An Optical Microbial Biosensor Based on Whole Cell of Acidithiobacillus thiooxidans for Hydrogen Sulfide Determination

Abstract

Due to its corrosive and highly toxic character, the generation of hydrogen sulfide is a serious problem for the environment, human health, and the industry. This paper reported a new and simple methodology for aqueous hydrogen sulfide determination through the development of an optical microbial biosensor. The principle of detection was based on the aerobic and chemolithotrophic metabolism of Acidithiobacillus thiooxidans bacterial cells. Under low oxygen concentration and acidic conditions A. thiooxidans can rapidly oxidize H₂S to elemental sulfur. The biochemical formation of elemental sulfur can be spectrophotometrically detected and the increase in absorbance at 620 nm exhibited a linear relationship to an H₂S concentration up to 100 mg.L^-1. The parameters concerning the analytical performance of the biosensor such as cell harvesting time and pH influence were measured and optimized through the optical absorption value. The biosensor was selective to H₂S with no important disturbance by tested species except thiosulfate ion (11.5% error). Biosensor response expressed good repeatability (RSD = 4.46 %) and reproducibility (RSD = 4.66 %). The low cost of cell cultivation and the absence of the immobilization step make feasible the optic biosensor application.