Determination of volatile organic compounds released by Trichoderma species and plant endophytic fungi using a needle-type extraction device and gas chromatography-mass spectrometry

This study proposes a method for the extraction of volatile organic compounds (VOCs) generated by Trichoderma species and plant endophytic fungi. In this method, generated VOCs are extracted using a needle-type extraction device and analyzed using gas chromatography-mass spectrometry. To extract VOCs generated by a single cultured fungi species, each fungi species was cultivated in a sealed 100 mL polypropylene bottle. Before cultivation, two silicone septa were attached to the bottle and cap. After the preparation of the culture media in the bottle, the bottle was autoclaved and the fungi were inoculated. The bottle was then sealed with a cap, and the air in the bottle was replaced with clean air. The surfaces of the extraction needle and a gas supply needle were sterilized with ethanol and inserted into the bottle via the two silicone septa. A gas sampling bag filled with pure air was connected to the gas supply needle, and clean air was continuously supplied to the bottle as the purge gas during the gas sampling. As the extraction needle, a double-bed-type adsorbent, Carbopack-X and a carbon molecular sieve, was used 3-Methyl butanol and 2-methyl butanol were detected for 41 species, and 2-pentylfran and 6-pentyl-2-pyrone were detected for 2 species among the 46 considered Trichoderma species. Monoterpenes and sesquiterpenes were detected for a single plant endophytic fungus species. The limit of detection of standard 3-methyl butanol and 2-methyl butanol in the proposed method was 0.5 ng mL-1. The performance of the proposed method was compared with that of the commercial MonoTrap method.