Anaerobic granular sludge as a microbial platform for theconversion of gaseous substrates at moderate pressures

Abstract

As the end of fossil fuels-era is approaching, new biotechnological alternatives for biofuels and biochemicals production are emerging. Here we focus on the use of gaseous substrates, namely H2/CO2 and CO/H2/CO2 (syngas) as carbon and energy sources for the production of compounds with economical value, such as biomethane and fatty-acids by anaerobic granular sludge at moderate pressures up to 5×105 Pa. It was proven that anaerobic granular sludge can stand increased H2/CO2 pressure maintaining a high rate of methane production. On the other hand, the rise of syngas pressure up to 5×105 Pa led to a reduction on CO and H2 consumption rates and to a shift towards the formation of propionate and butyrate. The increase of initial H2/CO2 or syngas total pressure resulted in a specialization of the microbial communities. Anaerobic granular sludge was a stable and efficient microbial platform for the conversion of gaseous substrates.