Enhanced biohydrogen production from corn stover by the combination of Clostridium cellulolyticum and hydrogen fermentation bacteria

https://doi.org/10.1016/j.jbiosc.2016.03.014Get rights and content

Highlights

  • The yields of hydrogen production were improved in co-culture systems.

  • Formate acted as the predominant metabolite for carbon transfer in the co-culture.

  • Lower sugar concentrations were favorable for reaching high hydrogen yield.

Hydrogen was produced from steam-exploded corn stover by using a combination of the cellulolytic bacterium Clostridium cellulolyticum and non-cellulolytic hydrogen-producing bacteria. The highest hydrogen yield of the co-culture system with C. cellulolyticum and Citrobacter amalonaticus reached 51.9 L H2/kg total solid (TS). The metabolites from the co-culture system were significantly different from those of the mono-culture systems. Formate, which inhibits the growth of C. cellulolyticum, could be consumed by the hydrogen-evolving bacteria, and transformed into hydrogen. Glucose and xylose were released from corn stover via hydrolysis by C. cellulolyticum and were quickly utilized in dark fermentation with the co-cultured hydrogen-producing bacteria. Because the hydrolysis of corn stover by C. cellulolyticum was much slower than the utilization of glucose and xylose by the hydrogen-evolving bacteria, the sugar concentrations were always maintained at low levels, which favored a high hydrogen molar yield.

Section snippets

Materials and bacterial strains

Corn stover was harvested from a rural area near Beijing and pretreated by steam explosion as previously described (26).

The hydrogen-producing strains of E. aerogenes IAM1183 and C. paraputrificum M-21 were previously described by Lu et al. (9) The E. cloacae (NBRC 12935) and C. amalonaticus Y19 (NBRC 13547) strains were purchased from NBRC, and the cellulolytic strain of C. cellulolyticum (DSM 5812) was purchased from DSMZ.

Medium and cultivation

The preculture medium (1000 mL) for C. cellulolyticum consisted of

Hydrogen production from corn stover by co-culture fermentation

The strains used in this study include cellulolytic and non-cellulolytic mesophilic strains (Table 2). C. cellulolyticum was used as the cellulolytic bacterium. C. paraputrificum, C. amalonaticus, E. cloacae and E. aerogenes were used as the hydrogen fermentation bacteria. The optimum temperatures and pH ranges of the different strains were similar. The cellulolytic and non-cellulolytic hydrogen-evolving bacteria were paired to compare their hydrogen production efficiencies with 25 g/L

Acknowledgments

This work was supported by the National Key Technology R and D Program of China (2014BAD02B03) and the NSFC-JST Collaborating Research Project (21161140328).

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