Abstract

BECERRA, JULIANA M.; QUINTERO, DIANA; MARTINEZ, MARÍA  and  MATIZ, ADRIANA. Characterization of phosphate solubilizing microorganisms isolated from soils planted with cape gooseberry (Physalis peruviana L.). rev.colomb.cienc.hortic. [online]. 2011, vol.5, n.2, pp.195-208. ISSN 2011-2173.

Soil samples of cape gooseberry crops from two production areas of Cundinamarca (Colombia) were used to isolate phosphate solubilizing microorganisms. The culture medium SMRS1 was used to perform qualitative solubilization tests by identifying the formation of clear zones around the colonies with rock phosphate. Five strains were isolated with a solubilizing capacity and subsequently three out of the five were selected according to their solubilization index. The P-solubilization index of these isolates ranged from 2.4 to 3.0. The selected strains were identified with API kits as Candida famata, Aeromonas hydrophila and Rahnella aquatilis. Then, a growth curve was made for each, testing three different culture mediums considered as treatments: modified AG medium, AG medium and quinoa BR medium; with SMRS and SMRS1 as the controls. The evaluation of phosphatase activity was carried out in two phases, each under different conditions, with the p-nitrophenylphosphate method. A production of acid phosphatases was observed. Although the phosphatase activity of individual strains was detected at very low concentrations in both phases, we found that their activity can be potentiated as a mixed inoculum. As no antagonism was present between strains, they could be a suitable option for the future development of mixed bioinoculants for acid soils. The BR medium was also found to potentially be a viable alternative for the growth of phosphate solubilizing microorganisms.

Keywords : organic acids; biofertilizer; phosphatase.

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