanol and hypoxia were found to have negative and synergistic effects on the total ergosterol contents of both strains, and significantly reduced the free ergosterol contents of X2180-1A but only slightly reduced those of K-9. The maintenance of free ergosterol contents under brewing conditions might be an important character of sake yeast strains. DNA microarray analysis also showed higher expression of ergosterol biosynthesis genes in K-9 than in X2180-1A.

Comparison of methods for the assessment of growth of food spoilage moulds in solid substrates

The objective of the study was to evaluate the general suitability of ergosterol content, CFU, and colony diameters determinations for a range of fungi representing food spoilage moulds for the assessment of their growth on solid substrates, in particular intermediate moisture foods. Sixteen food-borne mould species were inoculated onto DG18 agar overlaid with cellophane, allowing determination of a direct measurement of biomass density weighing. The samples were also evaluated with regard to visible and microscopic colony diameters, total ergosterol content, Thoma counts, viable CFU counts, and so on. The same parameters were assayed in the spore suspensions obtained from those cultures. Data were evaluated by multivariate data analysis using projection methods such as principal component analysis (PCA), showing some groupings among the measured variables, mainly linked to the sporulating/nonsporulating nature of the different species tested. Ratios among the different variables were obtained, compared among the species, and evaluated along time (2–10 days). It was concluded that, as a general rule for all the species, ergosterol content and colony diameters were better correlated to fungal biomass dry weight than CFU counts were. Conversion factors were 0.3–3 μg ergosterol mg −1 biomass dry weight and 76–227 mg biomass dry weight cm −2, depending on the species.

Ergosterol production by fed-batch fermentation of Saccharomyces cerevisiae

The parameters in the cultivation of ergosterol were studied. The relationship between biomass, ergosterol content of Saccharomyces cerevisiae and parameters such as dissolved oxygen (DO), oxygen uptake rate (OUR), pH, glucose concentration were discussed. The constant feed rate fed-batch, constant glucose-concentration fed-batch, exponential fed-batch, DO-control exponential fed-batch, pulse fed-batch and DO-control pulse fed-batch are used to optimize the ergosterol fermentation. It was found that DO could serve as an effective control parameter for yeast fed-batch fermentation. When the DO was kept at 12% (±1%) and pulse fed-batch was used, the total ergosterol yield could be enhanced to 1160 mg/l.

Mouldy houses influence symptoms of asthma among atopic individuals.

The influence of current levels of indoor fungi on asthma is a controversial issue that needs to be resolved in order to advise patients appropriately. To assess the seasonal variation in indoor fungal levels and the impact of these levels on asthma among mould-sensitized individuals. Thirty-five young adults with current asthma and sensitization to fungi were visited four times over 1 year. At each home visit a questionnaire was administered and samples of dust and air were collected. Participants also recorded information on symptoms, peak expiratory flows (PEF) and medication use. Dust samples were analysed for house dust mite allergen (Der p 1) and total fungal biomass (ergosterol). Total and genus-specific fungal propagules were identified in air samples. Seasonal variation in allergen levels and significant independent effects of fungal levels on peak flow variability (PFV) were identified by repeated measures analysis of variance. Significant seasonal variations were observed in viable airborne fungi, ergosterol levels in the floor dust and PFV. PFV correlated significantly with symptom scores and the dose of reliever medication. PFV was also significantly associated with smoking and visible mould. The association between visible mould and PFV was independent of season, smoking and the dose of reliever medication. However, there was no association between total fungi, specific fungi or ergosterol and PFV. Der p 1 levels had no significant influence on asthma, even in HDM-sensitized individuals. Mouldy homes adversely influence asthma in asthmatics sensitized to fungi.

Evaluation of transcript level and biomass during mycelial development of the truffle, Tuber borchii

The growth of the truffle, Tuber borchii, mycelial strain (1BO) was analysed using biomolecular methods. Total RNA evaluation and ergosterol assay revealed that transcriptional and metabolic activity reach a peak at around 30–50 days of growth and decrease by 70 days. mRNA electrophoretic profiles highlighted a very low degree of variation in gene expression during the growth of mycelium.

Determinination of soil fungal biomass from soil ergosterol analyses

Determination of fungal biomass (FB) and FB-carbon (FB-C) from soil ergosterol concentration is difficult because of unknown ergosterol-to-fungal biomass (E-to-FB) conversion factors and inefficient ergosterol extraction methods. We applied a microwave-assisted extraction (MAE) and high performance liquid chromatographic (HPLC) procedure to measure ergosterol in soil samples. The E-to-FB conversion factors were determined in six species of fungi grown in vitro. The MAE method was fast and extracted up to nine times more soil ergosterol than a classical refluxing saponification method. Soil ergosterol was separated and quantified rapidly (<10 min) by HPLC. Alternaria alternata, Chaetomium globosum, Fusarium oxysporum, Penicillum chrysogenum, Rhizopus stolonifer and Trichoderma harzianum isolated from soil and plant matrices were grown in batch. Ergosterol and biomass content were determined in mycelia harvested during the stationary and exponential phases of growth. Total mycelial ergosterol ranged from 180 to 2178 μg, and total dry biomass ranged from 17 to 595 mg. Total ergosterol and fungal dry biomass were strongly associated ( r 2 = 0.95). The C content in mycelial mats averaged 43% (±1.1, SD), and was similar among fungal species and growth phases. The analyses of variance showed that the E-to-FB ratio was similar among fungal species or growth phase. An average ergosterol concentration of 4 μg mg −1 dry biomass was determined for the six species of fungi, which gave a conversion factor of 250 μg dry biomass μg −1 ergosterol. The MAE method recovered an average of 62% (±11%, SD) of the ergosterol added in mycelial mats to soils prior to extraction, and its recovery was independent of soil properties. The E-to-FB ratio and percent recovery of mycelial ergosterol helped establish for the first time relationships determining soil FB and FB-C from soil ergosterol concentration. The amount of FB ranged from 155 to 4745 μg g −1 and that for FB-C ranged from 67 to 2040 μg g −1 for different soils, and was higher in samples taken from native undisturbed land than in samples taken from adjacent cultivated fields. Measurement of soil ergosterol concentration is a useful estimate content of the living soil FB.

