Some characteristics of Ag＋ biosorption and bioreduction by Lactobacillus sp. A09 biomass were reported. The optimum pH value of Ag＋ biosorption by strain A09 was 4.5. Temperature(6～ 50 ℃ ) did not affect the biosorption. The biosorptive efficiency (91％ ) and biosorptive capacity(Ag＋ 125 mg· g－ 1 dry weight biomass ) were achieved under the conditions of Ag＋ 100 mg· L－ 1, biomass 800 mg· L－ 1, pH 4.5 and 30 ℃ for 24 h contact. TEM analysis indicated that A09 biomass could reduce Ag＋ to Ag0 as Ag particles on the surface of cells. IR spectroscopy showed that － CO2－ and － HN－ C=O on the surface of cells may involve in the precession for adsorbing Ag＋ .
After widely screening, a kind of bacteria was obtamed, which is casy to culture and hasstrong ability of reducing Au3+ to Au0. It was used to prepare the highly dispersive Au/a-Fe2O3catalyst by in situ reducmg the Au3+ ions impregnated on a-Fe2O3 supporter to Au0 particles.with a mean size of 5 nm, under the condition of 28℃ and pH 4.5. The reductive degree ofAu3+ was up to 100%. This catalyst showed good catalytic property for the oxidation of carbonmonoxide, the percent conversion of 1.5% CO, balanced withe air was up to 100% under thecondition of 25~28℃and GHSV 500mL·h-1·g-1, and the percent conversion of 100% lastedfor 75 h at 25 ℃.
