MANIPULATION OF THE BACTERIOCHLOROPHYLL-C HOMOLOG DISTRIBUTION IN THEGREEN SULFUR BACTERIUM CHLOROBIUM-TEPIDUM

wWe have shown that the green sulfur bacterium Chlorobium tepidum can be grown in batch culture supplemented with potentially toxic fatty al cohols without a major effect on the growth rate if the concentration of the alcohols is kept low either by programmed addition or by adding the alcohol as an inclusion complex with P-cyclodextrin. HPLC and GC analysis of pigment extracts from the supplemented cells showed that t he fatty alcohols were incorporated into bacteriochlorophyll c as the esterifying alcohol. It was possible to change up to 43% of the natura lly occurring farnesyl ester of bacteriochlorophyll c with the added a lcohol. This change in the homolog composition Rad no effect on the sp ectral properties of the cells when farnesol was partially replaced by stearol, phytol or geranylgeraniol. However, with dodecanol we obtain ed a blue-shift of 6 nm of the Q(y) band of the bacteriochlorophyll c and a concomitant change in the fluorescence emission was observed. Th e possible significance of these findings is discussed in the light of current ideas about bacteriochlorophyll organization in the chlorosom es.