Expression of fatty-acid-modifying enzymes in the halotolerant black yeast Aureobasidium pullulans (de Bary) G. Arnaud under salt stress

AbstractMultiple tolerance to stressful environmental conditions of the black, yeast-like fungus Aureobasidium pullulans is achieved through different adaptations, among which there is the restructuring of the lipid composition of their membranes. Here, we describe three novel genes encoding fatty-acid-modifying enzymes in A. pullulans, along with the levels of their mRNAs under different salinity conditions. High levels of Δ 9−desaturase and Δ12−desaturase mRNAs were seen at high salinities, which were consistent with an increased desaturation of the fatty acids in the cell membranes. Elevated levels of elongase mRNA were also detected. Surprisingly, increases in the levels of these mRNAs were also seen following hypo-osmotic shock, while hyperosmotic shock had exactly the opposite effect, demonstrating that data that are obtained from up-shift and down-shift salinity studies should be interpreted with caution

HMG-CoA reductase is regulated by environmental salinity and its activity is essential for halotolerance in halophilic fungi

The activity and level of HMG-CoA reductase (HMGR) were addressed in halophilic fungi isolated from solar saltpans. Representative fungi belonging to the orders Dothideales, Eurotiales and Wallemiales have a specific pattern of HMGR regulation, which differs from salt-sensitive and moderately salt-tolerant yeasts. In all of the halophilic fungi studied, HMGR amounts and activities were the lowest at optimal growth salinity and increased under hyposaline and hypersaline conditions. This profile paralleled isoprenylation of cellular proteins in H. werneckii. Inhibition of HMGR in vivo by lovastatin impaired the halotolerant character. HMGR may thus serve as an important molecular marker of halotolerance

Bioactivity of volatile organic compounds by Aureobasidium species against gray mold of tomato and table grape

Aureobasidium strains isolated from diverse unconventional environments belonging to the species A. pullulans, A. melanogenum, and A. subglaciale were evaluated for Volatile Organic Compounds (VOCs) production as a part of their modes of action against Botrytis cinerea of tomato and table grape. By in vitro assay, VOCs generated by the antagonists belonging to the species A. subglaciale showed the highest inhibition percentage of the pathogen mycelial growth (65.4%). In vivo tests were conducted with tomatoes and grapes artificially inoculated with B. cinerea conidial suspension, and exposed to VOCs emitted by the most efficient antagonists of each species (AP1, AM10, AS14) showing that VOCs of AP1 (A. pullulans) reduced the incidence by 67%, partially confirmed by the in vitro results. Conversely, on table grape, VOCs produced by all the strains did not control the fungal incidence but were only reducing the infection severity (< 44.4% by A. pullulans; < 30.5% by A. melanogenum, and A. subglaciale). Solid-phase microextraction (SPME) and subsequent gas chromatography coupled to mass spectrometry identified ethanol, 3-methyl-1-butanol, 2-methyl-1-propanol as the most produced VOCs. However, there were differences in the amounts of produced VOCs as well as in their repertoire. The EC50 values of VOCs for reduction of mycelial growth of B. cinerea uncovered 3-methyl-1-butanol as the most effective compound. The study demonstrated that the production and the efficacy of VOCs by Aureobasidium could be directly related to the specific species and pathosystem and uncovers new possibilities for searching more efficient VOCs producing strains in unconventional habitats other than plant

Redefinition of Aureobasidium pullulans and its varieties

Using media with low water activity, a large numbers of aureobasidium-like black yeasts were isolated from glacial and subglacial ice of three polythermal glaciers from the coastal Arctic environment of Kongsfjorden (Svalbard, Spitsbergen), as well as from adjacent sea water, sea ice and glacial meltwaters. To characterise the genetic variability of Aureobasidium pullulans strains originating from the Arctic and strains originating pan-globally, a multilocus molecular analysis was performed, through rDNA (internal transcribed spacers, partial 28 S rDNA), and partial introns and exons of genes encoding β-tubulin (TUB), translation elongation factor (EF1α) and elongase (ELO). Two globally ubiquitous varieties were distinguished: var. pullulans, occurring particularly in slightly osmotic substrates and in the phyllosphere; and var. melanogenum, mainly isolated from watery habitats. Both varieties were commonly isolated from the sampled Arctic habitats. However, some aureobasidium-like strains from subglacial ice from three different glaciers in Kongsfjorden (Svalbard, Spitsbergen), appeared to represent a new variety of A. pullulans. A strain from dolomitic marble in Namibia was found to belong to yet another variety. No molecular support has as yet been found for the previously described var. aubasidani. A partial elongase-encoding gene was successfully used as a phylogenetic marker at the (infra-)specific level

Fungal contaminants: a paradoxal void in safety regulation of drinking water and recreational areas

Objectives: The United Nations sustainable development goal #3, aims to “By 2030, substantially reduce the number of deaths and illnesses from hazardous chemicals and air, water and soil pollution and contamination” (New York, September 2015). This study’s objective is to assess the European drinking and bathing water regulations and detect missing fungal parameters that may affect human health.info:eu-repo/semantics/publishedVersio

Adaptation of extremely halotolerant black yeast Hortaea werneckii to increased osmolarity: a molecular perspective at a glance

Halophilic adaptations have been studied almost exclusively on prokaryotic microorganisms. Discovery of the black yeast Hortaea werneckii as the dominant fungal species in hypersaline waters enabled the introduction of a new model organism to study the mechanisms of salt tolerance in eukaryotes. Its strategies of cellular osmotic adaptations on the physiological and molecular level revealed novel, intricate mechanisms to combat fluctuating salinity. H. werneckii is an extremely halotolerant eukaryotic microorganism and thus a promising source of transgenes for osmotolerance improvement of industrially important yeasts, as well as in crops

