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Title: Hydrogen transfer between methanogens and fermentative heterotrophs in hyperthermophilic cocultures

Interactions involving hydrogen transfer were studied in a coculture of two hyperthermophilic microorganisms: Thermotoga maritima, an anaerobic heterotroph, and Methanococcus jannaschii, a hydrogenotrophic methanogen. Cell densities of T. maritima increased 10-fold when cocultured with M. jannaschii at 85 C, and the methanogen was able to grow in the absence of externally supplied H{sub 2} and CO{sub 2}. The coculture could not be established if the two organisms were physically separated by a dialysis membrane, suggesting the importance of spatial proximity. The significance of spatial proximity was also supported by cell cytometry, where the methanogen was only found in cell sorts at or above 4.5 {micro}m in samples of the coculture in exponential phase. An unstructured mathematical model was used to compare the influence of hydrogen transport and metabolic properties on mesophilic and hyperthermophilic cocultures. Calculations suggest the increases in methanogenesis rates with temperature result from greater interactions between the methanogenic and fermentative organisms, as evidenced by the sharp decline in H{sub 2} concentration in the proximity of a hyperthermophilic methanogen. The experimental and modeling results presented here illustrate the need to consider the interactions within hyperthermophilic consortia when choosing isolation strategies and evaluating biotransformations at elevated temperatures.
Authors:
; ;  [1] ; ;  [2]
  1. Johns Hopkins Univ., Baltimore, MD (United States)
  2. North Carolina State Univ., Raleigh, NC (United States). Dept. of Chemical Engineering
Publication Date:
OSTI Identifier:
566365
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biotechnology and Bioengineering; Journal Volume: 56; Journal Issue: 3; Other Information: PBD: 5 Nov 1997
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; HYDROGEN TRANSFER; METHANOGENIC BACTERIA; BIODEGRADATION; REMEDIAL ACTION; MATHEMATICAL MODELS; CELL CULTURES; MASS TRANSFER; METABOLISM; TEMPERATURE DEPENDENCE; GENETIC VARIABILITY