Isolation and characterization of some chemoautotrophic Chromatiaceae

Abstract
Three strains of facultatively chemoautotrophic Chromatiaceae were isolated from natural habitats under chemotrophic conditions and identified as Chromatium gracile (strains 23‐3 and 25‐1) and Thiocapsa roseopersicina (strain Laboe). The strains utilized hydrogen and reduced sulfur compounds for photo‐ and chemolithoautotrophic growth. Ammonium or dinitrogen were utilized as nitrogen sources for photo‐ and chemotrophic growth. With most of the organic carbon compounds examined chemoheterotrophic growth was dependend on the presence of a reduced sulfur compound. The newly isolated strains grew chemoorganotrophically with fumarate, fructose as well as with some short‐chain fatty acids and aliphatic alcohols. The determination of the respiratory activity of Chromatium gracile 25‐1 revealed that the utilization of butyrate for chemotrophic growth was not constitutive. The maximal respiratory activity of phototrophically grown Chromatium gracile 25‐1 was 2 times higher than that of other facultative chemotrophic Chromatiaceae. The respiratory activity of the obligately phototrophic Thiocapsa pfennigii was similar to that of phototrophically grown facultatively chemotrophic Chromatiaceae.