The major ubiquinone system of strains of members of the genus Methylobacterium reported to date is ubiquinone Q-10. Similarly, strain 23eT had major ubiquinone system Q-10 (95 %) and minor Q-9 (5 %). The occurrence of ubiquinones Q-8, Q-9 and Q-11 as minor components in M. extorquens, M. fujisawaense and M. radiotolerans has been reported by Urakami et al. (1993). Ubiquinone system Q-9 has also been reported as a minor (2–7 %) component in type strains of M. mesophilicum, M. komagatae, M. brachiatum, M. tardum and M. hispanicum (Kato et al., 2008) and ‘M. soli’ (Cao et al., 2011). Thus strain 23eT had
an additional chemotaxonomic difference from its phylo- genetic relatives based on the presence of ubiquinone system Q-9