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Applied and Environmental Microbiology Aug 2016Denitrifying fungi produce nitrous oxide (N2O), a potent greenhouse gas, as they generally lack the ability to convert N2O to dinitrogen. Contrary to the case for...
UNLABELLED
Denitrifying fungi produce nitrous oxide (N2O), a potent greenhouse gas, as they generally lack the ability to convert N2O to dinitrogen. Contrary to the case for bacterial denitrifiers, the prevalence and diversity of denitrifying fungi found in the environment are not well characterized. In this study, denitrifying fungi were isolated from various soil ecosystems, and novel PCR primers targeting the P450nor gene, encoding the enzyme responsible for the conversion of nitric oxide to N2O, were developed, validated, and used to study the diversity of cultivable fungal denitrifiers. This PCR assay was also used to detect P450nor genes directly from environmental soil samples. Fungal denitrification capabilities were further validated using an N2O gas detection assay and a PCR assay targeting the nirK gene. A collection of 492 facultative anaerobic fungi was isolated from 15 soil ecosystems and taxonomically identified by sequencing the internal transcribed spacer sequence. Twenty-seven fungal denitrifiers belonging to 10 genera had the P450nor and the nirK genes and produced N2O from nitrite. N2O production is reported in strains not commonly known as denitrifiers, such as Byssochlamys nivea, Volutella ciliata, Chloridium spp., and Trichocladium spp. The prevalence of fungal denitrifiers did not follow a soil ecosystem distribution; however, a higher diversity was observed in compost and agricultural soils. The phylogenetic trees constructed using partial P450nor and nirK gene sequences revealed that both genes clustered taxonomically closely related strains together.
IMPORTANCE
A PCR assay targeting the P450nor gene involved in fungal denitrification was developed and validated. The newly developed P450nor primers were used on fungal DNA extracted from a collection of fungi isolated from various soil environments and on DNA directly extracted from soil. The results indicated that approximatively 25% of all isolated fungi possessed this gene and were able to convert nitrite to N2O. All soil samples from which denitrifying fungi were isolated also tested positive for the presence of P450nor The P450nor gene detection assay was reliable in detecting a large diversity of fungal denitrifiers. Due to the lack of homology existing between P450nor and bacterial denitrification genes, it is expected that this assay will become a tool of choice for studying fungal denitrifiers.
Topics: Bacterial Proteins; Biodiversity; Denitrification; Fungi; Nitric Oxide; Nitrous Oxide; Phylogeny; Soil; Soil Microbiology
PubMed: 27208113
DOI: 10.1128/AEM.00231-16 -
Environmental Microbiology Feb 2015Ascospores of Neosartorya, Byssochlamys and Talaromyces can be regarded as the most stress-resistant eukaryotic cells. They can survive exposure at temperatures as high...
Ascospores of Neosartorya, Byssochlamys and Talaromyces can be regarded as the most stress-resistant eukaryotic cells. They can survive exposure at temperatures as high as 85°C for 100 min or more. Neosartorya fischeri ascospores are more viscous and more resistant to the combined stress of heat and desiccation than the ascospores of Talaromyces macrosporus which contain predominantly trehalose. These ascospores contain trehalose-based oligosaccharides (TOS) that are novel compatible solutes, which are accumulated to high levels. These compounds are also found in other members of the genus Neosartorya and in some other genera within the order Eurotiales that also include Byssochlamys and Talaromyces. The presence of oligosaccharides was observed in species that had a relatively high growth temperature. TOS glasses have a higher glass transition temperature (Tg ) than trehalose, and they form a stable glass with crystallizing molecules, such as mannitol. Our data indicate that TOS are important for prolonged stabilization of cells against stress. The possible unique role of these solutes in protection against dry heat conditions is discussed.
Topics: Dehydration; Food Microbiology; Hot Temperature; Neosartorya; Prevalence; Spores, Fungal; Stress, Physiological; Talaromyces; Temperature; Trehalose; Viscosity
PubMed: 25040129
DOI: 10.1111/1462-2920.12558 -
PloS One 2024Nematophagous fungi are the best alternatives to chemical nematicides for managing nematodes considering environmental health. In the current study, activity of...
