Studies on Azotobacter chroococcum

Nitrogen fixing bacteria resembling Azotobacter were isolated from rhizosphere soil of different agricultural crops. Their morphological and biochemical properties were studied in detail to identify efficient ones for the preparation of bio-fertilizers. All the organisms were Gram-negative. There were both pigmented and non-pigmented forms. They also differed in their main physiological attributes like nitrogen fixation and synthesis of GLS and IAA like compounds. Nitrogen iixation ranged from 1.50 mg to 9.50 mg/g of sugar consumed. No correlation was observed between pigmentation and nitrogen fixation. Except the non-chromogenic strain (M-6), all the strains possessed different capacity to produce indole compounds ranging from 0.75 to 3.00 μg of IAA equivalents/ml of culture filtrates. All the strains were capable of synthesizing GLS, although they differed in their capacity, non-chromogenic strains like M-6 and W-3 were poor in synthesis of GLS.

Aus der Rhizosphäre verschiedener Kulturpflanzen wurden Azotobacter-Stämme isoliert und auf ihre morphologischen und biochemischen Eigenschaften untersucht, um besonders wirkungsvolle zur Herstellung von Biodüngern zu gewinnen. Unter den sämtlich Gram-negativen Stämmen gab es pigmentierte und nicht pigmentierte. Sie unterschieden sich auch in der N-Bindung (Schwankungsbreite 1,50 – 9,50 mg N/g Zucker) und in der Synthese Indolessigsäure(IAA)-ähnlicher Verbindungen (Schwankungsbreite 0,75 – 3,00 μg IAA-Äquivalente/ml Kulturfiltrat). Gibberellinsäure(GLS)-ähnliche Verbindungen wurden von allen Stämmen gebildet, von zweien allerdings nur in sehr geringer Menge.