I. Reyes et al., Solubilization of phosphate rocks and minerals by a wild-type strain and two UV-induced mutants of Penicillium rugulosum, SOIL BIOL B, 33(12-13), 2001, pp. 1741-1747
Two Venezuelan phosphate rocks (PRs), apatite deposits from Monte-Fresco an
d Navay areas, and two minerals, Florida apatite and Utah variscite were us
ed to investigate phosphate solubilization by the wild type strain IR-94MF1
of Penicillium rugulosum initially selected for its high mineral phosphate
activity (Mps(+)) and two of its mutants Mps(++) and Mps(-). In liquid cul
tures, the three fungal strains showed better growth on the Navay PR than o
n Monte Fresco PR. The Utah variscite was the best phosphorus (P) source fo
r the growth of the wild type and the Mps(++) mutant. Solubilization of the
various P sources by the wild-type IR-94MF1 and the Mps(++) mutant resulte
d mostly from the action of organic acids. Citric acid seemed to be more ac
tive agent for the solubilization of the Utah variscite while gluconic acid
appeared to be responsible for the solubilization of the Florida apatite a
nd the Monte Fresco PR. Both organic acids are likely involved in the solub
ilization of the Navay PR. The Mps(+) mutant did not produce any organic ac
id when grown on all the P sources used. (C) 2001 Elsevier Science Ltd. All
rights reserved.