Nematophagous fungi are the best alternatives to chemical nematicides for managing nematodes considering environmental health. In the current study, activity of metabolites from ten isolates of Purpureocillium lilacinum (Thom) Luangsa-ard (Hypocreales: Ophiocordycipitaceae) and two isolates of Paecilomyces variotii Bainier (Eurotiales: Trichocomaceae), were examined to inhibit the hatching of Meloidogyne incognita (Kofoid & White) Chitwood (Tylenchida: Heteroderidae) eggs. At 100%, 50%, and 25% concentrations, respectively, the culture filtrate of the isolate P. lilacinum 6887 prevented 97.55%, 90.52%, and 62.97% of egg hatching. Out of all the isolates, Pl 6887, Pl 6553, and Pl 2362 showed the greatest results in the hatching inhibition experiment.Gas chromatography-mass spectrometry (GC-MS) analysis revealed a variety of nematicidal compounds from different isolates. A total of seven nematicidal compounds, including four very potent nematicidal fatty acids were found in the isolate Pl 6553. Secondary metabolites of the same isolate possess the highest M. incognita juvenile mortality, i.e., 43.33% and 92% after 48 hrs of treatment at 100 and 200 ppm concentrations, respectively. Significant difference was observed in juvenile mortality percentage among the isolate having highest and lowest nematicidal compounds. Nematicidal fatty acids like myristic and lauric acid were found for the first time in P. lilacinum. Multiple vacuole-like droplets were found inside the unhatched eggs inoculated with the culture filtrate of isolate Pl 6887, and also in the juveniles that perished in the ethyl acetate extract of isolate Pl 6553.
Topics: Animals; Gas Chromatography-Mass Spectrometry; Hypocreales; Antinematodal Agents; Tylenchoidea; Fatty Acids; Byssochlamys
PubMed: 38358978
DOI: 10.1371/journal.pone.0297925 -
Genome Announcements Mar 2018sp. isolate BYSS01 (anamorph, sp.), which was isolated from jet fuel, is highly adapted to grow in hydrocarbons, having predicted genes involved in degradation of...
sp. isolate BYSS01 (anamorph, sp.), which was isolated from jet fuel, is highly adapted to grow in hydrocarbons, having predicted genes involved in degradation of -alkanes, branched alkanes, and aromatic compounds. The draft genome size is estimated at 29 Mb, containing 8,509 proteins.
PubMed: 29519843
DOI: 10.1128/genomeA.00164-18 -
Frontiers in Plant Science 2021Biochar has been reported to play a positive role in disease suppression against airborne pathogens in plants. The mechanisms behind this positive trait are not...
Biochar has been reported to play a positive role in disease suppression against airborne pathogens in plants. The mechanisms behind this positive trait are not well-understood. In this study, we hypothesized that the attraction of plant growth-promoting rhizobacteria (PGPR) or fungi (PGPF) underlies the mechanism of biochar in plant protection. The attraction of PGPR and PGPF may either activate the innate immune system of plants or help the plants with nutrient uptake. We studied the effect of biochar in peat substrate (PS) on the susceptibility of strawberry, both on leaves and fruits, against the airborne fungal pathogen . Biochar had a positive impact on the resistance of strawberry fruits but not the plant leaves. On leaves, the infection was more severe compared with plants without biochar in the PS. The different effects on fruits and plant leaves may indicate a trade-off between plant parts. Future studies should focus on monitoring gene expression and metabolites of strawberry fruits to investigate this potential trade-off effect. A change in the microbial community in the rhizosphere was also observed, with increased fungal diversity and higher abundances of amplicon sequence variants classified into , , and surrounding the plant root, where the latter two were reported as biocontrol agents. The change in the microbial community was not correlated with a change in nutrient uptake by the plant in either the leaves or the fruits. A decrease in the defense gene expression in the leaves was observed. In conclusion, the decreased infection of in strawberry fruits mediated by the addition of biochar in the PS is most likely regulated by the changes in the microbial community.
