Isolation and characterization of two genetically distant groups of Acetobacter diazotrophicus from a new host plant Eleusine coracana L.

Abstract

Acetobacter diazotrophicus strains were isolated from Eleusine coracana, a new host plant cultivated along the coast of Tamil Nadu in India. Using a species‐specific oligonucleotide primer and PCR amplification, the presence of this bacterium was demonstrated directly in plant tissues, proving its endophytic nature, and it was absent in non‐rhizosphere soils. The isolates were also characterized on the basis of typical morphology, electron microscopy and biochemical tests, including nitrogen‐fixing efficiency, to assess their diversity. When RAPD analysis was performed on the isolates, they fell into two distinct genetically related groups when compared with the type strain PA1 5 (ATCC 49037). In view of the importance of E. coracana to this region, associated nitrogen‐fixing Acetobacter strains may be agronomically important because they could supply part of the nitrogen that the crop requires.