Spectral Changes in Anacystis nidulans Induced by Chilling.

When Anacystis nidulans, strain TX 20 was grown at 39 C, then rapidly chilled to 0 C, a pigment with a carotenoid-like spectrum was bleached. This effect was not seen when cells which had been grown at 25 C were chilled. The effect seen in 39 C-grown cells was not reversible except under extreme conditions such as heating to near boiling for several minutes. Bleaching could be prevented by prior exposure of cells to glutaraldehyde, but could not be reversed by glutaraldehyde treatment following chilling. The effect occurred upon chilling 39 C-grown cells even after extensive heating at 85 C, a treatment which destroys phycocyanin and metabolic activities. 25 C-grown cells were induced to bleach by chilling when suspended in 50% glycerol. The results are interpreted as indicating a chill-induced change in aggregation state of a carotenoid, which changes its specific absorbance.