초록
<P><B>Abstract</B></P> <P>Self-fermentation of cellulosic substrates to produce biohydrogen without inoculum addition nor pretreatments was investigated. Dark fermentation of two different substrates made of leaf-shaped vegetable refuses (V) and leaf-shaped vegetable refuses plus potato peels (VP), was taken in consideration. Batch experiments were carried out, under two mesophilic anaerobic conditions (28 and 37？°C), in order to isolate and to identify potential H<SUB>2</SUB>-producing bacterial strains contained in the vegetable extracts. The effect of initial glucose concentration (at 1, 5 and 10？g/L) on fermentative H<SUB>2</SUB> production by the isolates was also evaluated.</P> <P>H<SUB>2</SUB> production from self-fermentation of both biomasses was found to be feasible, without methane evolution, showing the highest yield for V biomass at 28？°C (24？L/kg？VS). The pH control of the culture medium proved to be a critical parameter. The isolates had sequence similarities ≥98% with already known strains, belonging to the family <I>Enterobacteriaceae</I> (γ-<I>proteobacteria</I>) and <I>Streptococcaceae</I> (<I>Firmicutes</I>). Four genera found in the samples, namely <I>Pectobacterium</I>, <I>Raoultella</I>, <I>Rahnella</I> and <I>Lactococcus</I> have not been previously described for H<SUB>2</SUB> production from glucose. The isolates showed higher yield (1.6–2.2？mol？H<SUB>2</SUB>/mol？glucose<SUB>added</SUB>) at low glucose concentration (1？g/L), while the maximum H<SUB>2</SUB> production ranged from 410 to 1016？mL/L and was obtained at a substrate concentration of 10？g/L. The results suggested that vegetable waste can be effectively used as both, substrate and source of suitable microflora for bio-hydrogen production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We studied H<SUB>2</SUB> production by self-fermentation of non-pretreated organic waste, at two mesophilic temperatures (28 and 37？°C). </LI> <LI> H<SUB>2</SUB> can be produced with yield of about 23.9？L/kg of the substrate at 28？°C, only by control of pH by a proper buffer. </LI> <LI> Screening microbial diversity of the waste is a successful strategy to select new H<SUB>2</SUB>-producing bacteria. </LI> <LI> In batch experiments an inverse relationship between yield and volumetric hydrogen production occurs. </LI> </UL> </P>