Environmental pollution caused by aromatic compounds (ACs) has long stimulated the emergence of creative bioremediation strategies. Pseudomonas putida B6–2, an aerobic ACs degrading bacterium, successfully coupled ACs degradation with power generation in microbial fuel cells (MFCs) when a nickel-coated sponge with a three-dimensional macroporous structure served as the anode. The simultaneous removal of coexisting ACs pollutants including biphenyl (BP), carbazole (CA), and dibenzothiophene (DBT) were achieved in MFCs, accompanied by the efficient power densities of 469 mW m −2 , 499 mW m −2 , 541 mW m −2 , and 587 mW m −2 for single (BP), binary (BP+DBT or BP+CA), and ternary (BP+DBT+CA) ACs fueled MFCs, respectively. Degradation dynamics analysis indicated that the degradation of BP, CA, and DBT was consistent with the pseudo-first order kinetic model in the ternary ACs fueled MFC, and BP had a higher degradation rate ( k obs =0.0337 h –1 ) than DBT ( k obs =0.0201 h –1 ) and CA ( k obs =0.0149 h –1 ). It is the first time that P. putida B6–2 was discovered as an electroactive bacterium with high extracellular electron transfer (EET) capability. The EET preliminary analysis showed that P. putida B6–2 might transfer extracellular electrons by redox mediators and microbial nanowires . The mediators may play a key role in indirect EET at the start-up period of the MFCs, while the nanowires may involve in direct EET during the whole discharge process of the MFCs. The interesting findings may lay a foundation for further exploration of the EET of P. putida B6–2 and bioremediation of ACs pollutants.
This study investigates the advantages of combined microbial degradation of polycyclic aromatic hydrocarbons (PAHs) in reducing the inhibitory effects of high-concentration eluents commonly used in soil washing. A microbial synergistic strategy was proposed using Arthrobacter sp. SZ-3 and Pseudomonas putida B6-2 as the key bacteria in the presence of Tween 80. The results show that in systems with Tween 80, the SZ-3 strain exhibits a strong capacity to degrade three types of PAH compounds, while the B6-2 strain follows multiple degradation pathways. Mixed bacteria achieved degradation rates 60.70% higher than single bacteria at varying concentrations of Tween 80. Additionally, the average growth rates of mixed bacteria increased by 1.17–1.37 times, aligning with the changes in the functional group. Protein activity detection within each degradation system corresponded with growth quantity and the cyclic variation characteristics of ETS enzyme activity. Notably, the ETS activity of mixed bacteria was 150% higher than that of single bacteria. At a Tween 80 concentration of 500 mg/L, the degradation rates of PAHs (Phe, Flu, Pyr) by mixed bacteria were significantly higher than those by single bacteria. The catechol 1,2-dioxygenase activity of mixed bacteria was 2.30 times higher than that of single bacteria. While Tween 80 did not alter the PAH degradation pathways, it significantly influenced the accumulation amount and duration of the characteristic intermediate product. This provides a reference for the remediation of recalcitrant pollutants under conditions involving high-concentration surfactants.
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