Ergosterol and microbial biomass in the rhizosphere of grassland soils

Fungal and microbial biomass were determined by ergosterol and fumigation–extraction, respectively, in bulk grassland soil (<2 mm), rhizosphere and root material. The aim was to quantify the contribution of these three microbial fractions to the total soil microbial biomass and to soil organic matter. In the bulk soil, the average concentration was 3.37 μg g −1 for ergosterol, 860 μg g −1 for microbial biomass C, and 30.4 mg g −1 for organic C. In the rhizosphere material, the corresponding concentrations exceeded those of the bulk soil by 80, 80 and 50%, respectively. The large average ergosterol concentration of 74.2 mg g −1 root revealed a strong fungal colonisation of the root material. About 75% of the total ergosterol was found in the bulk soil fraction, 11% in the rhizosphere and 14% in the root material. In one soil nearly half of total ergosterol was found in the root material. However, the average ergosterol-to-biomass ratio in the root material was less than a third of the bulk soil or the rhizosphere soil, indicating that approximately two-thirds of CHCl 3-labile C are presumably root-derived.

Resistance of Venturia inaequalis to the sterol biosynthesis-inhibiting fungicide, penconazole [1-(2-(2,4-dichlorophenyl) pentyl)-1H-1,2,4-triazole

The likelihood of development of penconazole resistance in Venturia inaequalis was demonstrated using chemical mutagenesis of a wild isolate of the pathogen not previously exposed to penconazole. Mutant strains displayed a high degree of resistance which was stable. There was significant variation in the rate of total lipid and ergosterol biosyntheses between the resistant and sensitive strains. Low uptake of penconazole due to energy-dependent efflux was found to be the mechanism underlying penconazole resistance in the mutant strains, which also exhibited negatively correlated cross-resistance to mancozeb.

Lichen respiration in relation to active time, temperature, nitrogen and ergosterol concentrations

1. Respiration in eight lichen species was related to thallus hydration status, external temperature and to total nitrogen, chitin and ergosterol concentrations. Chitin is a nitrogenous and major compound of the fungal cell wall, and ergosterol is a sterol of the plasma membrane in fungi and sometimes in algae. 2. Hydration of previously dry thalli resulted in an initially high rate of respiration. Both the amplitude of this resaturation respiration and the time required to reach steady state varied among species. Generally, peak rates were one to three times higher than steady‐state rates, which were reached 3–7 h after hydration. 3. Increases in external temperature also resulted in transient bursts in respiration. Again, both the amplitude of the burst and the time required to reach steady state varied among species. Also depending on species, a temperature increase from 5 to 15 °C resulted in two‐ to fivefold increases in steady‐state respiration. 4. Steady‐state respiration, at optimal thallus hydration and a given temperature, varied three‐ to sixfold among the species, when related to thallus dry mass. This difference correlated best (r2 = 0·89) with their ergosterol concentration, where a doubling in ergosterol resulted in more than a doubling in respiration. Respiration correlated less well to total nitrogen or chitin. 5. The chitin to ergosterol ratio varied more than one order of magnitude between the species, where species with high nitrogen concentrations had the highest ratio. This implies that species with access to ample amounts of nitrogen can make more fungal cell walls in relation to plasma membrane surface area.

Relationships among deoxynivalenol, ergosterol and Fusarium exoantigens in Canadian hard and soft wheat

Soluble extracellular components (exoantigens) from cultures of Fusarium graminearum and F. sporotrichioides were used to produce antisera from chickens for an indirect enzyme immunoassay. This immunoassay was used to estimate Fusarium exoantigen levels in 40 samples of fusarium head blight-infected hard red spring wheat from Manitoba, and in 50 samples of infected soft white winter wheat from Ontario. These wheat samples were also assayed for deoxynivalenol (DON), the predominant Fusarium mycotoxin, and for ergosterol, a metabolite reflecting fungal biomass. Using F. sporotrichioides antisera, the linear correlations between exoantigen level and DON content for the hard and soft wheats had coefficients of 0.80 and 0.76, respectively. With the same antisera, linear correlations between exoantigen level and total ergosterol concentration for the hard and soft wheats had coefficients of 0.66 and 0.81, respectively.