Indian Journal of Genetics and Plant Breeding (The)

The nitrogen fixing character was not so far attributed to the chemolithoauto-trophic group of microorganisms with the exception of Thiobacillus ferroxidans (MacKintosh, 1971). Since the investigations of Ooyama (1971) and Gogotov and Schlegel (1974) interest has been created in the new nitrogen fixing group of chemolithoautotrophic aerobic hydrogen bacteria. The present study examines newly isolated strains of hydrogen bacteria for their ability to fix nitrogen. One strain, 30-lb, studied in detail for its physiological behaviour and nitrogen fixation under different growth conditions, was identified to be Corynebacterium autotrophicum (Gaumgarten, Reh and Schlegel). The ability for N₂ fixation by 30-lb has been proved both under autotrophic and heterotrophic (sucrose) conditions. 30-lb grows well under aerobic conditions and does not grow under anaerobic conditions but requires microaerophilic condition during the process of N₂ fixation. It accumulates quite good amount of poly β-hydroxybutyric acid. The accumulation of the polymer was more under N₂ fixing conditions than in presence of ammonium chloride.