Identification of degradation routes of metamitron in soil microcosms using13C-isotope labeling.
Metamitron is one of the most commonly used herbicide in sugar beet and flower bulb cultures. Numerous laboratory and field studies on sorption and degradation of metamitron were performed. Detailed biodegradation studies in soil using13C-isotope labeling are still missing. Therefore, we aimed at providing a detailed turnover mass balance of13C6-metamitron in soil microcosms over 80 days. In the biotic system, metamitron mineralized rapidly, and13CO2finally constituted 60% of the initial13C6-metamitron equivalents. In abiotic control experiments CO2rose to only 7.4% of the initial13C6-metamitron equivalents. The13C label from13C6-metamitron was incorporated into microbial amino acids that were ultimately stabilized in the soil organic matter forming presumably harmless biogenic residues. Finally,13C label from13C6-metamitron was distributed between the13CO2and the13C-biogenic residues indicating nearly complete biodegradation. The parallel increase of13C-alanine,13C-glutamate and13CO2indicates that metamitron was initially biodegraded via the desamino-metamitron route suggesting its relevance in the growth metabolism. In later phases of biodegradation, the "Rhodococcus route" was indicated by the low13CO2evolution and the high relevance of the pyruvate pathway, which aims at biomolecule synthesis and seems to be related to starvation. This is a first report on the detailed degradation route of metamitron in soil.
Helmholtz-Centre for Environmental Research - UFZ, Department of Environmental Biotechnology, Permoserstr. 15, 04318 Leipzig, Germany; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, PR China.
Shizong
S
Wang
Helmholtz-Centre for Environmental Research - UFZ, Department of Environmental Biotechnology, Permoserstr. 15, 04318 Leipzig, Germany.
Anja
A
Miltner
Helmholtz-Centre for Environmental Research - UFZ, Department of Environmental Biotechnology, Permoserstr. 15, 04318 Leipzig, Germany; RWTH Aachen University, Institute for Environmental Research, Worringerweg 1, 52074 Aachen, Germany. Electronic address: karolina.nowak@ufz.de.
Karolina M
KM
Nowak
D000383:Agriculture; D027461:Beta vulgaris; D001673:Biodegradation, Environmental; D004784:Environmental Monitoring; D005858:Germany; D006540:Herbicides / Q000737:chemistry*; D007553:Isotope Labeling; D018517:Plant Roots; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis / Q000378:metabolism*; D014227:Triazines / Q000378:metabolism*
D006540:Herbicides; D012987:Soil; D012989:Soil Pollutants; D014227:Triazines
Amino acid; Biogenic residue; Herbicide; Metabolization; Non-extractable residue