2.6.2. DMSP Consumption

Two hundred microlitres of QS bacterial suspension in seawater (OD_600nm = 0.3) was mixed with 1.8 mL DMSP medium (0.6 mmol/L DMSP, 4 mmol/L NH₄Cl, 30 nmol/L NaH₂PO₄, 100 nmol/L EDTA-Fe, 100 nmol/L ZnCl₂, 100 nmol/L MnCl₂, 1 nmol/L CoCl₂∙6H2O, 1.186 mmol/L vitamin B₁, 1.476 nmol/L vitamin B₁₂, and 8.186 nmol/L biotin) in a sterilized gas-phase injection vial (Agilent, Santa Clara, CA, USA) and cultured at 25 °C and 200 rpm/min in the dark for 12 h. The sample was tested by headspace gas chromatography (GC, Agilent 7890B, Santa Clara, CA, USA) without pretreatment. First, Dimethyl sulfide (DMS) in the sample was collected using a headspace sampler, and its concentration was detected by gas chromatography according to Williams’ method [36]. The consumption of DMSP in the sample was reflected by the content of equimolar DMS [37].