Abstract: The fungal strain M6-5 capable of producing aroma compounds was identified by morphology and molecular biology techniques (ITS sequence and tef1 sequence analysis), and the antifungal activity of volatile compounds from M6-5 at different growth stages against Alternaria alternata was tested. The volatile compounds were analyzed by headspace solid phase microextraction coupled with gas chromatography-tandem mass spectrometry (HPME-GC-MS). Antimicrobial properties of purified compounds were evaluated. A desiccator was used to analyze the inhibitory effect of volatile substances produced by strain M6-5 on postharvest black spot of Korla fragrant pear. The results showed that this strain was identified as Trichoderma erinaceum, and the antifungal activity of volatile substances produced by it against A. alternata reached a maximum on the fifth day of growth with an inhibition percentage of (82.48 ± 1.17)%, and was maintained until the 20th day. A total of 65 components were detected from strain M6-5 on the fifth day of growth, including 6-pentyl-2H-pyran-2-ketone, 3-hydroxybutyrate ethyl ester, phenylethanol, 2-allylfuran, and methyl palmitate, accounting for 40.12%, 6.49%, 4.38%, 4.13% and 3.48% of the total volatile substances, respectively. The inhibition percentages of 6-pentyl-2H-pyran-2-ketone, 3-hydroxy-ethyl butyrate and phenylethanol purified from a culture of strain M6-5 on A. alternata were (21.27 ± 0.60)%, (41.43 ± 2.36)% and (50.23 ± 1.07)%, respectively at a concentration of 714.28 μL/L. The volatile substances produced by strain M6-5 reduced the diameter of black spot in Korla fragrant pear by 42.46% compared with the control group. This study can provide useful information for the control of postharvest black spot in Korla fragrant pear.

Key words: aroma-producing fungus; identification; volatile substances; Alternaria alternata; Korla fragrant pear