Quantification of photopigments in strain PSB-S cells

Photopigments in strain PSB-S cells were extracted using a modified methanol/acetone extraction method [26]. The cells were collected by centrifuging, rinsed and resuspended in ddH₂O. Sonicated cell broth was extracted with methanol and acetone. The photopigment Carotenoid (Car) was then quantified by the Jassen formula, C = (D·V·f × 10)/2500 [C, Car quantification (mg); V, total volume of extract buffer; f, dilution fold; D, photodensity of Car at the maximum absorption peak]. The photopigment bacteriochlorin (Bchl) was calculated by the Beer-Lambert-Bouguer law, C = D·V·F/(a·L) × 10³ [a, extinction coefficient (L/g·cm); L, optical distance (cm)]. Quantification of total photopigments was determined by addition of Car and Bchl.