[Encystment using different carbon substrates in Azotobacter chroococcum]

Carbon nutrition has a fundamental role in the encystment of bacteria of the genus Azotobacter. The effect of liquid media with various organic carbon substrates on the encystment of 2 strains of Azotobacter chroococcum was studied. Both strains had been previously cultured in a glucose and mannitol liquid medium. Strain 2087 showed the greatest degree of encystment (78%) with isopropanol and a very low percentage of cyst formation in the glucose and mannitol medium. In strain 1847 an important percentage of cyst formation (33%) was obtained in the glucose and mannitol medium and no cysts appeared with isopropanol. N-butanol and N-propanol induced in both strains relatively reduced percentages of encystment. The differential response found in the glucose and mannitol medium and the isopropanol media with strains 2087 and 1847 of A. chroococcum, has a degree of similarity in the different intensity of encystment shown by diverse strains of A. vinelandii with certain carbon substrates.