Laccase-catalyzed oxidation of iodide and formation of organically bound iodine in soils.

Laccase oxidizes iodide to molecular iodine or hypoiodous acid, both of which are easily incorporated into natural soil organic matter. In this study, iodide sorption and laccase activity in 2 types of Japanese soil were determined under various experimental conditions to evaluate possible involvement of this enzyme in the sorption of iodide. Batch sorption experiment using radioactive iodide tracer ((125)I(-)) revealed that the sorption was significantly inhibited by autoclaving (121 °C, 40 min), heat treatment (80 and 100 °C, 10 min), γ-irradiation (30 kGy), N(2) gas flushing, and addition of reducing agents and general laccase inhibitors (KCN and NaN(3)). Interestingly, very similar tendency of inhibition was observed in soil laccase activity, which was determined using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) as a substrate. The partition coefficient (K(d): mL g(-1)) for iodide and specific activity of laccase in soils (Unit g(-1)) showed significant positive correlation in both soil samples. Addition of a bacterial laccase with an iodide-oxidizing activity to the soils strongly enhanced the sorption of iodide. Furthermore, the enzyme addition partially restored iodide sorption capacity of the autoclaved soil samples. These results suggest that microbial laccase is involved in iodide sorption on soils through the oxidation of iodide.

[1]  P. Baldrian,et al.  Laccase activity in soils: considerations for the measurement of enzyme activity. , 2012, Chemosphere.

[2]  K. Schwehr,et al.  Bacterial production of organic acids enhances H2O2-dependent iodide oxidation. , 2012, Environmental science & technology.

[3]  H. Yoshikawa,et al.  Iodide Oxidation by a Novel Multicopper Oxidase from the Alphaproteobacterium Strain Q-1 , 2012, Applied and Environmental Microbiology.

[4]  K. Schwehr,et al.  Is soil natural organic matter a sink or source for mobile radioiodine (129I) at the Savannah River Site , 2011 .

[5]  K. Schwehr,et al.  Factors controlling mobility of 127I and 129I species in an acidic groundwater plume at the Savannah River Site. , 2011, The Science of the total environment.

[6]  K. Schwehr,et al.  Concentration-dependent mobility, retardation, and speciation of iodine in surface sediment from the Savannah River Site. , 2011, Environmental science & technology.

[7]  Y. Terada,et al.  Formation of organic iodine supplied as iodide in a soil-water system in Chiba, Japan. , 2011, Environmental science & technology.

[8]  M. Nakano,et al.  Inorganic iodine incorporation into soil organic matter: evidence from iodine K-edge X-ray absorption near-edge structure. , 2010, Journal of environmental radioactivity.

[9]  R. Sinsabaugh.  Phenol oxidase, peroxidase and organic matter dynamics of soil , 2010 .

[10]  K. Schwehr,et al.  Organo-iodine formation in soils and aquifer sediments at ambient concentrations. , 2009, Environmental science & technology.

[11]  G. Luther,et al.  The kinetics of iodide oxidation by the manganese oxide mineral birnessite , 2009 .

[12]  S. Criquet,et al.  ABTS assay of phenol oxidase activity in soil. , 2007, Journal of microbiological methods.

[13]  M. Schlegel,et al.  Molecular environment of iodine in naturally iodinated humic substances: Insight from X-ray absorption spectroscopy , 2006 .

[14]  S. Allison.  Soil minerals and humic acids alter enzyme stability: implications for ecosystem processes , 2006 .

[15]  T. Uruga,et al.  Speciation of iodine in solid environmental samples by iodine K-edge XANES: application to soils and ferromanganese oxides. , 2006, The Science of the total environment.

[16]  Timothy Y James,et al.  Phylogenetic comparison and classification of laccase and related multicopper oxidase protein sequences , 2006, The FEBS journal.

[17]  M. Nakano,et al.  Redox reaction of iodine in paddy soil investigated by field observation and the I K-Edge XANES fingerprinting method. , 2006, Journal of environmental radioactivity.

[18]  Y. Kamagata,et al.  Isolation of Iodide-Oxidizing Bacteria from Iodide-Rich Natural Gas Brines and Seawaters , 2005, Microbial Ecology.

[19]  H. Claus.  Laccases and their occurrence in prokaryotes , 2003, Archives of Microbiology.

[20]  A. Aldahan,et al.  129I from the nuclear reprocessing facilities traced in precipitation and runoff in northern Europe. , 2001, Environmental science & technology.

[21]  K. Sakamoto,et al.  Turnover time of microbial biomass carbon in Japanese upland soils with different textures , 2000 .

[22]  F. Hardeman,et al.  The true absorption of 131I, and its transfer to milk in cows given different stable iodine diets , 2000 .

[23]  D. Schink,et al.  Atmospheric dispersal of 129iodine from nuclear fuel reprocessing facilities , 1999 .

[24]  Y. Muramatsu,et al.  Effects of Microorganisms on the Fate of Iodine in the Soil Environment , 1999 .

[25]  G. A. Bird,et al.  Distribution coefficients, Kds, for iodide in Canadian Shield Lake sediments under oxic and anoxic conditions , 1997 .

[26]  P. A. Smith,et al.  Linearity of iodine sorption and sorption capacities for seven soils , 1996 .

[27]  Feng Xu.  Catalysis of novel enzymatic iodide oxidation by fungal laccase , 1996 .

[28]  M. Fukui,et al.  Factors affecting interaction of radioiodide and iodate species with soil , 1996 .

[29]  康行 村松,et al.  日本の土壌63試料に対するI-とIO3-の吸着 , 1995 .

[30]  J. Cullen,et al.  Redox Chemistry of Iodine in Seawater: Frontier Molecular Orbital Theory Considerations , 1995 .

[31]  J. J. Morgan,et al.  Aquatic Chemistry: Interfacial and Interspecies Processes , 1995 .

[32]  吉田 聡,et al.  Adsorption of I- and IO3- onto 63 Japanese Soils. , 1995 .

[33]  R. Martens,et al.  The contribution of microbial biomass to the adsorption of radioiodide in soils , 1992 .

[34]  L. Carlsen,et al.  Enzymatically Controlled Iodination Reactions in the Terrestrial Environment , 1991 .

[35]  B. Hetzel,et al.  A review of experimental studies of iodine deficiency during fetal development. , 1989, The Journal of nutrition.

[36]  R. Fuge,et al.  The geochemistry of iodine — a review , 1986, Environmental geochemistry and health.

[37]  R. Burns.  Enzyme activity in soil: Location and a possible role in microbial ecology , 1982 .

[38]  Chilean Iodine.  Geochemistry of Iodine , 1956 .