Publisher's Synopsis
Uric acid is the primary end product of purine in human metabolism and excess of uric acid may lead to gout, hyperuricemia and kidney disorder. The main objectives of the research were to isolate uric acid utilizing bacteria, their characterization, extraction of uricase enzyme and development of uric acid biosensor and a microbial fuel cell for power generation. Uric acid utilizing bacteria were isolated from soil and 16s rRNA sequences were used for strain identification. The isolates were identified as Pseudomonas sp.; Cupriavidus sp.; Pandoraea sp.; Comamonas sp.; Delftia sp. and Stenotrophomonas acidaminiphila. Comamonas sp BT UA was found most efficient in uric acid degradation. Crude enzyme was extracted, freeze-dried and purified and its Km and Vmax were determined as 40����M and 0.047����M min-1ml-1 with a specific activity of 80Umg-1 using Line-weaver Burk plot. This BT UA enzyme was immobilized on the working electrode with a biodegradable glutaraldehyde-crosslinked gelatin film. The polymer matrix on the working electrode gave capacitive response for in electrochemical impedance spectroscopy (EIS) study. Uric acid was estimated in human blood samples by the biosensor. For direct electron transfer and improvement, the uricase enzyme was activated electrochemically with ferrocene via cyclic voltammetry. The characterization of the electro-active enzyme was performed by surface plasmon resonance using ESPR, CD spectral analysis and fluorometry, atomic force microscopy and electrostatic force microscopy. The plausible interaction between Fc and uricase was proposed with molecular modeling. A new third generation uric acid biosensor was constructed by electro-activated uricase deposited within Nafion on glassy carbon electrode. The sensor system generated linear response at UA range of 500 nM to 600 ����M. Pseudomonas sp. BT 302 and Comamonas sp. BT UA were used for generation of electricity through a microbial fuel cell. CV and EIS were recorded for investigating the anode-biofilm electron transfer behavior. The mixed culture MFC produced current density and power density of 78.12 mA m-2 and 13.65 mW m-2, respectively with minimal internal resistance 576 ٠and 23 % coulombic yield.
