Methylobacterium radiotolerans

In Methylobacterium radiotolerans (previously, Pseudomonas radiora), spirilloxanthin is the dominant component in the RC-LHI complex (Saitoh et al., 1995), while carotenoic acids are found in the outer membranes accompanied by no BChls and have nophotosynthetic functions (S. Saitoh, personal communication). Two species of Methylobacterium have also similar carotenoic acids with M radiotolerans, and two species of the forth group described above have polar carotenoids, diapocarotenoic acid derivatives. These highly polar carotenoids in the third, the forth and the fifth groups may be nonphotosynthetic carotenoids, which are not bound to the photosynthetic pigment-protein complexes (Shimada, 1995). Although their functions are not known, there is the possibility that they protect the photosynthetic apparatus from the outside aerobic conditions. 

Green PN, Bousfield U (1983) Emendation of Methylobacterium Patt, Cole, and Hanson 1976 Methylobacterium rhodirmm (Heumann 1962) cranb. nov. corrig. Methylobacterium radiotolerans (Ilo and lizuka 1971) comb. nov. cmrig. and Methylobacterium mesophilicum (Austin and Goodfellow 1979) comb. nov. bit J Syst Bacteriol 33 875-877... 

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