Preparing DON Standards for Microbial Analysis

DON/3-keto-DON standards were purchased from TripleBond (Guelph, Canada), solubilized in sterile water to bring the initial concentrations to 1.0 mg/ml, filtered with 0.22 μm membrane filters, and stored at 4°C until used. Water was purified by a Milli-Q water system (Millipore Corporation, New York, USA). Mineral salt medium (MM) was formulated as described previously (Ikunaga et al., 2011 (link)), but with slight modifications. In brief, the medium contained 1.6 g of Na₂SO₄, 1.0 g of KH₂PO₄, 0.5 g of MgSO₄, 0.5 g of NaNO₃, 0.5 g of (NH₄)₂SO₄, 0.025 g of CaCl₂, and DON as the carbon source. Mineral salt-based medium (MSB) was composed of basic MM supplemented with 10% peptone. Luria-Bertani (LB) medium contained 10.0 g of tryptone, 5.0 g of yeast extract, and 10.0 g of NaCl. HPLC-grade methanol and analytical-grade ethyl acetate were obtained from Sinopharm (Shanghai, China). Cycloheximide was purchased from Solarbio (Beijing, China).