Burkholderia unamae sp. nov., an N2-fixing rhizospheric and endophytic species

Abstract

It was shown recently that the genus Burkholderia is rich in N2-fixing bacteria that are associated with plants. A group of these diazotrophic isolates with identical or very similar 16S rDNA restriction patterns [designated amplified rDNA restriction analysis (ARDRA) genotypes 13, 14 and 15] was selected and a polyphasic taxonomic study was performed, which included new isolates that were recovered from rhizospheres, rhizoplanes or internal tissues of maize, sugarcane and coffee plants. Morphological, physiological and biochemical features, as well as multi-locus enzyme electrophoresis profiles and whole-cell protein patterns, of 20 strains were analysed. In addition, analysis of cellular fatty acid profiles, 16S rDNA sequence analysis and DNA–DNA reassociation experiments were performed with representative strains. The taxonomic data indicated that the strains analysed belong to a novel diazotrophic Burkholderia species, for which the name Burkholderia unamae sp. nov. is proposed. Strain MTl-641T (=ATCC BAA-744T=CIP 107921T), isolated from the rhizosphere of maize, was designated as the type strain. B. unamae was found as an endophyte of plants grown in regions with climates ranging from semi-hot subhumid to hot humid, but not from plants grown in regions with semi-hot or hot dry climates. Moreover, B. unamae was isolated from rhizospheres and plants growing in soils with pH values in the range 4·5–7·1, but not from soils with pH values higher than 7·5.

Recent Studies on N2 Fixing Burkholderia Isolates as a Biofertilizer for the Sustainable Agriculture

“…Van Borm et al, (2002) recently showed that the micro flora inhabiting a pouch shaped organ at the junction of the midgut and the intestine of Tetraponera ants partially consists of Burkholderia species, which are most likely involved in the oxidative recycling of nitrogen rich waste. Growth and acetylene reduction was observed in B. unamae with different carbon sources in N-free semi solid BAz (Caballero-Mellado et al, 2004). In the present experiment, acetylene reduction assay in the isolates revealed that all the isolates showed nitrogenase activity and nitrogen fixation.…”

Suppression of Bacterial Wilt and Fusarium Wilt by a <i>Burkholderia nodosa</i> Strain Isolated from Kalimantan Soils, Indonesia

“…We checked by 16S rDNA sequences in 4 species but we did not sequence one isolate (G4.2), because in term of colony and substrate utilization of G4.1 and G4.2 isolates were similar. Fatty acid methyl ester profiles of strains C13.1, G4.1, G5.1 and G5.2 were compared with those of related Burkholderia species such us B. sacchari 4) , B. pyrrocinia 32) , B. terricola 11) , B. nodosa 6) , B. ferrariae 38) , B. unamae 5) and B. kururiensis 44) . The fatty acid profiles of strains C13.1, G4.1 and G5.1 were similar to those of B. sacchari, B. pyrrocinia and B. terricola, respectively.…”

Next generation of microbial inoculants for agriculture and bioremediation

“…In this regard, Burkholderia unamae represent an example of adapted bacteria with potential as PGPB to be applied in Mexican fields. B. unamae has the potential to fix nitrogen, produce phytohormones, siderophores and other inhibitory substances, ACC‐deaminase activity and degradation of toxic aromatic compounds (Caballero‐Mellado et al ., 2004, 2007; Onofre‐Lemus et al ., 2009). Nevertheless, as we mention before, effective bacteria for the crop field will be those able to express the genes responsible of the plant growth promotion or bioremediation in association with plants under real environmental conditions.…”