School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea.
School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea.
Biosens Bioelectron. 2020 Dec 15;170:112623. doi: 10.1016/j.bios.2020.112623. Epub 2020 Sep 24.
This study demonstrates the impact outer membrane permeability has on the power densities generated by E. coli-based microbial fuel cells with neutral red as the mediator, and how increasing the permeability improves the current generation. Experiments performed with several lipopolysaccharide (LPS) mutants (ΔwaaC, ΔwaaF and ΔwaaG) of E. coli BW25113 that increase the outer membrane permeability found the power generated by two of the truncated LPS mutants, i.e., ΔwaaC and ΔwaaF, to be significantly higher (5.6 and 6.9 mW/m, respectively) than that of the wild-type E. coli BW25113 (2.6 mW/m). Branched polyethyleneimine (BPEI, 400 mg/L), a strong chemical permeabilizer, was more effective, however, increasing the power output from E. coli BW25113 cultures to as much as 29.7 mW/m, or approximately 11-fold higher than the control MFC. BPEI also increased the activities of the mutant strains (to between 10.6 and 16.3 mW/m), as well as when benzyl viologen was the mediator. Additional tests found BPEI not only enhanced membrane permeability but also increased the zeta potential of the bacterial cells from a value of -43.4 mV to -21.0 mV. This led to a significant increase in auto-aggregation of the bacterial cells and, consequently, better adherence of the cells to the anode electrode, as was demonstrated using scanning electron microscopy. In conclusion, our study demonstrates the importance of outer membrane permeabilities on MFC performances and defines two benefits that BPEI offers when used within MFCs as an outer membrane permeabilizer.
本研究展示了外膜通透性对以中性红作为介体的大肠杆菌微生物燃料电池产生的功率密度的影响，以及增加通透性如何提高电流产生。对大肠杆菌 BW25113 的几种脂多糖（LPS）突变体（ΔwaaC、ΔwaaF 和 ΔwaaG）进行了实验，这些突变体增加了外膜通透性，发现两种截短的 LPS 突变体（ΔwaaC 和 ΔwaaF）产生的功率明显更高（分别为 5.6 和 6.9 mW/m），而野生型大肠杆菌 BW25113 的功率为 2.6 mW/m。然而，支化聚乙烯亚胺（BPEI，400 mg/L）作为一种强化学渗透剂更为有效，它将大肠杆菌 BW25113 培养物的功率输出增加到 29.7 mW/m，约比对照 MFC 高 11 倍。BPEI 还增加了突变株的活性（在 10.6 到 16.3 mW/m 之间），当使用苯并芘二酚作为介体时也是如此。进一步的测试发现，BPEI 不仅增强了膜通透性，还将细菌细胞的 zeta 电位从 -43.4 mV 增加到 -21.0 mV。这导致细菌细胞的自聚集显著增加，因此，正如扫描电子显微镜所证明的那样，细胞更好地附着在阳极电极上。总之，我们的研究表明了外膜通透性对 MFC 性能的重要性，并确定了 BPEI 作为 MFC 中外膜渗透剂使用时的两个好处。
