Background Pseudomonas stutzeri S116 is a sulfur-oxidizing bacteria isolated from marine sludge. It exhibited excellent electricity generation as bioanode and biocathode applied in microbial fuel cells (MFCs). Complete genome sequencing of P. stutzeri and cyclic voltammetry method were performed to reveal its mechanism in microbial fuel cells system. Results This study indicated that the MFCs generated a maximum output voltage of 254.2 mV and 226.0 mV, and maximum power density of 765 mW/m2 and 656.6 mW/m2 respectively. Complete genome sequencing of P. stutzeri S116 was performed to indicate that most function genes showed high similarities with P. stutzeri, and its primary annotations were associated with energy production and conversion (6.84%), amino acid transport and metabolism (6.82%) and inorganic ion transport and metabolism (6.77%). Homology of 36 genes involved in oxidative phosphorylation was detected, which suggests the strain S116 possesses an integrated electron transport chain. Additionally, many genes encoding pilus-assembly proteins and redox mediators (riboflavin and phenazine) were detected in the databases. Thiosulfate oxidization and dissimilatory nitrate reduction were annotated in the sulfur metabolism pathway and nitrogen metabolism pathway, respectively. Gene function analysis and cyclic voltammetry indicated that P. stutzeri probably possesses cellular machinery such as cytochrome c and redox mediators and can perform extracellular electron transfer and produce electricity in MFCs. Conclusion The redox mediators secreted by P. stutzeri S116 were probably responsible for performance of MFCs. The critical genes and metabolic pathways involved in thiosulfate oxide and nitrate reduction were detected, which indicated that the strain can treat wastewater containing sulfide and nitrite efficiently.

To identify suitable biocatalysts applied in microbial fuel cells (MFCs), Pseudomonas stutzeri S116 isolated from marine sludge was investigated, which possessed excellcent bioelectricity generation ability (BGA). Herein, P. stutzeri as a bioanode and biocathode achieved maximum output voltage (254.2 mV and 226.0 mV), and power density of (765 mW/m2 and 656.6 mW/m2). Complete genome sequencing of P. stutzeri was performed to reveal its potential microbial functions. The results exhibited that the strain was the ecologically dominant Pseudomonas, and its primary annotations were associated with energy production and conversion (6.84%), amino acid transport and metabolism (6.82%) and inorganic ion transport and metabolism (6.77%). The thirty-six genes involved in oxidative phosphorylation indicate that strain possesses an integrated electron transport chain. Moreover, many genes encoding redox mediators (mainly riboflavin and phenazine) were detected in the databases. Simultaneously, thiosulfate oxidization and dissimilatory nitrate reduction were annotated in the sulfur metabolism and nitrogen metabolism pathway. Gene function and cyclic voltammetry (CV) analysis indicated BGA of P. stutzeri probably was attributed to its cytochrome c and redox mediators, which enhance extracellular electron transfer (EET) rate.

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