Fouling communities of microscopic fungi on various substrates of the Black Sea

Fungi are the most active biodeteriorators of natural and man-made materials. The article presents generalizations of the studies (2001–2019) of communities of microscopic fungi within biofilms on various substrates: shells of live Mytilus (Mytilus galloprovincialis, 670 specimens) and Ostreidae (Crassostrea gigas, 90 specimens), fragments of driftwood (over 7,000), stones (40), concrete of hydrotechnical constructions along the shoreline (80) and wood between concrete blocks in constructions on the shores (80). The studies were carried out in Odessa Oblast, the coastal zone of Sevastopol and open area of the Black Sea. There were identified 123 species of micromycetes, belonging to 65 genera, 33 families, 21 orders, 10 classes, 4 divisions, 2 kingdoms: Fungi and Chromista (fungi-like organisms). The Chromista kingdom was represented by 1 species – Ostracoblabe implexa, on shells of C. gigas. The number of species of micromycetes on various substrates varied 23 (wood between concrete blocks of hydrotechnical constructions) to 74 (shells of M. galloprovincialis at the depths of 3 and 6 m). On all the substrates, the following species were found; Alternaria alternata, Botryotrichum murorum. The communities were found to contain pathogenic fungi Aspergillus fumigatus (shells of mollusks, stones, concrete), A. terreus (concrete), Fusarium oxysporum, Pseudallescheria boydii (shells of mollusks). The best representation was seen for the Pleosporales order – from 12.9% (shells of M. galloprovincialis, 0.3 m depth) to 33.3% (shells of C. gigas) of the species composition. Toxin-producing species of Microascales in mycological communities accounted for 1.6% (driftwood) to 40.0% (concrete), and were also observed on shells of Bivalvia – 11.1–32.3%. Similarity of species composition of mycological communities according to Bray-Curtis coefficient varied 21.1% (driftwood and concrete, 10 shared species) to 72.7% (shells of M. galloprovincialis, the depths of 3 and 7 m and shells of C. gigas, 45 shared species). Using graphs of indices of mean taxonomic distinctness (AvTD, Δ+) and variation (Variation in Taxonomic Distinctness index, VarTD, Λ+), we determined deviations of taxonomic structure of the studied mycological communities from the level of mean expected values, calculated based on the list of species, taking into account their systematic positions. The lowest values of index Δ+ were determined for communities on shells of M. galloprovincialis, 0.3 m depth, driftwood, stones and concrete. These communities had uneven distribution of species according to higher taxonomic ranks and minimum number of the highest taxa: 4–6 classes, 1–2 divisions, Fungi kingdom. Disproportion in species composition with decrease in the number of the highest taxa occurred in extreme environmental conditions. Using index Λ+, we found that the most complex taxonomic structure of fungi communities has developed on concrete and shells of C. gigas. In mycological communities on those substrates, the number of species was low (25 and 46), but they belonged to 4–7 classes, 2–3 divisions, 1–2 kingdoms. To compare the structures of mycological communities that have developed in such substrates in biotopes sea, sea-land-air, land-air, we compiled a list of fungi based on the literature data, which, taking into account our data, comprised 445 species of 240 genera, 103 families, 51 orders, 15 classes, 5 divisions, 2 kingdoms. The analysis revealed that on substrates with similar chemical composition, in all the biotopes, the species of the same divisions dominated (genus and family may vary). Therefore, in the biotope land-air – Hypocreales, Pleosporales, Eurotiales (genera Acremonium, Fusarium, Alternaria, Aspergillus, Penicillium); sea – Pleosporales, Eurotiales, Microascales (Alternaria, Aspergillus, Penicillium, Corollospora); sea-land-air – Pleosporales, Microascales (Alternaria, Leptosphaeria, Aspergillus, Penicillium, Corollospora, Halosarpheia). Monitoring of species composition of myxomycetes is needed in farms that cultivate industrial objects, recreation sites, various buildings for prevention of mycotoxin intoxication and infestation by mycodermatoses and other diseases caused by opportunistic and pathogenic fungi.

