Abstract

PACHECO AGUILAR, Juan Ramiro; MALDONADO VEGA, María  and  PENA CABRIALES, Juan José. Sulfur metabolism in bacterial isolates from a constructed wetland used for treating tannery industrial wastewater. Rev. Int. Contam. Ambient [online]. 2012, vol.28, n.3, pp.195-201. ISSN 0188-4999.

Constructed wetlands are an alternative for the treatment of effluents where biological oxidation processes caused by the rhizosphere of plants and microorganisms present in situ, contribute to the removal of contaminants. In the present work, we characterized the sulfur (S) metabolism of ten bacteria belonging to the genera Acinetobacter,Alcaligenes, Ochrobactrum and Pseudomonas, which were isolated from a wetland constructed for the treatment of effluents with high organic matter content (biochemical oxygen demand: BOD₅ 1320 mg/L) and sulfides (54 mg/L) from the leather tanning industry. Biochemical assays indicate that all the isolates can use some sulfur species such as elemental sulfur (S⁰), thiosulfate (S₂O₆^2-) or sulfide (S^2-) as the sole source of S. We also found that strains of Pseudomonas genus were the most versatile base on the fact that they oxidize S^2- (2 mM) and S₂O₆^2- (4 mM) transforming them to S⁰ and tetrathionate (S₄O₆^2-), respectively, whereas Acinetobacter strains only oxidize S⁰ to S₂O₆^2-. We also found that the strains of the genera Alcaligenes and Ochrobactrum oxidize S₂O₆^2- (4 mM) to S₄O₆^2-. The activity of these microorganisms through the treatment system and the integration of their metabolism might actively participate in the removal of sulfur compounds.

Keywords : Oxidation; sulfide (S^2-); elemental sulfur (S⁰); thiosulfate (S₂O₆^2-); tetrathionate (S₄O₆^2-); Acinetobacter; Alcaligenes; Ochrobactrum; Pseudomonas.