Glucose fermentation to methane and CO2 by defined mixed cultures

Abstract

The degradation of glucose to methane and CO₂ by mixed cultures of Escherichia coli, Bifidobacterium bifidum, Desulfovibrio desulfuricans and methanogens was investigated. Glucose degradation in mixed cultures of E. coli with H₂: CO₂-fermenting and formate-fermenting methanogens resulted in acetate, ethanol, CO₂ and methane formation. When Methanosarcina barkeri was combined with E. coli, CO₂, methane and — due to incomplete hydrogen transfer — ethanol were produced.

No methane was generated in mixed cultures of B. bifidum and Methanobrevibacter arboriphilus, and only little of this compound was produced from formate in mixed cultures of B. bifidum and Methanobrevib acter smithii or Methanobacterium formicicum. The combination of B. bifidum and M. barkeri produced methane from acetate, but ethanol and formate could not be degraded.

In mixed cultures of B. bifidum, D. desulfuricans and H₂: CO₂-utilizing as well as formate-fermenting methanogens, CO₂, methane, acetate and little ethanol was formed. A virtually complete conversion of glucose to methane and CO₂ took place when B. bifidum, D. desulfuricans and M. barkeri were members of the consortium.