The stability of biological H 2 production and microbial diversity by anaerobic sludge treated chloroform with different concentrations were investigated in this work. Taking into account the cumulative H 2 production, H 2 percentage, maximum H 2 production rate, H 2 yield and substrate utilization efficiency together, 0.050% of CHCl 3 concentration was found to be appropriate for enhancing anaerobic H 2 production. The repeated batch tests revealed a good stability of H 2 production with the inocula treated by chloroform at different concentrations. Denaturing gradient gel electrophoresis (DGGE) analysis demonstrates that CHCl 3 showed desirable selective inhibition on methanogens, rather than H 2 -producing bacteria. The favorable microbial communities for fermentative H 2 production by anaerobic sludge were uncultured bacterium clones nbt176c01, Janthinobacterium sp.7, Megasphaera paucivorans strain VTT E−03234, Clostridium cellulosi strain D3 and Clostridium sp. HPB-4.
