ISOLATION OF PHOSPHATE SOLUBILIZING BACTERIA (PSB) FROM PUNA GRASSLAND BY DYNAMIC ENRICHMENT IN CONTINUOUS CULTURE.

IOSA, F; FERNÁNDEZ, D; FERRERO M; LUCCA ME; SIÑERIZ F

Baltimore, USA

Congreso; Society for Industrial Microbiology Annual Meeting; 2006

Society for Industrial Microbiology

Phosphorous is normally the most limiting nutrient in Puna, a South American stressed biogeographic region with unique features. Microbial soil community are mainly formed by phosphate solubilizing bacteria (PSB) and arbuscular mycorrhizal fungi (AMF). Rhizospheric soil samples were taken along altitudinal gradient (3200 to 3800 masl) and phosphate solubilizing bacteria were isolated by dynamic enrichment in continuous culture. Batch culture of soil samples with a phosphorous limited culture medium (1uM of phosphorous)  were performed and continuous feeding at a dilution rate of  0.05 1/h allowed the isolation of different bacterial morphotypes. A Gram positive bacilli and a Gram positive cocci were isolated by this technique and identified by morphological, biochemical and molecular methods. The strains were subcultured on R2A agar medium and genomic DNA was extracted by the CTAB method in order to identified the isolates by PCR amplification and partial sequencing of 16S rRNA with universal primers for Bacteria F27, R518 and R1488. Biochemical properties were studied with API 50CHL, API 20A and API 20Strep (Biomerieux). One of the strains was identified as Alicyclobacillus acidocaldarius (99 % identity). Molecular analysis are carried out in order to identified the Gram positive cocci strain. Growth kinetic in batch culture of Alicyclobacillus acidocaldarius was studied at different phosphorous concentrations and maximal specific growth determined.