ISSN:
1432-072X
Keywords:
Key words Bacteriochlorophyll c
;
Bacteriochlorophyll a
;
Bacteriopheophytin c
;
Chlorobium tepidum
;
Chlorosome
;
Energy transfer
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Bacteriochlorophyll (BChl) c in whole cells of Chlorobium tepidum grown at 46 °C changed into bacteriopheophytin (BPhe) c within 10 days after reaching full growth. When a small amount of C. tepidum cells in which BChl c had been completely pheophytinized were transferred to a new culture medium, normal growth was observed after a short lag phase, and the absorption spectrum of the growing cells showed the presence of a normal amount of BChl c. During the growth of C. tepidum in the new culture, the BChl c concentration was nearly proportional to the cell density measured by turbidity (OD640). These results indicate that C. tepidum can survive even when BChl c has been completely pheophytinized and that BChl c is newly synthesized in such cells when transferred to a new culture medium. In partly pheophytinized cells, upon excitation of BPhe c at 550 nm the fluorescence emission spectrum showed maxima at 775 and 810 nm, which correspond to emissions from BChl c and BChl a, respectively. This indicates energy transfer from BPhe c to BChl c and BChl a. In cells in which BChl c was completely pheophytinized, fluorescence measurements were indicative of direct energy transfer from BPhe c to baseplate BChl a. These findings suggest that when BChl c in C. tepidum cells is pheophytinized, the product (BPhe c) remains in the chlorosomes and continues to work as a light-harvesting pigment.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002030050737
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