|"The absorption cross-section area of PSU [photosynthetic unit] in AAP bacteria
is much larger than that for PRP [proteorhodopsin-based phototrophic] bacteria, a major
difference between these two light-harvesting mechanisms.
The estimates for cultivated AAP bacteria range
from about 30×10^-20m^2 for an Erythrobacter strain to
over 70×10^-20m^2 for Roseobacter denitrificans (Table 4).
All of these estimates are about 10-fold larger than that of
PR [proteorhodopsin] and account for much of the difference in light energy
harvested by AAP and PRP bacteria. [Researchers] used the estimate
for a natural community, about 60×10^-20m^2 (Kolber
et al., 2001) for the linear response calculations." See note beneath table