Effects of dissolved low molecular weight organic acids on oxidation of ferrous iron by Acidithiobacillus ferrooxidans.
A few researchers have reported on work concerning bioleaching of heavy-metal-contaminated soil using Acidithiobacillus ferrooxidans, since this acidophile is sensitive to dissolved low molecular weight (LMW) organic acids. Iron oxidation by A. ferrooxidans R2 as well as growth on ferrous iron was inhibited by a variety of dissolved LMW organic acids. Growth experiments with ferrous iron as an oxidant showed that the inhibition capability sequence was formic acid>acetic acid>propionic acid>oxalic acid>malic acid>citric acid. The concentrations that R2 might tolerate were formic acid 0.1mmolL(-1) (2mmolkg(-1)soil), acetic and propionic acids 0.4mmolL(-1) (8mmolkg(-1)soil), oxalic acid 2.0mmolL(-1) (40mmolkg(-1)soil), malic acid 20mmolL(-1) (400mmolkg(-1)soil), citric acid 40mmolL(-1) (800mmolkg(-1)soil), respectively. Although R2 was sensitive to organic acids, the concentrations of LMW organic acids in the contaminated soils were rather lower than the tolerable levels. Hence, it is feasible that R2 might be used for bioleaching of soils contaminated with metals or metals coupled with organic compounds because of the higher concentrations of LMW organic acids to which R2 is tolerant.
Ren
Wan-Xia
WX
Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, People's Republic of China.
Li
Pei-Jun
PJ
Zheng
Le
L
Fan
Shu-Xiu
SX
Verhozina
V A
VA
D013856:Acidithiobacillus thiooxidans / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D000144:Acids, Acyclic / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000737:chemistry; D005296:Ferrous Compounds / Q000737:chemistry*; D007202:Indicators and Reagents; D019216:Metals, Heavy / Q000032:analysis; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction; D012336:RNA, Ribosomal, 16S / Q000737:chemistry; D012015:Reference Standards; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012988:Soil Microbiology
D000144:Acids, Acyclic; D005296:Ferrous Compounds; D007202:Indicators and Reagents; D019216:Metals, Heavy; D012336:RNA, Ribosomal, 16S; D004247:DNA