Zinc solubilizing ability of
Pseudomonas fluorescent
was evaluated using zinc oxide, zinc
carbonate and zinc sulphide in both plate and broth media assays. Forty bacterial strains and 0.1% of each
chemical source in six replications were used. Colony and halo diameters were measured after incubating the
plates for 48h in incubator. Zn solubilizing ability of 40 mentioned strains in three replications was studied with
ZnO and ZnCO3 solutions in broth assay. The soluble zinc and pH were measured after five days. The results
showed, only 8 of 40 strains could form clearing zone in plate assay. Halo diameter, ratio of the halo diameter to
the colony diameter and area respectively for zinc oxide and zinc carbonate were as following, respectively: 0.60-
1.32 cm, 1.20-2.64 and 0.95-2.60 cm
2, 0.13-1.70 cm, 0.27-2.99 and 0.31-4.10 cm
2. There were no halos observed
in zinc sulphide. The concentration of soluble Zn for ZnO was 28-625 mg/l and pH was shifted from 7.0-7.2 to
3.90-6.50 and for ZnCO3 was 247-753 mg/l and pH was shifted from 7.0-7.2 to 3.5-6.3 after 5 days of inoculation
in 28°C.
