ABSTRACT
The pigment composition of “
Candidatus
Chlorothrix halophila,” a filamentous anoxygenic phototrophic bacterium found in Baja California Sur, Mexico, was determined. Previous work showed that bacteriochlorophyll
c
(BChl
c
) was the major pigment in “
Ca
. Chlorothrix halophila,” but it was not clear if this bacterium also contains BChl
a
(J. A. Klappenbach and B. K. Pierson, Arch. Microbiol.
181:
17-25, 2004). Here we show that in addition to BChl
c
, a small amount of a pigment that is spectrally indistinguishable from BChl
a
is present in cell extracts of “
Ca
. Chlorothrix halophila.” Nevertheless, the BChl
a
-like pigment from “
Ca
. Chlorothrix halophila” has a different molecular weight and a different high-performance liquid chromatography elution time than BChl
a
from other photosynthetic bacteria. Based on mass spectrometry and other spectroscopic analysis, we determined that the BChl
a
-like pigment in “
Ca
. Chlorothrix halophila” contains a tetrahydrogeranylgeraniol tail rather than the phytol tail that is present in BChl
a
. The carotenoids and major BChl
c
homologs in “
Ca
. Chlorothrix halophila” were also identified. BChls
c
were found to be farnesol esterified and geranylgeraniol esterified.