Phosphate solubilization by bacteria and fungi grown in broth media (glucose-yeast extract/GYE) supplied with phosphate (Ca-P, Al-P and Fe-P) and carbon sources (cellulose, starch, sucrose, glucose, fructose and xylose) was evaluated under laboratory conditions. Growth, halo diameter, colony diameter and halo/colony ratio varied according to the microorganisms and phosphate or carbon sources. From 57 isolates, 56 were able to solubilize Ca-P with differing halo diameters, five succeeded to solubilize Al-P at different ranges and none was able to solubilize Fe-P. However, six isolates grew better in media supplied with Fe-P than in basal growth media (GYE). The largest colonies and halos were observed in cultures of Rhizopus and Aspergillus, whereas the largest halo/colony ratios were obtained with cultures of Paecilomyces and Penicillium. All microbial isolates were capable of growing in GYE but solubilization occurred only when a carbon source was added to the media, with better performance in the presence of xylose, glucose, fructose and sucrose.
calcium-phosphate; aluminum-phosphate; iron-phosphate; bacteria; fungi; cellulose; starch; sucrose; glucose; fructose; xylose