Bacterial Volatile Organic Compounds Analysis

ST-TJ4 strain was inoculated into 250 mL Erlenmeyer flask containing 100 mL of liquid KB medium at a rate of 1% and cultured at 28 °C, 180 rpm for 60 h. To avoid the escape of VOCs, the conical flask was sealed with aluminium foil. Uninoculated KB medium was performed as the control. A 65 μm PDMS/DVB fiber tip was selected for the determination of bacterial VOCs, and the extraction tip was first aged when used for the first time [16 (link)]. The aging temperature of the extraction head selected in this experiment was 250 °C, and the time was 30 min. The cultured bacteria sample was shaken and placed in a 40 °C water bath. The needle of the SPME was inserted through the tin foil and extracted for 30 min. The fiber head was inserted into the gasification chamber of the gas chromatograph (Agilent 7000B, Santa Clara, CA, USA). The sample was analyzed at high temperature in the gasification chamber for 3 min.
GC-MS conditions: using Rtx–5 quartz capillary column; He as the carrier gas; 230 °C as the inlet temperature; 40 °C as the initial temperature, keep it for 3 min, increase temperature at 10 °C/min to 95 °C, and then raise temperature at 30 °C/min to 230 °C. Keep 230 °C for 5 min, ion source is EI source; electron energy is 70 eV; spectrum search is searched by Nist 05 and Nist 05 s library [16 (link)].