Abstract:
Background: the Miombo woodlands comprise the most important vegetation from
southern Africa and are dominated by tree legumes with an ecology highly driven by fires. Here, we
report on the characterization of bacterial communities from the rhizosphere of Brachystegia boehmii
in different soil types from areas subjected to different regimes. (2) Methods: bacterial communities
were identified through Illumina MiSeq sequencing (16S rRNA). Vigna unguiculata was used as a
trap to capture nitrogen-fixing bacteria and culture-dependent methods in selective media were
used to isolate plant growth promoting bacteria (PGPB). PGP traits were analysed and molecular
taxonomy of the purified isolates was performed. (3) Results: Bacterial communities in the Miombo
rhizosphere are highly diverse and driven by soil type and fire regime. Independent of the soil or
fire regime, the functional diversity was high, and the different consortia maintained the general
functions. A diverse pool of diazotrophs was isolated, and included symbiotic (e.g., Mesorhizobium sp.,
Neorhizobium galegae, Rhizobium sp., and Ensifer adhaerens), and non-symbiotic (e.g., Agrobacterium sp.,
Burkholderia sp., Cohnella sp., Microvirga sp., Pseudomonas sp., and Stenotrophomonas sp.) bacteria.
Several isolates presented cumulative PGP traits. (4) Conclusions: Although the dynamics of
bacterial communities from the Miombo rhizosphere is driven by fire, the maintenance of high levels
of diversity and functions remain unchanged, constituting a source of promising bacteria in terms
of plant-beneficial activities such as mobilization and acquisition of nutrients, mitigation of abiotic
stress, and modulation of plant hormone levels.
