Novel application of peptaibiotics derived from Trichoderma sp. for methanogenic suppression and enhanced power generation in microbial fuel cells

Abstract

A major limitation to achieve higher power output from microbial fuel cells (MFC) is the development of competitive environment for substrate utilization offered by methanogenic archaea. This study reveals the comparative electrical performance of MFC, where the enrichment of anodic electrogenic inoculum was done with two low-cost peptaibiotics recovered from Trichoderma sp. Membrane active, pore-forming compounds such as the peptaibiotics Trichotoxin A-40 and Alamethicin F-50 were found in T. viride extract, whereas, Neoatroviridin (A-D) was retrieved from T. atroviride. Upon treatment of mixed anaerobic sewage sludge, used as the inoculum in MFC, respective power densities of 205.40 mW m⁻² (790 mA m⁻²) and 306.03 mW m⁻² (1010 mA m⁻²) were demonstrated by MFCs with significantly high coulombic efficiencies of 48.7% and 53.5%, respectively. These power densities were 3.4 and 2.4 times higher than that was produced by the control MFC, operated without pre-treating the inoculum with fungal extract. The inhibitory effect on methanogens was sustained even after 15 batch cycles of MFC operation, demonstrating no adverse effect of such peptaibiotics on electrogens, but providing a non-competitive environment for their growth by effectively inhibiting methanogens and considerably enhancing the power recovery from MFC.