In this study, we tried to explore the influence of various tricarboxylic acid (TCA) cycle intermediates on carotenoid production and with a focus on enhancing pigment biosynthesis, we conducted two statistical analysis. In case of TCA intermediates influence on pigment production by Paracoccus marcusii RSPO1; fumaric acid, and malic acid were observed as potent enhancers of pigment biosynthesis. Further, to optimize key media components for enhanced carotenoid production, the Plackett-Burman design was employed encompassing carbon, nitrogen sources, TCA cycle intermediates, and metal salts. The selected factors after Plackett Burman were fine-tuned through Response Surface Methodology and the optimal concentrations that have remarkably elevated carotenoid production were starch-2.24 g/l, MgSO4-0.416 g/l, ZnSO4-0.0157 g/l, and fumaric Acid-16 mM. Further, evaluation of pigment cytotoxicity against normal (Vero) and Non-Small Cell Carcinoma (A549) cells was performed. The resultant IC50 values were quantified as 161.3 µg/ml and 7.623 µg/ml for Vero and A549 cells, respectively. Moreover, a reactive oxygen species (ROS) determination study in A549 cells was done which have shown a noteworthy threefold ROS production in A549 cells through fluorescence spectroscopic observation. This implies that the bacterial carotenoids can act as potent pro-oxidants against cancerous cells while being nontoxic toward normal cells.
Keywords: Bacterial carotenoids; Plackett Burman design; cytotoxicity; reactive oxygen species; response surface methodology; tricarboxylic acid cycle intermediates.