Dark fermentation: isolation and characterization of hydrogen-producing strains from sludges

Autors/ores

  • Haifa Rajhi
  • Mónica Conthe
  • Daniel Puyol
  • Emiliano Díaz
  • José Luis Sanz

Resum

To improve bacterial hydrogen production, ten hydrogen-producing strains belonging to Clostridium spp.were isolated from various sludges under low vacuum. Hydrogenogenesis by dark fermentation in batch cultures of thesestrains was optimal at about 35 ºC and an initial pH of 6.5, which for all strains gradually dropped to ca. pH 4 during thefermentation. Clostridium roseum H5 and C. diolis RT2 had the highest hydrogen yields per total substrate (120 ml H2/ginitial COD). Substrate consumption alone by C. beijerinckii UAM and C. diolis RT2 reached 573 and 475 ml H2/gconsumed COD, respectively. Butyric acid fermentation was predominant, with butyrate and acetate as the majorby-products and propionate, ethanol, and lactate as secondary metabolites. The acetate:butyrate ratios and fermentationpathways varied depending on the strains and environmental conditions. Hydrogenogenesis was studied in greater detailin C. saccharobutylicum H1. In butyric acid fermentation by this representative strain, acetoacetate was detected as anintermediate metabolite. Hydrogenogenesis was also analyzed in an enrichment culture, which behaved similarly to theaxenic cultures. [Int Microbiol 2013; 16(1):53-62]

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Número

Vol. 16 Núm. 1 (2013)

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