Nh4 6mo7o24 4h2o

Phosphate buffer powder (consisting of Na₂HPO₄ and KH₂PO₄), methylene blue, sodium hydroxide (NaOH), potassium iodide (KI), and ammonium molybdate tetrahydrate ((NH₄)₆Mo₇O₂₄·4H₂O) were obtained from FUJIFILM Wako Pure Chemicals Corporation (Osaka, Japan). Potassium hydrogen phthalate (C₆H₄(COOK)(COOH)) was purchased from Tokyo Chemical Industry Co, Ltd (Tokyo, Japan). These chemicals were used without further purification.

All solvents were purchased from Kanto Chemical (Tokyo, Japan). (NH₄)₆Mo₇O₂₄·4H₂O and 30% H₂O₂ were purchased from FUJIFILM Wako Pure Chemical (Osaka, Japan). Liquid chromatography-high resolution electrospray ionization mass spectrometry (LC/MS) spectra were measured using an AB Sciex TripleTOF 5600+ System (AB Sciex, Framingham, MA, USA). All analyses were conducted in positive ion mode. Detailed conditions of MS analysis are shown as follows; Ion Source Gas1 50 psi; Ion Source Gas2 50 psi; Curtain Gas 25 psi; Temperature 500 °C; IonSpray Voltage Floating 5500 V; Declustering Potential 80 V; Collision Energy 45 V; Collision Energy Spread 15 V; Ion Release Delay 30 μs; and Ion Release Delay Width 15 μs. LC/MS data were analyzed by Analyst software (AB Sciex, version 1.7.1). Known microbial compounds were obtained from the natural compound library in the Kitasato Institute for Life Sciences.