The present study focuses on the inhibitory effect of volatile metabolites released by Bacillus velezensis CT32 on Verticillium dahliae and Fusarium oxysporum, the causal agents of strawberry vascular wilt. The CT32 strain was isolated from maize straw compost tea and identified as B. velezensis based on 16S rRNA gene sequence analysis. Bioassays conducted in sealed plates revealed that the volatile organic compounds (VOCs) produced by the strain CT32 possessed broad-spectrum antifungal activity against eight phytopathogenic fungi. The volatile profile of strain CT32 was obtained by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). A total of 30 volatile compounds were identified, six of which have not previously been detected in bacteria or fungi: (Z)-5-undecene, decyl formate, 2,4-dimethyl-6-tert-butylphenol, dodecanenitrile, 2-methylpentadecane and 2,2’,5,5’-tetramethyl-1,1’-biphenyl. Pure compounds were tested in vitro for their inhibitory effect on the mycelial growth of V. dahliae and F. oxysporum. Decanal, benzothiazole, 3-undecanone, 2-undecanone, 2-undecanol, undecanal and 2,4-dimethyl-6-tert-butylphenol showed high antifungal activity, with benzothiazole and 2,4-dimethyl-6-tert-butylphenol being the most potent compounds. These results indicate that the VOCs produced by B. velezensis CT32 have the potential to be used as a biofumigant for management of vascular wilt pathogens.

Aroma components from the ripe fruit of Prunus salicina L. cv. Friar and their changes during cold storage were analyzed in this study. Fifty-one volatiles were identified by dichloromethane direct extraction method using gas chromatography–mass spectrophotometry (GC-MS). Their total content was 50.4 μg/g, including alcohols, aldehydes, esters, lactones, acids, ketones, phenols, and small amounts of hydrocarbons and heterocyclic compounds. Nine compounds were determined as the would-be impact odorants of Prunus salicina L. cv. Friar, accounting for 24.7% of contents of total aroma components. According to the size of the aroma indices, their contribution to the aroma was list: (E)-2-hexenal, γ-dodecalactone, hexyl acetate, butane-2,3-diol, 3-methyl-2-butene-1-ol, hexanal, butyl acetate, 1-butanol, and 2-methyl-1-butanol. Compared with the ripe fruit of Prunus salicina L. cv. Friar, types and relative contents of the would-be impact odorants declined during cold storage at 0^°C and the shelf-life period at 20°C after harvest. This result showed that low temperature inhibited the synthesis of aroma components to a certain extent. The lack of acetates and lactones, which contributed to fruit aroma largely, was the main reason for fading of fruit flavor after cold storage.

A newly developed descriptor, three-dimensional holographic vector of atomic interaction field (3D-HoVAIF), was used to describe the chemical structures of purine bases. After variable screening by stepwise multiple regression (SMR) technique, a partial least square (PLS) regression model was built with 3D-HoVAIF. The model was satisfactory comparing to reference since correlation coefficients of molecular modeling (R _cum ² ), cross-validation (Q _cum ² ) and standard deviation of estimation (SD) were 0.966, 0.860 and 0.112, respectively, showing that the model had favorable estimation and prediction capabilities. It was illustrated that information related to retention data of purine bases could preferably be expressed by 3D-HoVAIF with definite physico-chemical meanings and easy structural interpretation for purine bases. It was illustrated that 3D-HoVAIF was to preferably express retention data of purine bases and had definite physicochemical significance. So 3D-HoVAIF was a useful structural expression technique for quantitative structure activity (or property or retention) relationships (QSAR/QSPR/QSRR) study, such as structural characterization and chromatographic retention prediction.