Yoshida Yusuke, Iguchi Hiroyuki, Sakai Yasuyoshi, Yurimoto Hiroya
a Division of Applied Life Sciences, Graduate School of Agriculture , Kyoto University , Kyoto , Japan.
b Department of Agriculture and Food Technology, Faculty of Bioenvironmental Science , Kyoto Gakuen University , Kameoka , Japan.
Biosci Biotechnol Biochem. 2019 Mar;83(3):569-577. doi: 10.1080/09168451.2018.1549935. Epub 2018 Nov 26.
A number of pink-pigmented facultative methylotrophs (PPFMs) belonging to Methylobacterium spp. isolated from living plant samples were found to require B vitamins for their growth in minimal medium, and most B vitamin-auxotrophic PPFMs required pantothenate (vitamin B). Further investigation of pantothenate auxotrophy using the representative strain Methylobacterium sp. OR01 demonstrated that this strain cannot synthesize β-alanine, one of the precursors of pantothenate. β-alanine and several precursors of pantothenate restored the growth of Methylobacterium sp. OR01 in minimal medium. Furthermore, this strain could colonize leaves of Arabidopsis thaliana cultivated in medium without pantothenate or its precursors. Pantothenate, β-alanine and several precursors were detected in the suspension of A. thaliana leaves. These results suggest that pantothenate-auxotrophic PPFMs can symbiotically colonize the surface of plant leaves by acquiring β-alanine and other precursors, in addition to pantothenate. Finally, the fitness advantage of B vitamin auxotrophy of PPFMs in the phyllosphere environment is discussed.
从活体植物样本中分离出的一些属于甲基营养型芽孢杆菌属的粉红色色素兼性甲基营养菌（PPFMs）被发现，在基本培养基中生长需要B族维生素，并且大多数B族维生素营养缺陷型PPFMs需要泛酸（维生素B5）。使用代表性菌株甲基营养型芽孢杆菌属OR01对泛酸营养缺陷型进行的进一步研究表明，该菌株无法合成泛酸的前体之一β-丙氨酸。β-丙氨酸和几种泛酸前体恢复了甲基营养型芽孢杆菌属OR01在基本培养基中的生长。此外，该菌株可以在不含泛酸或其前体的培养基中培养的拟南芥叶片上定殖。在拟南芥叶片的悬浮液中检测到了泛酸、β-丙氨酸和几种前体。这些结果表明，泛酸营养缺陷型PPFMs除了获取泛酸外，还可以通过获取β-丙氨酸和其他前体在植物叶片表面共生定殖。最后，讨论了PPFMs在叶际环境中B族维生素营养缺陷型的适应性优势。
