M. hyalina produces the sulfur-containing volatile tris(methylthio)methane (TMTM)
To identify the volatiles from M. hyalina which are responsible for the garlic-like smell, the GC-MS chromatograms of SPME volatile collections of the headspace of slant cultures of M. hyalina were compared with the collections from the headspace of the growth medium. Three major constituents could be identified (Figure 1) of which the HR-MS of the molecular ions M+ and [M+2]+ (for the 34S isotopologue) revealed the molecular formulas C3H8S2 (m/z measured 108.0062, 110.0020 calc. 108.0062, 110.0020; RI 894; 2% rel.), C3H8S3 (m/z measured 137.9626, 139.9585 calc. 137.9626, 139.9584; RI 1197; 2% rel.), and C4H10S3 (m/z measured 153.9942, 155.9910 calc. 153.9939, 155.9897, RI 1217; 96% rel.). C3H8S2 and C3H8S3 could be identified as bis(methylthio)methane (RIlit. 889) and dimethyl trithiocarbonate (RIlit. 1196), respectively by comparison of their mass spectra and RI with the datasets of the NIST library and additionally with mass spectra and RI of authentic samples recorded under the same conditions.
For C4H10S3, the major compound of the headspace of M. hyalina , library searches in NIST and Wiley mass spectra databases revealed no hit in combination with the RI. Therefore M. hyalina was extracted by hydro distillation. The obtained essential oil consisted mainly of three compounds (by GC-MS): Octenol-3-ol (22.4%) 3-octenone (21.7%) and C4H10S3 (27,3%). NMR analysis of the mixture could reduce the structure motive of C4H10S3 to (CH3-X)n-CH (X = S, O, etc. ) which in combination with the empirical formula C4H10S3 from HR-MS led to the structure of tris(thiomethyl)methane. Comparison with an authentic sample of tris(methylthio)methane (Aldrich) showed to be identical with respect to NMR and mass spectra, and RI (Figure 1 and Table 1).