The effect of inhibitors of carotenoid synthesis, diphenylamine, acridine, and aeriflavin on catalase induction was studied in t~hodopseudomonas spheroides. The induction of catalase by 40 ~ H~O~, was inhibited 5 β’ 10 -a M acridine, 5 ~M acriflavin and 3β’ -a diphenylamine. Acridine, acrillavin and diphenylamine at 1.0 β’ 10 -4 M, 1.5 ~ and 5 β’ 10 -5 M respectively, stimulated the induction. The stimulatory effect was shown to be at the transcriptional level rather than at the translational level. The concentration of acridine which stimulated the induction of the enzyme inhibited general protein synthesis in the cell, under similar conditions. Acriflavin also did not stimulate the induction of fl-galactosidase in Escherichla coll B. It is suggested that these acridine dyes interact with the internal inducer-DNA complex which leads to a higher rate of production of catalase ml~NA.
During photosynthetic growth in Rh. spheroides the bulk of the carotenoids is spheroidene. When the anaerobic culture is aerated, spheroidene is converted to spheroidenone (Cohen-Bazire et al., 1957;Eimhjellen and Jensen, 1964). When air is introduced into the anaerobic culture, the enzyme eatalase is also induced (Clayton, 1960a;Shanmugam and Berger, 1969). Although diphenylamine is known to inhibit the growth in Rh. spheroides, it inhibits specifically the carotenoid synthesis in other photosynthetic bacteria (Cohen-Bazire and Stanier, 1958). Rilling (1965) found that acridine dyes also inhibit the carotenogenesis in Mycobacterium. Many of the acridine dyes are known to intercalate with DNA and inhibit DNA-function (Blake and Peacoke, 1968). Higuchi et al. (1965), found that acriflavin (2,8-diamino, N-methyl acridine) inhibits the synthesis of caC~lase. These facts led to the present