Abundance and ribotypes of phosphate-solubilizing bacteria in Argentinean agricultural soils under no-till management

LETICIA A. FERNÁNDEZ; BETINA AGARAS; LUIS WALL; CLAUDIO VALVERDE

ANNALS OF MICROBIOLOGY

INST MICROBIOLOGIA

Lugar: Milan; Año: 2015 vol. 65 p. 1667 - 1678

1590-4261

Phosphate solubilizing bacteria (PSB) abundance and ribotypes were examined in top soil (0-10 cm) of agricultural fields under no-till management sampled in two seasons: summer (February) and late winter (September), in 2010. No-till plots under sustainable agricultural practices (intense crop rotation) or under non-sustainable practices (soybean monocropping) were sampled at four different locations as replicates in a 400 km west-east transect at the most productive agricultural region of Argentina. Natural grasslands were selected close to the cultivated fields for comparative purposes. Culturable heterotrophic bacteria (CHB) were enumerated on nutrient agar plates and PSB were counted on NBRIP agar plates containing Ca3(PO4)2. The PSB community structure was explored by ribotyping (16S rDNA PCR-RFLP). Quantitatively, data showed that the number of CHB and PSB per g of dry soil was not statistically different among sampled sites, soil managements or seasons. Qualitatively, ribotyping showed that the most abundant PSB species differed in their fingerprinting patterns among geographical sites, which suggests that local soil conditions impose strong selective constrains. The comparative analysis of PSB ribotypes revealed seasonal differences among February and September isolates for all sampling sites.