High performance liquid chromatography detection of phototrophic bacterial pigments in aquatic environments

Pigment extracts of phototrophic bacteria isolated from Lake Kinneret (Rhodopseudomonas palustris, Thiocapsa roseopersicina, Prosthecochloris aestuaris andChlorobium phaeobacteroides) were studied by means of high performance liquid chromatography (HPLC). An absorption wavelength of 360 nm provided the best resolution among the pigments of the species tested and between them and chlorophylla. Signature pigments were identified for each of these species, and their presence was thereby monitored in lake water samples.C. phaeobacteroides, which was observed in the anaerobic hypolimnion and predominated in the metalimnion, was recognized by a characteristic cluster of major chlorophyllous pigment peaks. The spectral qualities of these pigments were close but not identical to published data on bacteriochlorophylle, presumably due to the use of different solvents for extraction. The intensity of these pigment peaks was employed to determine the depth of the greatest phototrophic bacterial biomass, which was not related to that of algae.