Enhanced carotenoid production by Rhodopseudomonas palustris ATCC 17001 under low light conditions

Carotenoids (CD) are biological pigments produced for commercial purposes. Therefore, it is necessary to study and determine the optimal conditions for increased CD production. There is no consensus in the literature about the conditions that increase CD production. Some authors stated that CD will be preferentially produced at low light intensities, at this adverse condition, microorganism will increase CD production as a survival response mechanism to get more energy. Other authors have mentioned that CD concentrations increase as the light intensity supplied increases, to avoid the overexposure of light and in turn photo-inhibition. Additionally, to increase the specific CD production is also necessary to increase the amount of biomass. In this work, the ammonium concentration (high (HAC) and low (LAC)) and the low light (LL) intensity effect on the CD production was evaluated. Data showed that a high CD-specific concentration of 8.8 mg/g_cell was obtained by using R. palustris ATCC 17001 under HAC and LL intensity. CD production was similar at HAC and LAC, suggesting that the light intensity has a greater effect on the specific CD concentration than the nitrogen concentration. In general, the results showed a low biomass production compared to the literature, with high CD synthesis.