Fungal keratitis caused by Pseudallescheria boydii: clinical and mycological characteristics

Background Pseudallescheria keratitis is rare but important type of fungal keratitis because of the inherently resistance of the organism to many existing antifungal agents. Methods Slit-lamp and confocal microscopy were used for clinical examinations. Fungal isolates were identified based on morphological characteristics and DNA sequence of the internal transcribed spacer region (ITS). In vitro antifungal susceptibility testing for fungal isolates was performed according to the Clinical and Laboratory Standards Institute (CLSI, M38-A2). Result All patients had a history of ocular trauma. In clinical examination hypopion were seen in three patients. The main antifungal medications were topical voriconazole. After treatment the visual acuity of all patients improved in 2–3 weeks. Conclusion All four patients of Pseudallescheria keratitis had similar clinical features. Accurate and rapid identification of species should be helpful in treating p. boydii keratitis.

In vivo efficacy of olorofim against systemic scedosporiosis and lomentosporiosis

Clinically relevant members of the Scedosporium / Pseudallescheria species complex and Lomentospora prolificans are generally resistant against currently available systemic antifungal agents in vitro and the infection due to these species is difficult to treat. We studied the in vivo efficacy of a new fungicidal agent olorofim (formerly F901318) against scedosporiosis and lomentosporiosis in neutropenic animals. Cyclophosphamide immunosuppressed CD-1 mice infected by Scedosporium apiospermum , Pseudallescheria boydii ( Scedosporium boydii ) and Lomentospora prolificans were treated by intraperitoneal administration of olorofim (15 mg/kg every 8 h for 9 days). The efficacy of olorofim treatment was assessed by the survival rate at 10 days post infection, levels of serum (1-3)-β-d-glucan (BG), histopathology, and fungal burden of kidneys 3 days post infection. Olorofim therapy significantly improved survival compared to the untreated controls; 80%, 100% and 100% of treated mice survived infection by Scedosporium apiospermum , Pseudallescheria boydii , and Lomentospora prolificans, respectively while less than 20% of the control mice (PBS-treated) survived at 10 days post infection. In the olorofim-treated neutropenic CD-1 mice infected with all three species, serum BG levels were significantly suppressed and fungal DNA detected in the target organs was significantly lower than controls. Furthermore, histopathology of kidneys revealed no or only few lesions with hyphal elements in the olorofim-treated mice, while numerous fungal hyphae were present in control mice. These results indicate olorofim to be a promising therapeutic agent for systemic scedosporiosis/lomentosporiosis, a devastating emerging fungal infection difficult to treat with currently available antifungals.

Biodegradation of Tetrahydrofuran by the Newly Isolated Filamentous Fungus Pseudallescheria boydii ZM01

Tetrahydrofuran (THF) is widely used as a precursor for polymer syntheses and a versatile solvent in industries. THF is an environmental hazard and carcinogenic to humans. In the present study, a new THF-degrading filamentous fungus, Pseudallescheria boydii ZM01, was isolated and characterized. Strain ZM01 can tolerate a maximum THF concentration of 260 mM and can completely degrade 5 mM THF in 48 h, with a maximum THF degradation rate of 133.40 mg THF h−1 g−1 dry weight. Growth inhibition was not observed when the initial THF concentration was below 150 mM, and the maximum THF degradation rate was still maintained at 118.21 mg THF h−1 g−1 dry weight at 50 mM THF, indicating the great potential of this strain to degrade THF at high concentrations. The initial key metabolic intermediate 2-hydroxytetrahydrofuran was detected and identified by gas chromatography (GC) analyses for the first time during the THF degradation process. Analyses of the effects of initial pH, incubation temperature, and heavy metal ions on THF degradation revealed that strain ZM01 can degrade THF under a relatively wide range of conditions and has good degradation ability under low pH and Cu2+ stress, suggesting its adaptability and applicability for industrial wastewater treatment.

1735. Epidemiology of Invasive Fungal Infections During Induction Chemotherapy in Adults With Newly Diagnosed Acute Myeloid Leukemia Without Antifungal Prophylaxis: A Retrospective Cohort Study

