Enhancing Biodegradation of Pyridine with Trehalose Lipid in Rhodococcus pyridinivorans sp. Strain HR-1-Inoculated Microbial Fuel Cell

A Gram-positive exoelectrogen Rhodococcus pyridinivorans sp. strain HR-1 was cultivated from leachate-fed microbial fuel cell (MFC) to study the biodegradation effect of pyridine. In the comparison with mixed cultured MFC, HR-1 presented a remarkable electrical capacity with a maximum output of 4.33 W/m(3) under 30 degrees C in neutral anolyte with 1 g/L acetate as a substrate. Further, HR-1 demonstrated the environmental resistance as a Gram-positive strain. Microbial metabolism was evident at pH between 5-9 and temperature in the range of 20-40 degrees C, whereas optimal condition for pyridine degradation was observed at 30 degrees C. This is the first study reporting the degradation of pyridine in the bio-electrochemical system that achieved a 42% +/- 5% degradation rate in a full operation cycle at 2 g/L of the concentration. Considering the nonnegligible internal resistance of HR-1-inoculated MFC, trehalose lipid was also introduced as a bio-surfactant to reduce the charge transfer obstacle between the microbes and the electrodes. The surface morphology illustrated that the strain had a plump shape with a high specific area. Accordingly, bio-surfactant addition promoted the anode biomass (1.2 +/- 0.1 mg/cm(2) to 1.7 +/- 0.2 mg/cm(2)) and achieved a higher degradation rate (68% +/- 4%). The feasibility of electrochemical disposal on pyridine and eminent adaptability of strain sp. HR-1 as a Gram-positive exoelectrogen makes MFC a practical approach for real application.

Automated summary

Rhodococcus pyridinivorans HR-1 strain, a Gram-positive exoelectrogen, showed remarkable electrical capacity and biodegradation ability of pyridine in microbial fuel cells. Addition of bio-surfactant trehalose lipid improved the anode biomass and degradation rate.