Expression of a mineral phosphate solubilizing gene from Erwinia herbicolain two rhizobacterial strains

A genetic construction was carried out using the broad host range vector pK T230 and plasmid pMCG898, which encodes the Erwinia herbicola pyrroloquinol ine quinone (pQQ) synthase, a gene involved in mineral phosphate solubiliza tion (mps). The final construction was transformed and expressed in Escheri chia coli MC1061, and the recombinant plasmids were transferred to Burkhold eria cepacia IS-16 and Pseudomonas sp. PSS recipient cells by conjugation. Clones containing recombinant plasmids produced higher clearing halos in pl ates with insoluble phosphate as the unique (P) source, in comparison with those of strains without plasmids, demonstrating the heterologous expressio n of the E. herbicola gene in the recipient strains. This genetic manipulat ion allowed the increase in mps ability of both strains, enhancing their po tentialities as growth promoters of agricultural crops. These results repre sent the first report on the application of the recombinant DNA methodology for the obtainment of improved phosphate solubilizing ability from rhizoba cterial strains for biofertilization purposes. (C) 2000 Published by Elsevi er Science B.V.