Sodium-Dependent Growth of Azotobacter chroococcum

AUTOR(ES)
RESUMO

The majority of Azotobacter chroococcum strains in a collection obtained from Alberta soils were absolutely dependent on Na+ for growth. Two strains from the American Type Culture Collection also were either Na+ dependent or were stimulated by Na+. Optimal growth required 0.8 mM Na+ and was limited at 0.2 to 0.35 mM Na+. Growth promoted by 0.8 mM Na+ was inhibited by Rb+ > K+ >> NH4+ but was not affected by Li+. Growth inhibition by Rb+ and K+ was overcome by increasing the Na+ concentration present in the medium. Excellent growth in media containing limiting Na+ was obtained when 25 mM Li+ or 25 mM Mg2+ was added. Li+ was significantly more effective in replacing Na+ than was Mg2+. Na+ was required for growth on all C sources (glucose, sucrose, melibiose, and mannitol) and N sources (N2, NH4+, and NO3−) and was required throughout the pH range of growth. Cells suspended in Na+ -deficient medium or in distilled water did not appear to lyse or lose viability.

Documentos Relacionados