One-step biohydrogen production from cassava pulp using novel enrichment of anaerobic thermophilic bacteria community

Abstract

The aim of this study is to produce biohydrogen from untreated cassava pulp (CP) using a novel selected consortium of anaerobic thermophilic bacteria and the associated microbial communities were elucidated by metagenomic analysis. CP was chosen as a sole carbon source to enrich efficient hydrogen-producers from a total of 100 different composts and soil sediments under anaerobic dark fermentation at 60 °C. The stable enrichment culture was selected, base on CP degradation and hydrogen production. The selected consortium, namely BK16 from the residue of soil sediment around mangroves at Bangkhuntiean province, Thailand shows the highest hydrogen production yield (35.08 ml H 2 /g substrate) and hydrogen production rate (64.47 mL/day) in one-step. Besides, polysaccharide-degrading enzyme such as amylase, cellulase and xylanase of the BK16 were detected in culture supernatant at 70, 73 and 100 U/mg protein, respectively. In particular, the dominant microbes from selected consortium BK16 comprised of Clostridium thermopalmarium (61.2%) and Clostridium isatidis (25.3%) which have ability to degrade biomass and co-existed with acidogenesis bacteria, belong to the genus Thermoanaerobacterium (6.7%) and Fonticella tunisiensis (5.06%) to produced hydrogen as a consolidate bioprocess (CBP) system. The optimization condition for the hydrogen production of BK16 were at pH 7.0 and 10% (w/v) cassava pulp, in which 760 mL of H 2 /L was produced. Thus, these results revealed that the selected consortia BK16 can be used as an attractive candidate for direct hydrogen production, using cassava pulp as potential raw material for future bio-energy production. • The BK16 has isolated and identified the novel associated microbial communities. • Key biomass-degrading enzyme e.g., amylase, cellulase and xylanase were investigated. • One-step hydrogen production using non-pretreated cassava pulp were optimized.