Cultivation of the bacterium Azotobacter chroococcum for preparation of biofertilizers

The biomass of the bacterium Azotobacter chroococcum can be used as a biofertilizer due to its ability to fix nitrogen from the atmosphere. In order to optimize the production of bacterial biomass for this purpose, a cultivation of A. chroococcum was done by using different media and cultivation techniques (batch, fed batch and repeated batch). Chemically defined and complex media with 20 g/l of sugar were selected as the most appropriate media for batch cultivation in stirred tank bioreactor. In order to obtain higher fed batch and repeated batch techniques were examined. During these cultivations, increase of bioprocess efficiency parameters (yield coefficient and productivity) were observed compared with the batch cultivation. On the basis of the obtained results, repeated batch technique appeared to be the most suitable for the bacterial biomass production at industrial scale.