Volatile Organic Compounds Produced by sp. Strain R2 Inhibit Growth In Vitro and in Unhulled Rice.

Volatile organic compounds (VOCs) produced by species exhibit biocontrol activity against fungal pathogens of fruits and vegetables. However, research on the effect of VOCs on in stored grains is limited. This study aimed to investigate the effects of VOCs extracted from the strain R2, which was isolated from unhulled rice and identified as on in vitro and unhulled rice. R2 VOCs effectively inhibited conidial germination and the hyphal growth of in vitro. Moreover, R2 VOCs reduced the fungal population, aflatoxin B (AFB) levels, and free fatty acid (FFA) value by 90.8%, 67%, and 38.7%, respectively, in unhulled rice. Eighteen R2 VOCs were identified using headspace solid-phase micro-extraction gas chromatography-mass spectrometry, and the individual activity of the VOCs against was tested in vitro. Benzaldehyde (Ben) and 3,7-dimethyl-1-octanol (Dmo) showed strong inhibitory activities against on PDA plates, with inhibition rates of 100% and 91.2%, respectively, at a concentration of 20 μL/dish. Ben at the concentration of 0.09 mg/mL, Dmo at the concentration of 0.07 mg/mL, or a mixture of both at halved concentrations could reduce the fungal population, AFB levels, and FFA content in unhulled rice. Our findings suggest that R2 VOCs are good alternatives to traditional chemical fumigants for suppressing in stored grains. However, further research is necessary to establish the optimal fumigation concentration of these two components in unhulled rice. The impact of their residues on grain quality should be explored through sensory evaluation and nutritional analysis, and their safety to the environment and human body should be evaluated through safety assessment.