title: Production of ergothioneine by Methylobacterium species.
abstract: Metabolomic analysis revealed that Methylobacterium cells accumulate a large amount of ergothioneine (EGT), which is a sulfur-containing, non-proteinogenic, antioxidative amino acid derived from histidine. EGT biosynthesis and its role in methylotrophy and physiology for plant surface-symbiotic Methylobacterium species were investigated in this study. Almost all Methylobacterium type strains can synthesize EGT. We selected one of the most productive strains (M. aquaticum strain 22A isolated from a moss), and investigated the feasibility of fermentative EGT production through optimization of the culture condition. Methanol as a carbon source served as the best substrate for production. The productivity reached up to 1000 μg/100 ml culture (1200 μg/g wet weight cells, 6.3 mg/g dry weight) in 38 days. Next, we identified the genes (egtBD) responsible for EGT synthesis, and generated a deletion mutant defective in EGT production. Compared to the wild type, the mutant showed better growth on methanol and on the plant surface as well as severe susceptibility to heat treatment and irradiation of ultraviolet (UV) and sunlight. These results suggested that EGT is not involved in methylotrophy, but is involved in their phyllospheric lifestyle fitness of the genus in natural conditions.
authors.affiliation: Group of Plant-Microbe Interactions, Institute of Plant Science and Resources, Okayama University Okayama, Japan.
authors.forename: Kabir M
authors.initials: KM
authors.lastname: Alamgir
authors.affiliation: Group of Plant-Microbe Interactions, Institute of Plant Science and Resources, Okayama University Okayama, Japan ; Advanced Low Carbon Technology Research and Development Program, Japan Science and Technology Agency Tokyo, Japan.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Masuda
authors.affiliation: Group of Plant-Microbe Interactions, Institute of Plant Science and Resources, Okayama University Okayama, Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Fujitani
authors.affiliation: Laboratory of Pomology, Graduate School of Environmental and Life Science, Okayama University Okayama, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Fukuda
authors.affiliation: Group of Plant-Microbe Interactions, Institute of Plant Science and Resources, Okayama University Okayama, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Tani
keywords: Methylobacterium species; antioxidant; ergothioneine; glutathione; methanol; methylotroph; reactive oxygen species