Identification of Volatile Sulfur Compounds Produced by Schizophyllum commune

Abstract

Schizophyllum commune is a causative agent of allergic bronchopulmonary mycosis, allergic fungal rhinosinusitis, and basidiomycosis. Diagnosis of these diseases remains difficult because no commercially available tool exists to identify the pathogen. Unique volatile organic compounds produced by a pathogen might be useful for non-invasive diagnosis. Here, we explored microbial volatile organic compounds produced by S. commune. Volatile sulfur compounds, dimethyl disulfide (48 of 49 strains) and methyl ethyl disulfide (49 of 49 strains), diethyl disulfide (34 of 49 strains), dimethyl trisulfide (40 of 49 strains), and dimethyl tetrasulfide (32 of 49 strains) were detected from headspace air in S. commune cultured vials. Every S. commune strain produced at least one volatile sulfur compound analyzed in this study. Those volatile sulfur compounds were not detected from the cultures of Aspergillus spp. (A. fumigatus, A. flavus, A. niger, and A. terreus), which are other major causative agents of allergic bronchopulmonary mycosis. The last, we examined H₂S detection using lead acetate paper. Headspace air from S. commune rapidly turned the lead acetate paper black. These results suggest that those volatile sulfur compounds are potent targets for the diagnosis of S. commune and infectious diseases.

Keywords: Schizophyllum commune; allergic bronchopulmonary mycosis; microbial volatile organic compounds; volatile sulfur compounds.

Figure 1

Major polysulfides produced by S. commune IFM 59347, a representative strain in which five polysulfides were detected: dimethyl disulfide (DMDS), methyl ethyl disulfide (MEDS), diethyl disulfide (DEDS), dimethyl trisulfide (DMTriS), and dimethyl tetrasulfide (DMTetraS). They are shown in the total ion chromatogram (a) and each extracted-ion chromatogram (b).

Figure 2

Plots of peak areas of each polysulfide and their respective coefficients of determination. The x-axis and y-axis in each plot are shown respectively in the top row and the right column.

Figure 3

Extracted-ion chromatograms of VOCs from A. fumigatus IFM 51748. The gray-shaded area shows the putative retention time of each polysulfide.

Figure 4

Detection of H₂S using lead acetate paper. Lead acetate paper appearance exposed in a non-inoculated plate (left) and to VOCs from S. commune IFM 54713 (middle) and A. fumigatus IFM 51941 (right) for three days under 35 °C.

Figure 5

Detection of H₂S using lead acetate paper. The whiteness of lead acetate.