STUDIES ON THE PROTECTIVE FUNCTION OF THE CAROTENOID PIGMENTS OF SARCINA LUTEA

Abstract— An investigation was made of both the composition of and mechanism of photo-protection by the carotenoid pigments of Sarcina lutea ATCC 9341a and three induced mutants.
The wild-type and mutants 2a and 4b were each found to contain three major pigment fractions, each fraction consisting of a single pigment having identical absorption maxima but differing from each other in chromatographic mobility. Although the mutants contain the same kinds of pigments as does the wild-type, the mutant cells contain less pigment per cell than does the wild-type. The third mutant, 93a, contains no colored carotenoids.
It was found that there were changes in both the absolute and relative amounts of the various pigment fractions when cultures of wild-type, mutants 2a and 4b, grown in nutrient broth in the dark, were examined during the logarithmic and stationary phases of the growth curve. In addition, changes were observed in the pigments when the cells were exposed to light in buffer. These changes were similar in the wild-type and in mutant 2a, but were quite different in mutant 4b. Studies of photokilling curves suggested that these changes in amounts of the various pigment fractions were not related to photoprotection, but that the important factor may be the total amount of pigment per cell.