145 research outputs found
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 Î 9âdesaturase and Î12âdesaturase 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
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 (<â44.4% by A. pullulans;â<â30.5% 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 ÎČ-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 âBy 2030, substantially reduce the number of deaths and illnesses from hazardous chemicals and air, water and soil pollution and contaminationâ (New York, September 2015). This studyâs 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
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
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 ÎČ-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
The relevance of fungi in astrobiology research â Astromycology
Since the very first steps of space exploration, fungi have been recorded as contaminants,
hitchhikers, or as part of missionsâ 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 astromycologyâs
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
Possible interactions between bacterial diversity, microbial activity and supraglacial hydrology of cryoconite holes in Svalbard
The diversity of highly active bacterial communities in cryoconite holes on three Arctic glaciers in Svalbard was investigated using terminal restriction fragment length polymorphism (T-RFLP) of the 16S rRNA locus. Construction and sequencing of clone libraries allowed several members of these communities to be identified, with Proteobacteria being the dominant one, followed by Cyanobacteria and Bacteroidetes. T-RFLP data revealed significantly different communities in holes on the (cold) valley glacier Austre BrĂžggerbreen relative to two adjacent (polythermal) valley glaciers, Midtre LovĂ©nbreen and Vestre BrĂžggerbreen. These population compositions correlate with differences in organic matter content, temperature and the metabolic activity of microbial communities concerned. No within-glacier spatial patterns were observed in the communities identified over the 2-year period and with the 1âkm-spaced sampling. We infer that surface hydrology is an important factor in the development of cryoconite bacterial communities
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