Mycology最新文献

The search for a novel microbial producer of cellulases including a glucose tolerant β-glucosidase is a challenge as most are inhibited by their product glucose. This study aims to screen for cellulolytic fungi using qualitative and quantitative screening methods. Primary screening revealed 34 of 46 fungal isolates with β-glucosidase activity. Eleven and 13 of these also displayed endoglucanase and exoglucanase activities, respectively. During secondary screening, this number was reduced to 26 β-glucosidase producers with 13 also having endoglucanase and exoglucanase activities. Isolate C1 displayed enhanced production of β-glucosidases in the presence of 0.05 M glucose (69% higher activity). Optimisation of growth conditions for β-glucosidase production by one variable at a time experiments improved production for (isolates) PS1 (64%), MB5 (84%), and C2 (69%). Isolate PS1 identified as Chaetomella sp. BBA70074 displayed the highest tolerance to glucose, retaining 10% of β-glucosidase activity in the presence of 0.8 M glucose. Tolerance to glucose increased to 14% when produced under optimal conditions. β-Glucosidase had a molecular weight of 170 kDa with a pH and temperature optima of 6 and 70°C, respectively. Future studies will include optimisation of the production of the glucose tolerant enzyme by Chaetomella sp. BBA70074.

Candida albicans and its related species can cause opportunistic infections such as "candidiasis" in immunocompromised individuals with a high morbidity and mortality rate. Several antifungal drugs available in the market are often used to treat infections caused by pathogenic fungi. However, in fungi, the development of resistance against these drugs quickly evolved. Candida is a dimorphic fungus that can switch between yeast to hyphae form, requires an active biosynthesis of membrane constituents. Sphingolipid and ergosterol molecules, are the major fungal plasma membrane components, and their interaction with the antifungal drug can modulate drug susceptibility. A lipophilic compound farnesol acts as a quorum-sensing molecule synthesised by the isoprenoid biosynthesis pathway in the fungal pathogen Candida. Farnesol is secreted in a cell density-dependent manner inhibits hyphae germination and biofilm formation. In this study, we have investigated whether the farnesol molecules affect the drug susceptibility of the antifungal drug Amphotericin B (AmB) which mainly binds with ergosterol, and Aureobasidin A (AbA), a complex sphingolipid biosynthesis inhibitor. Our studies revealed that a non-toxic and low concentration of farnesol can reduce the efficacy of AmB and AbA on yeast cells. This reduction is probably through the alteration in the complex sphingolipid biosynthesis and ATP-binding cassette (ABC) type membrane transport activity. These findings may shed light on a new direction to explore the role of lipid molecules in the antifungal drug resistance mechanisms in pathogenic yeast.

Fungal contamination in water-damaged houses has become a major concern because of their potential health effects. During our survey in 100 water-damaged houses in southern California, we have reported 42 outdoor and 14 indoor fungal species throughout the year. Six commonly occurring indoor fungal species are Alternaria alternata, Aspergillus niger, Chaetomium globosum, Cladosporium herbarum, Penicillium chrysogenum and Stachybotrys chartarum. In the damp building materials, S. chartarum was found to be associated with A. niger, C. globosum and P. chrysogenum but not with A. alternata and C. herbarum. Stachybotrys chartarum showed strong antagonistic effect against A. alternata and C. herbarum and significantly inhibited in vitro growth of A. alternata and C. herbarum but had no effect on A. niger, C. globosum and P. chrysogenum. Two trichothecenes, produced by Stachybotrys sp., trichodermin and trichodermol, significantly inhibited spore germination and in vitro growth of A. alternata and C. herbarum but had no effect on A. niger, C. globosum, P. chrysogenum and S. chartarum. In the damp building materials (drywall, ceiling tile, and oak wood), S. chartarum significantly inhibited the growth of A. alternata and C. herbarum and had no effect on A. niger, C. globosum and P. chrysogenum in these substrata.

