L. Ragatz et al., MACROSCOPIC PHOTOTACTIC BEHAVIOR OF THE PURPLE PHOTOSYNTHETIC BACTERIUM RHODOSPIRILLUM-CENTENUM, Archives of microbiology, 163(1), 1995, pp. 1-6
Most photosynthetic microorganisms have the capability of photosensing
light quality and intensity. Movement of motile photosynthetic microo
rganisms to locales that offer optimal physical and chemical condition
s for light-dependent growth provides obvious selective advantages. Am
ong phototrophs, many cyanobacteria and algae migrate towards or away
from the direction of light, a process termed phototaxis. In contrast,
anoxygenic photosynthetic bacteria are believed to respond to changes
in light intensity in a manner that is not related to the direction o
f light, a process that is often described by the term ''photophobic''
. We recently reported that ''swarm colonies'' of the purple photosynt
hetic bacterium Rhodospirillum centenum are capable of macroscopically
visible phototactic behavior. In the present study we further charact
erize the phototactic behavior of R. centenum swarm colonies and provi
de an action spectrum that delineates re ions of the spectrum that eli
cit positive and negative phototaxis.