PIGMENTS OF RUBROBACTER-RADIOTOLERANS

The highly radioresistant Rubrobacter radio-tolerans,, contains red pi gments. Since the pigments could not be extracted by usual methods, a new method was developed in which the pigments were extracted with org anic solvents after addition of 10 N KOH to the intact cells, followed by neutralization. These pigments were also extracted after treatment with achromopeptidase, but not with lysozyme, The extracted pigments separated into two main spots by TLC (48.6% and 22.6%), and were confi rmed to be carotenoids by chemical tests. The two major pigments had 1 3 conjugated double bonds as determined from the main maximum waveleng th of the light absorption spectra. Their molecular weights were deter mined to be 740 and 722 by mass spectrometry. The mass spectra of thei r TMS-derivatives revealed that they contained four and three tertiary OH groups, respectively. Confirming their identical light and IR spec tra, these pigments were determined to be bacterioruberin and monoanhy drobacterioruberin, respectively, the characteristic carotenoids of ha lophilic bacteria. The existence of these pigments in bacteria other t han halobacteria provides interesting new evidence on the distribution of these compounds.