POTENTIAL UTILIZATION OF ANOXYGENIC PHOTOTROPS ISOLATED IN QATAR FOR RESOURCE RECOVERY OF VALUE-ADDED PRODUCTS

Abstract

Anoxygenic phototrophic bacteria (APB) are phylogenetically diverse group of organisms that can use both organic and inorganic electron donors for light-dependent fixation of carbon dioxide without generating oxygen. These bacteria vary broadly in terms of their metabolism as well as the composition of their photosynthetic apparatus. Among the APB, purple phototrophic bacteria have been extensively studied for their applications in wastewater treatment and in the production of value-added compounds such as single-cell proteins, carotenoid & bacteriochlorophyll pigments, polyhydroxyalkanoates and CoQ10. This research aims to (i) identify and culture APB present in a specific ecosystem within Qatar, (ii) investigate abiotic factors that influence the enrichment, community dynamics and generation of value-added compounds by these bacteria and (iii) utilize in silico protein modelling studies to enhance the substrate binding affinity of UbiA enzyme involved in the biosynthesis CoQ10, across several APB. These aims were met using growth analysis, 16S metagenomics, estimation of organic removal rates, bacteriochlorophyll, protein and CoQ10. Rational protein engineering methods were employed to improve the substrate binding affinity of the UbiA enzyme, present in several purple photosynthetic bacteria identified from the cultures. From this study, the ATCC 2728 medium was found to be ideal for APB enrichment, particularly purple phototrophic bacteria. Infrared light at 850 nm was most suitable for APB enrichment, while infrared light at 940 nm resulted in the highest amount of BChl a – 7.47 mg/g DCW. The enriched cultures under both types of IR light resulted in high amounts of CoQ10 >5.9 mg/g DCW. From the computational study, Rhodovulum marinum R97H UbiA mutant exhibited the best binding affinity with a docking score of -4.45 kcal/mol.

Date of Award	2023
Original language	American English
Awarding Institution	HBKU College of Health & Life Sciences