Extractability of Carotenoid Pigments from Non-photosynthetic Bacteria with Solvents and Detergents: Implications for the Location and Binding of the Pigments

The extractability of carotenoid pigments from whole cells by sequential extraction at room temperature with polar and non-polar organic solvents, Triton X-100 and sodium dodecyl sulphate was studied in 40 pigmented, non-photosynthetic bacteria from 15 genera. The bacteria segregated into four groups according to the extractability of their pigments with detergent and methyl alcohol. There was no correlation between extractability and taxonomic status. Solvent and detergent extractions were effective with only 50% and 35% of the bacteria, respectively. Lyophilization of cells prior to extraction did not enhance extract-ability with solvents. Complete removal of the pigments from selected organisms with diethyl ether (following pretreatment with acetone) and with Triton X-100 could be obtained from cell wall and membrane fragments after disruption of the cells. A single extraction of wall and membrane fragments with methyl alcohol was effective in all but one case. The evidence indicates that the pigments are probably associated with protein and that the cell wall or intact membrane is the barrier to their extraction from whole cells.