CHEMOTROPIC GROWTH OF HELIOBACTERIA IN DARKNESS

Conditions are described that support anaerobic dark chemotrophic grow th of heliobacteria. Growth was pyruvate-dependent and was best in wel l-buffered pyruvate media supplemented with yeast extract. Heliobacter ial cells grown in darkness synthesized bacteriochlorophyll g and caro tenoids and fermented pyruvate to acidic products, CO2, and in some ca ses, H-2. All recognized species of heliobacteria as well as several n ewly isolated strains were capable of dark anaerobic growth, suggestin g that this growth mode may be ecologically important for survival of these organisms in their soil habitat.