PubMed: 34497619
DOI: 10.3389/fpls.2021.700479 -
Journal of Microbiology and... Oct 2014A novel antifungal protein produced by the fungal strain Penicillium citrinum W1, which was isolated from a Southwest Indian Ocean sediment sample, was purified and...
A novel antifungal protein produced by the fungal strain Penicillium citrinum W1, which was isolated from a Southwest Indian Ocean sediment sample, was purified and characterized. The culture supernatant of P. citrinum W1 inhibited the mycelial growth of some plant pathogenic fungi. After saturation of P. citrinum W1 culture supernatants with ammonium sulfate and ion-exchange chromatography, an antifungal protein (PcPAF) was purified. The N-terminal amino acid sequence analysis showed that PcPAF might be an unknown antifungal protein. PcPAF displayed antifungal activity against Trichoderma viride, Fusarium oxysporum, Paecilomyces variotii, and Alternaria longipes at minimum inhibitory concentrations of 1.52, 6.08, 3.04, and 6.08 µg/disc, respectively. PcPAF possessed high thermostability and had a certain extent of protease and metal ion resistance. The results suggested that PcPAF may represent a novel antifungal protein with potential application in controlling plant pathogenic fungal infection.
Topics: Alternaria; Antifungal Agents; Byssochlamys; Drug Stability; Fungal Proteins; Hypocreales; Indian Ocean; Microbial Sensitivity Tests; Mycelium; Penicillium; Protein Stability; Seawater; Temperature
PubMed: 24931500
DOI: 10.4014/jmb.1405.05008 -
Irish Veterinary Journal 2014A three year old male entire Staffordshire bull terrier was referred to University College Dublin Veterinary Hospital, with a two week history of fever, inflammation of...
A three year old male entire Staffordshire bull terrier was referred to University College Dublin Veterinary Hospital, with a two week history of fever, inflammation of the right hock, lameness on the right hindlimb, peripheral lymphadenopathy and gastrointestinal signs (vomiting and diarrhoea). For the preceding three months the dog had been treated for atopic dermatitis with oral ciclosporin (5 mg/kg, PO, q 24 hours). Cytological analysis of the affected lymph nodes demonstrated fungal-like organisms predominantly contained within macrophages. Subsequent fungal culture and microscopic identification confirmed the presence of a Byssochlamys sp. This fungus is a saprophytic organism which has been associated with mycotoxin production. It has not previously been identified as a cause of systemic infection in animals or humans. Ciclosporin was discontinued, and a second generation triazole, voriconazole prescribed at a dose of 6 mg/kg for the first two doses, and continued at 3 mg/kg every 12 hours for six months. There was an excellent response. Follow-up examination five weeks after treatment was completed confirmed remission of the disease. The dog remains alive and well three years later. The present case represents an unusual fungal infection in a dog secondary to immunosuppressive therapy with ciclosporin. Such a possibility should be considered in animals presenting with signs consistent with systemic infection when receiving immunosuppressive medication.
PubMed: 25132957
DOI: 10.1186/2046-0481-67-17 -
Food Research International (Ottawa,... Nov 2020Contamination by spores is often the cause of fungal food spoilage. Some distinct strains of the food spoilage fungus Paecilomyces variotii are able to produce airborne...
Contamination by spores is often the cause of fungal food spoilage. Some distinct strains of the food spoilage fungus Paecilomyces variotii are able to produce airborne conidia that are more heat-resistant than similar species. These ellipsoid asexual spores can vary in size between strains, but also within strains. Here, we compared four measurement techniques to measure conidia size and distribution of five heat-sensitive and five heat-resistant P. variotii strains. Light microscopy (LM), Scanning Electron Microscopy (SEM) and Coulter Counter (CC) were used to measure and compare the spherical equivalent diameter, while CC and flow cytometry were used to study spore size distributions. The flow cytometry data was useful to study spore size distributions, but only relative spore sizes were obtained. There was no statistic difference between the method used of spore size measurement between LM, SEM and CC, but spore size was significantly different between strains with a 2.4-fold volume difference between the extremes. Various size distribution and shape parameters were correlated with conidial heat resistance. We found significant correlations in mean spore size, aspect ratio, roundness and skewness in relation to heat resistance, which suggests that these parameters are indicative for the conidial heat resistance of a P. variotii strain.
