Isolation, characterization and associative N-fixation of acid-tolerant Azospirillum brasilense strains associated with Eleusine coracana in low pH-Al-rich acid soil

Five Azospirillum brasilense strains were isolated from the roots of finger millet (Eleusine coracana L.) plants grown in acid soils of Chhota Nagpur region of Bihar. These strains were characterized for their shape, size, motality, strain specific chemotaxis and nitrogen fixation ability in liquid medium containing different concentrations of AlCl3 and MnCl3 at different pH levels. These strains also showed cross-resistance to neomycin and penicillin but not to chloramphenicol and tetracyclin.