Background While invasive fungal infections (IFIs) are common in patients with acute myeloid leukemia (AML) undergoing induction chemotherapy, little current data exist on the epidemiology of IFIs in this patient population given widespread use of antifungal prophylaxis. Because our institution does not administer antifungal prophylaxis, we are in a unique position to study the natural history of IFIs in these patients. Methods We evaluated the incidence of IFIs using established definitions in adults with AML undergoing induction chemotherapy at Stanford Health Care from 2012 to 2017. We also analyzed incidence of antifungal treatment, impact of IFI diagnosis on survival, and risk factors for IFI development. Patients were followed for up to 12 weeks after beginning induction chemotherapy. Results Of 488 patients analyzed, 243 were eligible for inclusion. The median age was 57 (interquartile range 45–65). Men composed 134 (55%) of the patients and 157 (65%) where white. Fifty-four (22%) had antecedent myelodysplastic syndrome; most received a “7 + 3” regimen involving cytarabine and an anthracycline. Thirty-one (13%) developed a proven or probable IFI; 104 (43%) developed a proven, probable, or possible IFI. Most IFIs were due to lower respiratory tract disease. Eighteen identified organisms were Candida, including six C. albicans. Eight organisms were mold, including four Aspergillus isolates (all but one A. fumigatus) and one isolate each of Fusarium solani, Rhizomucor, Rhizopus, and Scedosporium apiospermum/Pseudallescheria boydii. One hundred ninety patients (78%) received antifungals during their initial admission and 99 (46%) of patients surviving their initial admission were discharged on antifungals. Only 66.7% of patients with a proven or probable IFI survived through 12 weeks, compared with 92.2% of those without (P = 0.007). Baseline absolute neutrophil count ≤500 cells/μL and longer duration of neutropenia were significantly associated with development of proven or probable IFIs. Conclusion Among patients receiving induction chemotherapy for AML, IFIs due to Candida and mold remain frequent absent antifungal prophylaxis and are associated with worse survival. Our findings support the use of antifungal prophylaxis in this patient population. Disclosures All authors: No reported disclosures.

Nest microbiota and pathogen abundance impact hatching success in sea turtle conservation

Hatchery practices are pivotal to conservation success. In sea turtle hatchery, reusing the same sand has been a norm but remains unclear whether such approach increases the risk of Fusarium solani species complex (FSSC) infection causing huge mortality in sea turtle eggs worldwide. We employed 16S and ITS amplicon sequencing in 123 sand samples and isolated fungal strains from diseased eggs across seven hatcheries and neighboring beaches in Malaysia. FSSC was isolated from all sampled hatcheries where F. solani/falciforme was the predominant species. A distinct microbial composition and higher abundance of FSSC (mean = 5.2 %) was found in all but one hatchery when compared to nesting beaches (mean = 1.3 %). Specifically, an ascomycetous fungus Pseudallescheria boydii consistently appeared in higher abundance (mean = 11.4 %) in FSSC-infected nests and was significantly associated with lower hatching success. The hatchery that maintained the most stringent practice by changing sand every nesting season had a microbiota resembling nesting beaches as well as lowest FSSC and P. boydii abundance. The results of current study imply the need to avoid reusing sand in sea turtle hatchery.

Structural Differences Influence Biological Properties of Glucosylceramides from Clinical and Environmental Isolates of Scedosporium aurantiacum and Pseudallescheria minutispora

Scedosporium/Lomentospora complex is composed of filamentous fungi, including some clinically relevant species, such as Pseudallescheria boydii, Scedosporium aurantiacum, and Scedosporium apiospermum. Glucosylceramide (GlcCer), a conserved neutral glycosphingolipid, has been described as an important cell surface molecule playing a role in fungal morphological transition and pathogenesis. The present work aimed at the evaluation of GlcCer structures in S. aurantiacum and Pseudallescheria minutispora, a clinical and an environmental isolate, respectively, in order to determine their participation in fungal growth and host-pathogen interactions. Structural analysis by positive ion-mode ESI-MS (electrospray ionization mass spectrometer) revealed the presence of different ceramide moieties in GlcCer in these species. Monoclonal antibodies against Aspergillus fumigatus GlcCer could recognize S. aurantiacum and P. minutispora conidia, suggesting a conserved epitope in fungal GlcCer. In addition, these antibodies reduced fungal viability, enhanced conidia phagocytosis by macrophages, and decreased fungal survival inside phagocytic cells. Purified GlcCer from both species led to macrophage activation, increasing cell viability as well as nitric oxide and superoxide production in different proportions between the two species. These results evidenced some important properties of GlcCer from species of the Scedosporium/Lomentospora complex, as well as the effects of monoclonal anti-GlcCer antibodies on fungal cells and host-pathogen interaction. The differences between the two species regarding the observed biological properties suggest that variation in GlcCer structures and strain origin could interfere in the role of GlcCer in host-pathogen interaction.