title: Simple metabolite extraction method for metabolic profiling of the solid-state fermentation of Aspergillus oryzae.
abstract: Solid-state culture of microorganisms is an important style of culture both in the traditional food industry and in the modern fermentation industry. We propose here a simple method for metabolite extraction from the solid-state fermentation of a filamentous fungus, Aspergillus oryzae, which is known as rice-koji. To evaluate the efficiency of metabolite extraction, liquid chromatography-mass spectrometry (LC/MS) was used for simultaneous detection of a wide range of metabolites including amino acids, organic acids and vitamins, which are of interest in rice-koji making. Among eleven different metabolite extraction methods tested, we found that extraction using acetonitrile/water (50:50), coupled with boiling at 70 °C for 5 min, was advantageous in terms of both extraction yield and metabolism quenching. We consider that our method provides a technical basis for metabolome analysis of a solid-state fermentation.
authors.affiliation: National Research Institute of Brewing, 3-7-1 Kagamiyama, Higashihiroshima 739-0046, Japan. tokuoka@nrib.go.jp
authors.forename: Masafumi
authors.initials: M
authors.lastname: Tokuoka
authors.forename: Nobuko
authors.initials: N
authors.lastname: Sawamura
authors.forename: Ken
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Akihiro
authors.initials: A
authors.lastname: Mizuno
mesh_terms: D001236:Aspergillus oryzae / Q000378:metabolism*; D002623:Chemistry Techniques, Analytical; D002853:Chromatography, Liquid; D005285:Fermentation; D013058:Mass Spectrometry; D055442:Metabolome