Topics: Byssochlamys; Food Microbiology; Hot Temperature; Paecilomyces; Spores, Fungal
PubMed: 33233149
DOI: 10.1016/j.foodres.2020.109514 -
Journal of Food Protection Oct 2015Heat-resistant fungal spores present a processing challenge for beverages and fruit juices, as thermal and UV strategies are often inadequate in reducing heat-resistant...
Heat-resistant fungal spores present a processing challenge for beverages and fruit juices, as thermal and UV strategies are often inadequate in reducing heat-resistant fungal burdens to acceptable levels. While effective against pathogenic or invasive bacteria, germicidal UV light treatments also fail to achieve an appreciable reduction of heat-resistant fungal spores. As an alternative, the efficacy of the antifungal protein YvgO was examined across a selection of fruit juices and teas, as well as solid model matrices. Compared with its efficacy in analogous liquid matrices, the apparent efficacy of YvgO was diminished on acidified solid matrices due to a reduction in YvgO diffusion. Using an XTT [2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] tetrazolium dye cytotoxicity assay, the effective concentrations to reduce growth by 50% were elucidated in samples challenged with Byssochlamys fulva H25. The MICs were determined and ranged from 2 ppm in apple juice and acidified teas to approximately 3 to 12 ppm for lemonade and orange, white cranberry, blueberry, prune, cherry, and grape juices. Apple cider and nonacidified teas showed reduced efficacy, with MICs exceeding 100 ppm. Tannin-rich products readily removed YvgO from the product, impairing its efficacy. Adding bovine serum albumin as a competitive inhibitor effectively reversed the YvgO-tannin association and restored efficacy in black but not green tea matrices. When challenged with a 5-log CFU inoculum of B. fulva, the shelf lives of the products were extended for various times up to 28 days in a concentrationdependent manner. However, initial efficacy was not predictive of shelf life extension, as some products exhibited improved protection at just two- and fourfold concentrations above the MIC, while others only exhibited long-term stability when concentrations exceeded 20 times the MIC. As such, YvgO may be an attractive alternative to currently available protection strategies and will provide needed diversity for natural food protectants.
Topics: Antifungal Agents; Byssochlamys; Electrophoresis, Polyacrylamide Gel; Food Contamination; Food Irradiation; Food Microbiology; Fruit; Fruit and Vegetable Juices; Hot Temperature; Hydrogen-Ion Concentration; Microbial Sensitivity Tests; Spores, Fungal; Tea; Ultraviolet Rays
PubMed: 26408134
DOI: 10.4315/0362-028X.JFP-15-128 -
The Plant Pathology Journal Oct 2018The red flour beetle, , is one of the most common and economically important pests of stored cereal products worldwide. Furthermore, these beetles can act as vectors for...
The red flour beetle, , is one of the most common and economically important pests of stored cereal products worldwide. Furthermore, these beetles can act as vectors for several fungal post-harvest diseases. In this study, we collected from 49 rice processing complexes (RPCs) nationwide during 2016-2017 and identified contaminating fungal species on the surface of the beetles. Five beetles from each region were placed on potato dextrose agar media or selection media after wet processing with 100% relative humidity at 27°C for one week. A total of 142 fungal isolates were thus collected. By sequence analysis of the internal transcribed spacer region, 23 fungal genera including one unidentified taxon were found to be associated with . The genus spp. (28.9%) was the most frequently present, followed by spp. (12.0%), (9.2%), spp. (8.5%), spp. (6.3%), spp. (5.6%), spp. (3.5%), (2.8%) and sp. (2.8%). Less commonly identified were genera , , , , , , , , , , , , , and . Among the isolates, two known mycotoxin-producing fungi, and spp. were also identified. This result is consistent with previous studies that surveyed fungal and mycotoxin contamination in rice from RPCs. Our study indicates that the storage pest, , would play an important role in spreading fungal contaminants and consequently increasing mycotoxin contamination in stored rice.
PubMed: 30369846
DOI: 10.5423/PPJ.OA.02.2018.0027