title: Phyllosphere Methylobacterium bacteria contain UVA-absorbing compounds.
abstract: Microbes inhabiting the phyllosphere encounter harmful ultraviolet rays, and must develop adaptive strategies against this irradiation. In this study, we screened bacterial isolates originating from the phyllosphere of various plants which harbored absorbers of ultraviolet A (UVA), a wavelength range which is recognized as harmful to human skin. Of the 200 phyllosphere bacterial isolates we screened, methanol extracts from bacterial cells of seventeen isolates absorbed wavelengths in the range of 315-400nm. All of the UVA-absorbing strains belonged to Methylobacterium species based on 16S ribosomal RNA gene sequences, suggesting that cells of this bacterial genus contain specific UVA-absorbing compounds. When cells of a representative Methylobacterium strain were extracted using various solvents, UVA absorption was observed in the extracts obtained using several aqueous solvents, indicating that the UVA-absorbing compounds were highly polar. A compound was purified using solid columns and HPLC separation, and comparative analysis revealed that the absorption strength and spectrum of the compound were similar to those of the known UVA filter, avobenzone. The compound was also verified to be stable under UVA exposure for at least 480min. Based on these results, the UVA-absorbing compound harbored by Methylobacterium has potential to be used as a novel sunscreen ingredient.
authors.affiliation: Division of Plant Disease Management, Central Region Agricultural Research Center, NARO, 2-1-18, Kan-nondai, Tsukuba, Ibaraki 305-8666, Japan. Electronic address: yoshige@affrc.go.jp.
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Yoshida
authors.affiliation: Division of Hazardous Chemicals, National Institute for Agro-Environmental Sciences, 3-1-3, Kan-nondai, Tsukuba, Ibaraki 305-8604, Japan.
authors.forename: Syuntaro
authors.initials: S
authors.lastname: Hiradate
authors.affiliation: Division of Forage Crop Research, Institute of Livestock and Grassland Science, 768 Senbonmatsu, Nasushiobara, Tochigi 329-2793, Japan.
authors.forename: Motoo
authors.initials: M
authors.lastname: Koitabashi
authors.affiliation: Division of Biodiversity, National Institute for Agro-Environmental Sciences, 3-1-3, Kan-nondai, Tsukuba, Ibaraki 305-8604, Japan.
authors.forename: Tsunashi
authors.initials: T
authors.lastname: Kamo
authors.affiliation: Tokyo University of Agriculture, 1737, Funago, Atsugi, Kanagawa 243-0034, Japan.
authors.forename: Seiya
authors.initials: S
authors.lastname: Tsushima
mesh_terms: D001419:Bacteria / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification; D020580:Methylobacterium / Q000737:chemistry*; D010802:Phylogeny; D018515:Plant Leaves / Q000382:microbiology; D011427:Propiophenones / Q000494:pharmacology*; D013473:Sunscreening Agents / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: D011427:Propiophenones; D013473:Sunscreening Agents; C049935:avobenzone
keywords: Absorption; Methylobacterium; Phyllosphere; Ultraviolet A