Species of Gyroporus from southern China were studied in this study. Based on morphology and molecular phylogenetic analyses of DNA sequences from the nuclear ribosomal internal transcribed spacer (ITS), the nuclear ribosomal large subunit (nrLSU), and the mitochondrial adenosine triphosphate ATP synthase subunit 6 (atp6), Gyroporus was divided into four main branches in the phylogenetic tree, and four sections were firstly proposed i.e. Gyroporus sect. Castaneus, G. sect. Cyanescens, G. sect. Longicystidiatus and G. sect. Pallidus. Five new species, i.e. G. alboluteus, G. atrocyanescens, G. pseudolongicystidiatus, G. pallidus and G. subcaerulescens, were revealed from China, and their phylogenetic positions were also analysed. Among them, G. alboluteus and G. pallidus were nested into the sect. Pallidus, although morphologically similar to G. castaneus; G. atrocyanescens and G. subcaerulescens, with obvious cyanescent oxidation reactions, were nested into the sect. Cyanescens; and G. pseudolongicystidiatus characterised by its long cystidia and was nested into the sect. Longicystidiatus. The new species were formally described and illustrated in the present study, and a key to the sections and species of Gyroporus in China was provided.

[This corrects the article DOI: 10.1080/21501203.2020.1816584.].

Fungi are renowned for their ability to produce extracellular enzymes into their surrounding environment. Xylanases are hydrolytic enzymes capable of xylan degradation. The objectives of this study were to isolate, screen for potential xylanolytic fungi from soil and tree bark samples from three locations in South Africa and to determine their growth conditions for maximum xylanase production. Forty-six isolates were obtained based on clearing zone formation on xylan-enriched agar plates using Congo red indicator. Xylanase activity was quantified during submerged fermentation. Isolate MS5, identified as Trichoderma harzianum with the highest enzyme activity (38.17 U/ml) was selected for further studies based on thermophilic properties (70°C) and pH (5.0). The culture conditions; incubation period (5 days), agitation speed (160 rpm) wheat bran (1%) and ammonium sulphate (1.2%) were optimised further. Biochemical characterisation of the crude enzyme revealed two pH and temperature optima (pH 6.0 at 60°C and 70°C, pH 8.0 at 55°C and 75°C). The enzyme retained >70% activity after 4 h at pH 6.0 at 70°C. SDS-PAGE revealed multiple protein bands with a prominent band at 70 kDa. Substrate Native PAGE revealed multiple isoforms between 55 and 130 kDa. This enzyme will be beneficial for applications in the animal feed and biofuels industries.

In recent years, the scientific names of many cultivated and well-known medicinal fungal species have been changed. However, the results of taxonomic and nomenclature works on these economically important fungi are often overlooked or ignored in applied researches. The incorrect use of scientific names may cause uncertainty in research and in the global medicinal mushroom market. In this paper, we briefly review the current taxonomy and nomenclature of "Fuling" medicinal mushroom and make a proposal for biochemists, pharmacists and businessmen on the correct use of scientific names related to this species. Based on the recent taxonomic results and nomenclatural proposals, the use of the names Wolfiporia extensa, W. cocos and especially Poria cocos for the "Fuling" mushroom are incorrect and misleading; therefore, the acceptance of the names Pachyma hoelen or Wolfiporia hoelen is recommended.

Polysaccharides in boletes (Boletales) are economically significant to both function food and medicinal industries. The polysaccharides were extracted from the fruit bodies of eight boletes, namely, Aureoboletus longicollis, Butyriboletus hainanensis, Crocinoboletus rufoaureus, Hemioporus japonicus, Neoboletus infuscatus, Neoboletus obscureumbrinus, Tylopilus otsuensis, Xanthoconium fusciceps, which were collected from tropical China; their physicochemical properties and antioxidant activities were characterised and evaluated, respectively. The results revealed that the polysaccharides among the eight boletes were mainly composed of glucose, mannose, and galactose, with a broad molecular weight range, and contained a pyranose ring revealed by FT-IR and NMR spectral analyses. Many factors such as different species of boletes, geographic conditions, molecular weight, configuration, and monosaccharide content may affect the antioxidant power of polysaccharides, simultaneously, instead of one single factor. The antioxidant activities of the polysaccharides were measured according to in vitro assays of DPPH scavenging, superoxide anion scavenging, and ferrous ion reducing tests. The polysaccharide of C. rufoaureus has greatly superior antioxidant activity and it could serve as potential functional food or medicine.

Four dimeric diketopiperazine stereoisomers (1-4) including two new ones (1-2) had been isolated from the culture broth of one marine-derived fungus Aspergillus sp. Z3, which was found in the gut of a marine isopod Ligia exotica. The planner structures and absolute configurations of the new compounds were determined by combination of NMR, HRESIMS, electronic circular dichroism calculation, Marfey's method as well as single-crystal X-ray diffraction. Their cytotoxicity against the prostate cancer PC3 cell line was assayed by the MTT method.