S. Inamdar et al., Longevity of Azotobacter cysts and a model for optimization of cyst density in liquid bioinoculants, CURRENT SCI, 78(6), 2000, pp. 719-722
Species of Azotobacter are known to form heat and desiccation-resistant cys
ts that have a long life span. Recently this property has been used to prep
are nitrogen-fixing liquid bioinoculants useful for a variety of crops. We
determined the survival of Azotobacter cysts in a liquid medium in order to
estimate the shelf-life of a liquid cyst bioinoculant. A negative exponent
ial model was fitted to the survivorship curve. The death rate was found to
increase with the initial density of cysts and ranged from 0.02 to 0.05 pe
r month. The nitrogen-fixing ability, on the other hand, dropped after two
years. The shelf-life of cyst bioinoculants therefore should be decided by
the nitrogen-fixing ability rather than cyst survival. Based on the derived
kinetics a model for optimization of cyst density in Azotobacter cyst-base
d liquid bioinoculants is proposed.