Analysis of SQR9 VCs
B. amyloliquefaciens SQR9 were grown in a head-space bottle containing MSgg medium for 6 d at 28 ℃. The head-space bottle was preheated in a 50 °C water bath for 5 minutes, then the VCs were collected with Solid-phase microextraction (SPME) fiber (50/30 μm DVB/CAR on PDMS) for 30min. The SPME fiber was removed and desorbed at 180 °C for 4 minutes. Gas chromatography-mass spectrometry (GC-MS) analysis was carried out by Agilent 7890A-5975V, equipped with a chromatographic column (Agilent DB-wax, 30m×0.25mm×0.25µm). Helium was used as the carrier gas (1 ml/min), and the injection temperature was 260 °C. The column was held at 40 °C for 5 min and then programmed to increase by 5 °C per min to a final temperature of 250 °C, which was maintained for 5 min. The interface temperature, ion source temperature and quadrupole temperature was 260 °C, 230 °C and 150 °C respectively; the ionization mode was EI+, 70ev; the detector voltage was 1106V; the scanning mode was full-scan, and the mass range is 20-400. These compounds were identified by comparison with mass spectra from a library of NIST 2011 through Agilent MSD ChemStation (E.02.00.493).