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Screening Mold Colonies by Using Two Toxicity Assays Revealed Indoor Strains of Aspergillus calidoustus Producing Ophiobolins G and K

1
Department of Civil Engineering, Aalto University, Box 12100, FI-00076 Aalto, Finland
2
Department of Microbiology, Faculty of Science and Informatics, University of Szeged, Közép fasor 52, 6727 Szeged, Hungary
3
Department of Civil Engineering and Architecture, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia
*
Author to whom correspondence should be addressed.
Toxins 2019, 11(12), 683; https://doi.org/10.3390/toxins11120683
Received: 26 August 2019 / Revised: 14 November 2019 / Accepted: 19 November 2019 / Published: 21 November 2019
(This article belongs to the Section Mycotoxins)
The occurrence and toxin production of the opportunistic pathogen Aspergillus calidoustus in Finnish buildings is not well documented in the literature. We tracked and identified four A. calidoustus colonies cultivated from indoor settled dusts and revealed the biological activities of crude biomass extracts. The toxic substances were identified as 6-epi-ophiobolin K, ophiobolin K, and ophiobolin G by high-performance liquid chromatography–mass spectrometry (HPLC-MS) based on chromatographic and mass spectrometry data (MS and MS/MS) on the crude extract of A. calidoustus strain MH34. A total of 29 fungal colonies collected from settled dust in an office room reported for indoor-air-related illnesses were screened for toxins that inhibited boar sperm motility in the BSMI (boar sperm motility inhibiting) assay and cell proliferation in the ICP (inhibition of cell proliferation) assays with PK-15 cells. Out of the 27 colonies tested as toxic, 12 colonies exhibiting conidiophores representative of the genera Chaetomium, Penicillium, and Paecilomyces were excluded from the study, while 13 colonies exhibited Aspergillus-like conidiophores. Biomass suspensions of these colonies were divided into two categories: Category 1 colonies (n = 4), toxic in the BSMI assay and the ICP assays, emitted blue fluorescence and grew at 37 °C; Category 2 colonies (n = 9), only toxic in the ICP assay, emitted orange fluorescence and exhibited limited or no growth at 37 °C. Colonies in Category 1 were pure-cultured, and the strains were named as MH4, MH21, MH34, MH36. Strain MH34 was identified as A. calidoustus by the internal transcribed spacer (ITS) sequences. Ethanol-soluble dry substances extracted from the biomass of the pure cultures exhibited a toxicological profile in the BSMI assay, SMID (sperm membrane integrity damage) assay, and ICP assay similar to that exhibited by pure ophiobolin A. Overall, the viable conidia of A. calidoustus in indoor settled dusts deserve attention when potentially hazardous mold species are monitored. View Full-Text
Keywords: Aspergillus calidoustus; ophiobolins; indoor mold; fluorescence Aspergillus calidoustus; ophiobolins; indoor mold; fluorescence
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MDPI and ACS Style

Salo, M.J.; Marik, T.; Bencsik, O.; Mikkola, R.; Kredics, L.; Szekeres, A.; Andersson, M.A.; Salonen, H.; Kurnitski, J. Screening Mold Colonies by Using Two Toxicity Assays Revealed Indoor Strains of Aspergillus calidoustus Producing Ophiobolins G and K. Toxins 2019, 11, 683. https://doi.org/10.3390/toxins11120683

AMA Style

Salo MJ, Marik T, Bencsik O, Mikkola R, Kredics L, Szekeres A, Andersson MA, Salonen H, Kurnitski J. Screening Mold Colonies by Using Two Toxicity Assays Revealed Indoor Strains of Aspergillus calidoustus Producing Ophiobolins G and K. Toxins. 2019; 11(12):683. https://doi.org/10.3390/toxins11120683

Chicago/Turabian Style

Salo, Marja Johanna, Tamás Marik, Ottó Bencsik, Raimo Mikkola, László Kredics, András Szekeres, Maria A. Andersson, Heidi Salonen, and Jarek Kurnitski. 2019. "Screening Mold Colonies by Using Two Toxicity Assays Revealed Indoor Strains of Aspergillus calidoustus Producing Ophiobolins G and K" Toxins 11, no. 12: 683. https://doi.org/10.3390/toxins11120683

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