AimsTo improve the oxygen-tolerant capability of a newly isolated anaerobic bacterium and to biosynthesize O-desmethylangolensin (O-Dma) from daidzein aerobically. Methods and ResultsAfter a long-term domestication process, an oxygen-tolerant bacterium, which we named Aeroto-AUH-JLC108, was derived from the newly isolated obligate anaerobic bacterium Clostridium sp. AUH-JLC108. Strain Aeroto-AUH-JLC108 differed from the natively anaerobic wild-type strain AUH-JLC108 by various characteristics, including a change in bacterial shape, biochemical characteristics and 16S rRNA gene sequences. Both the growth speed and the maximal optical density (OD) value of strain Aeroto-AUH-JLC108 grown aerobically were significantly increased compared to that of the wild-type strain grown anaerobically. The maximal concentration of the substrate daidzein that the oxygen-tolerant strain Aeroto-AUH-JLC108 grown aerobically was able to convert efficiently was 20mmoll(-1) and 06mmoll(-1) for strain AUH-JLC108 that was grown anaerobically. ConclusionsStrain Aeroto-AUH-JLC108 is a conditional oxygen-tolerant bacterium. The growth speed, bacterial growth mass and bioconversion capability of strain Aeroto-AUH-JLC108 grown aerobically was significantly increased compared to that of the wild-type strain AUH-JLC108 grown anaerobically. Significance and Impact of the StudyStrain Aeroto-AUH-JLC108 is the first reported pure culture responsible for the formation of O-Dma from daidzein in the presence of atmospheric oxygen.