Phylogeny and ecology of the ubiquitous saprobe Cladosporium sphaerospermum, with descriptions of seven new species from hypersaline environments

Saprobic Cladosporium isolates morphologically similar to C. sphaerospermum are phylogenetically analysed on the basis of DNA sequences of the ribosomal RNA gene cluster, including the internal transcribed spacer regions ITS1 and ITS2, the 5.8S rDNA (ITS) and the small subunit (SSU) rDNA as well as β-tubulin and actin gene introns and exons. Most of the C. sphaerospermum-like species show halotolerance as a recurrent feature. Cladosporium sphaerospermum, which is characterised by almost globose conidia, is redefined on the basis of its ex-neotype culture. Cladosporium dominicanum, C. psychrotolerans, C. velox, C. spinulosum and C. halotolerans, all with globoid conidia, are newly described on the basis of phylogenetic analyses and cryptic morphological and physiological characters. Cladosporium halotolerans was isolated from hypersaline water and bathrooms and detected once on dolphin skin. Cladosporium dominicanum and C. velox were isolated from plant material and hypersaline water. Cladosporium psychrotolerans, which grows well at 4 °C but not at 30 °C, and C. spinulosum, having conspicuously ornamented conidia with long digitate projections, are currently only known from hypersaline water. We also newly describe C. salinae from hypersaline water and C. fusiforme from hypersaline water and animal feed. Both species have ovoid to ellipsoid conidia and are therefore reminiscent of C. herbarum. Cladosporium langeronii (= Hormodendrum langeronii) previously described as a pathogen on human skin, is halotolerant but has not yet been recorded from hypersaline environments

Antihyperlipidemic effects of Pleurotus ostreatus (oyster mushrooms) in HIV-infected individuals taking antiretroviral therapy

<p>Abstract</p> <p>Background</p> <p>Antiretroviral treatment (ART) regimens in HIV patients commonly cause significant lipid elevations, including increases in both triglycerides and cholesterol. Standard treatments for hypercholesterolemia include the HMG CoA reductase inhibitors, or "statins." Because many ART agents and statins share a common metabolic pathway that uses the cytochrome P450 enzyme system, coadministration of ART with statins could increase statin plasma levels significantly. The oyster mushroom, <it>Pleurotus ostreatus</it>, has been shown in animal models to decrease lipid levels - a finding that has been supported by preliminary data in a small human trial.</p> <p>Methods</p> <p>To assess the safety and efficacy of <it>P. ostreatus </it>in patients with HIV and ART-induced hyperlipidemia, a single-arm, open-label, proof-of-concept study of 8 weeks' duration with a target enrollment of 20 subjects was conducted. Study patients with ART-induced elevated non-HDL cholesterol levels (> 160 mg/dL) were enrolled. Participants received packets of freeze-dried <it>P. ostreatus </it>(15 gm/day) to be administered orally for the 8 week trial period. Lipid levels were drawn every two weeks to assess efficacy. Safety assessments included self-reported incidence of muscle aches and measurement of liver and muscle enzymes. Mean within-person change in lipid levels were estimated using generalized estimating equations to account for repeated observations on individuals. A 30 mg/dL decrease in non-HDL cholesterol was deemed clinically significant.</p> <p>Results</p> <p>126 patients were screened to enroll 25, of which 20 completed the 8-week study. The mean age was 46.4 years (36-60). Patients had a mean 13.7 yrs of HIV infection. Mean non-HDL cholesterol was 204.5 mg/dL at day 0 and 200.2 mg/dL at day 56 (mean within-person change = -1.70; 95% confidence interval (CI) = -17.4, 14.0). HDL cholesterol levels increased from 37.8 mg/dL at day 0 to 40.4 mg/dL on day 56 (mean within-person change = 2.6; 95% CI = -0.1, 5.2). Triglycerides dropped from 336.4 mg/dL on day 0 to 273.4 mg/dL on day 56 (mean within-person change = -63.0; 95% CI = -120.9, -5.1). Only 3 individuals achieved a sustained clinically significant (30 mg/dL) decline in non-HDL cholesterol after 8 weeks of therapy. There were no adverse experiences reported other than patients' distaste for the preparation. Liver function tests and muscle enzymes were not affected by the 8 weeks of treatment.</p> <p>Conclusions</p> <p><it>Pleurotus ostreatus </it>as administered in this experiment did not lower non-HDL cholesterol in HIV patients with ART-induced hypercholesterolemia. Small changes in HDL and triglycerides were not of a clinical magnitude to warrant further study.</p> <p>Trial Registration</p> <p>clinicaltrials.gov Identifier: <a href="http://www.clinicaltrials.gov/ct2/show/NCT00069524">NCT00069524</a></p

The relevance of fungi in astrobiology research – Astromycology

Since the very first steps of space exploration, fungi have been recorded as contaminants, hitchhikers, or as part of missions’ crews and payloads. Because fungi can cause human disease and are highly active decomposers, their presence in a space-linked context has been a source of major concern given their possible detrimental effects on crews and space structures. However, fungi can also be beneficial and be used for many space applications. The exact effects on fungi are not always clear as they possess high adaptability and plasticity, and their phenotypes and genotypes can undergo several changes under the extreme conditions found in space, thus leading to different results than those we would have on Earth. Understanding and analysing these aspects is the subject of astromycology, a research field within astrobiology. The impending situation of a resurgent space race is expected to boost astromycology’s visibility and importance. However, researchers lack both a framework and a solid base of knowledge from which to contextualise their work. This critical review addresses this gap by conceptualising the field of astromycology, covering key research and current questions pertaining to the field, and providing a relevant research instrument for future work