One of the most economical approaches for removal of toxic compounds is bioremediation. In the long term, bioremediation is economic and feasible compared to other methods, such as physical or chemical methods. A bacterium that can efficiently reduce molybdenum blue was isolated from polluted soil. Biochemical analysis revealed the identity of the bacterium as Enterobacter sp. strain Saw-1. The growth parameters for optimal reduction of molybdenum to Mo-blue or molybdenum blue, a less toxic product, were determined around pH 6.0 to 6.5 and in the range of 30 to 37 degrees C, respectively. Glucose was selected as preferred carbon source, followed by sucrose, maltose, 1-rhamnose, cellobiose, melibiose, raffinose, d-mannose, lactose, glycerol, dadonitol, d-mannitol, 1-arabinose and mucate. Phosphate and molybdate were critically required at 5.0 mM and 10 mM, respectively. The scanning absorption spectrum acquired to detect the development of complex Mo-blue showed similarity to previously isolated Mo-reducing bacteria. In addition, the spectrum closely resembled the molybdenum blue from the phosphate determination method. Heavy metals, including mercury, copper (II) and silver (I), inhibited reduction. Moreover, the bacterium also showed capability of exploiting the pesticide coumaphos as an alternative carbon source for growth. As the bacterium proved its ability to detoxify organic and inorganic xenobiotics, the usefulness of this microorganism for bioremediation is highlighted.

Molybdenum and heavy metals are toxicants that are needed to be removed from the environment as they are non-biodegradable and pose a serious threat to the ecology. A previously isolated keratin-degrading Bacillus sp. strain khayat was shown to be able to reduce molybdenum (sodium molybdate) to molybdenum blue (Mo-blue). Reduction occurred optimally at the pHs of between 5.8 and 6.8 and temperatures of between 25 and 34 A degrees C. Glucose was the best electron donor for supporting molybdate reduction followed by sucrose, fructose, glycogen, lactose, meso-inositol and glycerol in descending order. Other requirements include a phosphate concentration between 5.0 and 7.5 mM and a molybdate concentration of between 10 and 20 mM. The absorption spectrum of the Mo-blue produced was similar to previous Mo-reducing bacterium, and closely resembles a reduced phosphomolybdate. Molybdenum reduction was inhibited by Hg (ii), Ag (i), Cu (ii), As (v) and Pb (ii) at 84.7, 78.9, 53.5, 36.8 and 27.7 %, respectively. Analysis using phylogenetic analysis resulted in a tentative identification of the bacterium as Bacillus sp. strain khayat. The bacterium was unable utilize any of the xenobiotics as sources of electron donor for reduction but the bacterium was able to grow on diesel and SDS. The ability of this bacterium to detoxify several toxicants makes this bacterium an important tool for bioremediation of multiple toxicants.

Bioremediation of pollutants including heavy metals and xenobiotics is an economic and environmentally friendly process. A novel molybdenum-reducing bacterium with the ability to utilize the pesticide glyphosate as a carbon source is reported. The characterization works were carried out utilizing bacterial resting cells in a microplate format. The bacterium reduces molybdate to Mo-blue optimally between pH 6.3 and 6.8 and at 34 degrees C. Glucose was the best electron donor for supporting molybdate reduction followed by lactose, maltose, melibiose, raffinose, d-mannitol, d-xylose, I-rhamnose, I-arabinose, dulcitol, myo-inositol and glycerol in descending order. Other requirements include a phosphate concentration at 5.0 mM and a molybdate concentration between 20 and 30 mM. The molybdenum blue exhibited an absorption spectrum resembling a reduced phosphomolybdate. Molybdenum reduction was inhibited by mercury, silver, cadmium and copper at 2 ppm by 45.5, 26.0, 18.5 and 16.3%, respectively. Biochemical analysis identified the bacterium as Klebsiella oxytoca strain Saw-5. To conclude, the capacity of this bacterium to reduce molybdenum into a less toxic form and to grow on glyphosate is novel and makes the bacterium an important instrument for bioremediation of these pollutants.

Sites contaminated with both heavy metals and organic xenobiotic pollutants warrants the effective use of either a multitude of bacterial degraders or bacteria having the capacity to detoxify numerous toxicants simultaneously. A molybdenum-reducing bacterium with the capacity to degrade phenolics is reported. Molybdenum (sodium molybdate) reduction was optimum between pH 6.0 and 7.0 and between 20 and 30 degrees C. The most suitable electron donor was glucose. A narrow range of phosphate concentrations between 5.0 and 7.5 mM was required for optimal reduction, while molybdate between 20 and 30 mM were needed for optimal reduction. The scanning absorption spectrum of the molybdenum blue produced indicated that Mo-blue is a reduced phosphomolybdate. Molybdenum reduction was inhibited by the heavy metals mercury, silver and chromium. Biochemical analysis identified the bacterium as Pseudomonas putida strain Amr-12. Phenol and phenolics cannot support molybdenum reduction. However, the bacterium was able to grow on the phenolic compounds (phenol and catechol) with observable lag periods. Maximum growth on phenol and catechol occurred around the concentrations of 600 mg.L-1. The ability of this bacterium to detoxify molybdenum and grown on toxic phenolic makes this bacterium an important tool for bioremediation.