ISOLATION AND SELECTION OF THE STRAINS OF BACTERIA DECOMPOSING PHOSPHATE AND METHIDATHION (ORGANOPHOSPHORUS PESTICIDE) IN SOME SOIL TYPES IN PHU YEN

Abstract

Two strains of bacteria, VK1 and VK2, isolated from the agricultural soil of Phu Yen, are able to decompose phosphate and methidathion. The strain VK1 howed the highest phosphate – decomposing ability in cultured broth during 192 hours with 302.0 µg P/ml and in soil after 15 days with 472.33 ppm P. The concentration of methidathion has impact on the growth and the decomposing capability of strain VK1. Cultured at the concentration of 5µg methidathion/ml, the strain VK1 has the highest methidathion decomposing at 98.0% at the density of 91.5x109 (CFU/ml). In soil, after 20 days strain VK1 has methidathion decomposed with a considerable amount of 59.52%. compared with the control. When inoculated with the bacterial strain VK1, rice and green cabbage grew healthy and the content of photphate and the residues of methidathion in soil decreased considerably.