title: Comparison of chromium III and VI toxicities in water using sulfur-oxidizing bacterial bioassays.
abstract: The toxicities of Cr (III) and Cr (VI) in water were evaluated using sulfur-oxidizing bacterial (SOB) bioassays both in batch and fed-batch conditions. Two days were enough for a quick buildup of SOB consortium in the master culture reactor (MCR). At concentrations up to 100 mg L(-1), Cr (III) was found to be nontoxic in both conditions, while Cr (VI) at very low concentrations (0.1-2 mg L(-1)) was very toxic to the SOB. Literature review suggested that the nontoxic nature of Cr (III) might be due to the absence of the iron uptake pathway in Acidithiobacillus caldus (the predominant bacteria in our reactors), which is required for Cr (III) uptake. The 2-h median effective concentration (EC50) values obtained for Cr (VI) in the batch and fed-batch tests were 2.7 mg L(-1) and 1.5 mg L(-1), respectively.
authors.affiliation: Department of Biological Environment, Kangwon National University, Gangwon-do, South Korea.
authors.forename: Naveed Ahmed
authors.initials: NA
authors.lastname: Qambrani
authors.affiliation: Department of Biological Environment, Kangwon National University, Gangwon-do, South Korea.
authors.forename: Ji-Hoon
authors.initials: JH
authors.lastname: Hwang
authors.affiliation: Department of Biological Environment, Kangwon National University, Gangwon-do, South Korea. Electronic address: ohsangeun@kangwon.ac.kr.
authors.forename: Sang-Eun
authors.initials: SE
authors.lastname: Oh
mesh_terms: D042763:Acidithiobacillus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D001681:Biological Assay; D002712:Chlorides / Q000737:chemistry / Q000633:toxicity*; D002857:Chromium / Q000737:chemistry / Q000633:toxicity*; D017608:Chromium Compounds / Q000737:chemistry / Q000633:toxicity*; D004784:Environmental Monitoring / Q000379:methods*; D007501:Iron / Q000378:metabolism; D010084:Oxidation-Reduction; D013455:Sulfur / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity*
chemical_list: D002712:Chlorides; D017608:Chromium Compounds; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion; D013455:Sulfur; D007501:Iron; C022990:chromic chloride
keywords: Bioassays; Cr (III) and Cr (VI) toxicity; Mechanism of action; SOB-biosensor; Sulfur-oxidizing bacteria