Occurrence and biodiversity of Burkholderia spp. in natural environments or non-tillage soils of Argentina

DRAGHI, W.O.; DEGROSSI, J.; ABDIAN, P. L.; SOLER BISTUÉ, A.J.; WALL, L.G.; ZORREGUIETA, A.

Praga

Congreso; 15th Annual International Burkholderia cepacia Working Group Conference; 2011

International Burkholderia cepacia Working Group

The Burkholderia genus is a ubiquitous bacterial group occupying diverse niches in the environment, such assoils, plants or water sources, and displaying a wide range of biological features. Some of these activities include phytopathogenicity, plant growth promoting, endophytic or symbiotic nitrogen fixation, biological control of fungi and siderophore production. Although the clinical relevance of some strains is associated to the Burkholderia cepacia complex (Bcc), species comprise in this group showed relevant biological properties for plant health and growth. In the context of the BIOSPAS global project, a survey to recognize different Burkholderia strains in soils with different agricultural management within the main agricultural production area of Argentina was performed. Cultivable Burkholderia spp. on PCAT medium were identified by both Random Fragment Length Polymorphism (RFLP) with HaeIII digestion of an 869 bp recA amplicon and sequencing of a 384 bp recA fragment, according to Payne et al (3). Most of the isolates belonged to species from the Bcc, mainly B. ambifaria (55%) and B. cepacia (14%) strains. RFLP dendograms showed different patterns for Burkholderia isolates that belong to the same species, suggesting gene polymorphism or, alternatively the presence of new species that require a more detailed characterization. Although the quantification did not show any statistical difference among sites or treatments (reaching ca. 106 per gram of soil irrespective of soils types or agricultural managements) we observed differences in biodiversity indexes (Rarefaction, Simpson evenness Index), especially when comparing non-cultivated vs. cultivated soils. Further studies about the Burkholderia evolution in these soils will provide insight into the impact of agricultural management on the biodiversity of this genus.