Abstract

The objective of the present work was to study the efficiency and diversity of nitrogen-fixing bacteria that colonize the weed Macroptilium lathyroides (L.) Urb. M. lathyroides roots were collected in areas of natural infestation of the species in rural and periurban areas of the municipality of Alta Floresta-MT, Brazil. The roots that presented nodulation were washed and their nodules removed, disinfected and inoculated in culture medium 79 in Petri dishes. These were incubated in a germination chamber in the dark at 28°C for 10 days, after which time the colonies were purified by streaking. The authentication experiment was conducted in a greenhouse and showed that of the 39 isolates, 19 of them had potential to be conducted for the nitrogen fixation efficiency test. The sequencing of the 16S rDNA gene identified the following bacteria that colonize the roots of the species: Mucilaginibacter gossypiicola, Novosphingobium arabidopsis, Bacillus haynesii, Bacillus xiamenensis, Bradyrhizobium namibiense and Flavobacterium anhuiense. Isolates M004, M005 and M022 showed values of nitrogen content very close to the ‘with N’ treatment, being indicated for further studies with commercially important cultures.

Key words: Diazotrophic bacteria, isolates, nodulation, rice bean.