Role of indigenous bacteria in dark fermentation of organic substrates

Hydrogen production by dark fermentation of complex organic substrates, such as biowaste, can naturally take place with indigenous bacteria or by adding an external microbial inoculum issued from various natural environments. This study aims to determine whether indigenous bacteria associated with thermal pretreatment could impact dark fermentation performances. Biochemical hydrogen potential tests were carried out on seven organic substrates. Results showed a strong influence of the indigenous bacteria which are as effective as thermally pretreated exogenous bacteria to produce H-2 and metabolites. High abundance in Clostridiales and/or Enterobacteriales was associated with high H-2 yield. This study shows that no inoculum nor pretreatment are required to achieve satisfactory dark fermentation performances from organic waste.