Biosorption of tungstate by a Bacillus sp. isolated from Anzali lagoon

Abstract

An attempt was made to isolate bacterial strains capable of biologically removing tungstate (WO 4 2-). Thirty-eight water samples were collected from various areas of Anzali lagoon, Iran. Initial screening of a total of 100 bacterial isolates at pH 5, resulted in the selection of one isolate with maximum adsorption capacity of 65.4 mg tungstate/g dry weight. It was tentatively identified as Bacillus sp. according to morphological and biochemical properties and named strain MGG-83. Tungsten concentration was measured spectrophotometrically using the dithiol method. Higher adsorption capacity was observed in the acidic pH ranging from 1 to 3. At pH 2, the strain removed 274.4 mg tungstate/g dry weight within 5 min from the solution with 300 mg WO 4 2-/l initial concentration and thereafter adsorption rate decreased remarkably. The applicability of the Freundlich isotherm for representation of the experimental data was investigated. Using 1 mM sodium azide and 10 mM 2,4-dinitrophenol, it was shown that only 20% reduction occurred in adsorption and steam sterilization of the bacterial cells resulted in 11% decrease in tungstate uptake. Temperature variations (20-40°C) had no significant effect on tungstate uptake. Pretreatment with the cations had no effect in uptake but pretreatment with anions decreased the tungstate uptake as indicated: sulfate > chromate > nitrate > molybdate > selenate > rhenate. Tungstate was removed from metal-laden biomass after desorption treatments by addition of different desorbing solutions with the results sodium acetate > EDTA > NaCl > KOH > H 2 SO 4 .

Toxic chromate reduction by resistant and sensitive bacteria isolated from tannery effluent contaminated soil

“…Watt and Ludden (1999) described the complete inhibition of Ni 2+ transport by KCN in Rhodospirillum rubrum, and NaN 3 has also been reported to inhibit tungstate uptake by Bacillus sp. (Malekzadeh et al 2007). …”

Bioprocessing of seleno-oxyanions and tellurite in a novel Bacillus sp. strain STG-83: A solution to removal of toxic oxyanions in presence of nitrate

“…Water samples were collected from different areas of the Anzali lagoon (in the southern coastal region of Caspian Sea, Gilan province, Iran) and Neidasht spring (in Mazandaran province, Iran), were enriched in Trypticase Soy Broth and cultured on agar plates to obtain separate colonies as described previously [15]. The broth cultures were incubated aerobically at 30 • C in a shaking incubator (150 rpm) and pH 7.0 for 72 h. Initially, 148 bacterial isolates were obtained and cultured in microtiter plates containing Luria Bertani medium (LB) plus 1-mM concentration of each of Na 2 SeO 3 , Na 2 SeO 4 (Sigma) and 0.1-mM K 2 TeO 3 (Merck) from filter-sterilized stock solutions to screen for the more resistant isolates.…”

Bacterial reduction of hexavalent molybdenum to molybdenum blue

“…This and coupled with the fact that a significant amount of the scheduled waste in Malaysia have been found to be illegally discharged and dumped (Mokhtar et al 2003) make molybdenum pollution a serious emerging threat. Resistance of microbes towards heavy metals can be used for their bioremediation of toxic metal ions (Liu et al 2007;Rehman et al 2007;Malekzadeh et al 2007;Zhu et al 2008). Bioremediation to treat molybdenum pollution was first carried out in Tyrol, Austria.…”