Molybdate reduction by Pseudomonas sp strain DRY2

摘要

Aims:To isolate and characterize a potent molybdenum-reducing bacterium.Methods and Results:A minimal salt medium supplemented with 10 mmol l-1 molybdate, glucose (1 center dot 0%, w/v) as a carbon source and ammonium sulfate (0 center dot 3%, w/v) as a nitrogen source was used in the screening process. A molybdenum-reducing bacterium was isolated and tentatively identified as Pseudomonas sp. strain DRY2 based on carbon utilization profiles using Biolog GN plates and partial 16S rDNA molecular phylogeny. Strain DRY2 produced 2 center dot 4, 3 center dot 2 and 6 center dot 2 times more molybdenum blue compared to Serratia marcescens strain DRY6, Enterobacter cloacae strain 48 and Eschericia coli K12, respectively. Molybdate reduction was optimum at 5 mmol l-1 phosphate. The optimum molybdate concentration that supported molybdate reduction at 5 mmol l-1 phosphate was between 15 and 25 mmol l-1. Molybdate reduction was optimum at 40 degrees C and at pH 6 center dot 0. Phosphate concentrations higher than 5 mmol l-1 strongly inhibited molybdate reduction. Inhibitors of electron transport system such as antimycin A, rotenone, sodium azide and cyanide did not inhibit the molybdenum-reducing enzyme activity. Chromium, copper, mercury and lead inhibited the molybdenum-reducing activity.Conclusions:A novel molybdenum-reducing bacterium with high molybdenum reduction capacity has been isolated.Significance and Impact of the Study:Molybdenum is an emerging global pollutant that is very toxic to ruminants. The characteristics of this bacterium suggest that it would be useful in the bioremediation of molybdenum pollutant.