FIG. 3.

Spectral analysis of photopigments of R. capsulatus wild-type B10S (A) and mutant strain M3-47 (B). M3-47 contains the hvrA mutation outlined in the legend to Fig. 1 in the background of strain W49I/R372I [nifA(Con) nifH-lacZYA]. Cells were grown for 48 h to late exponential phase (optical density at 660 nm, 1.0) under nitrogenase-repressing (15 mM ammonium, solid lines) or -derepressing (9.5 mM serine, hatched lines) high-light conditions (approximately 10,000 lx). BChla was extracted from equal amounts of cells, and spectral analysis was carried out as described previously (16).