Diazotrophic bacteria associated with banana (Musa spp.).

Nitrogen-fixing bacteria were isolated from surface sterilized banana (Musa spp.) plants and constituted a minor proportion of banana endophytic bacteria. Some isolates were characterized by alloenzyme profiles, biochemical tests, 16S rRNA and rpoB partial gene sequences, plasmid profiles and plant colonization. A large group of enterobacterial isolates that could not be clearly affiliated, most of them ascribed to group I (with characteristics of Enterobacter cloacae) were the diazotrophs most frequently found in banana. Different Klebsiella spp. and Rhizobiumsp. were identified as well. Klebsiella spp. were isolated from inside the roots and stems of plants grown in the two geographical regions sampled and from tissue culturederived plantlets. Rhizobium sp. isolates were obtained only from Colima where bananas are grown extensively. Group I isolates and Rhizobium sp. could be re-isolated from surface-sterilized banana derived from tissue culture at five months after inoculation and significant increases in stem and leave fresh weight were obtained with some of the isolates.