Identification of degradation routes of metamitron in soil microcosms using 13C-isotope labeling. (January 2017)

• Record Type: Journal Article
• Authors: Wang, Shizong; Miltner, Anja; Nowak, Karolina M.
• Is Part Of: Environmental pollution. Volume 220:Part B(2017)
• Page Start: 927
• Page End: 935
• Publication Date: 2017-01
• Subjects: Herbicide -- Metabolization -- Non-extractable residue -- Biogenic residue -- Amino acid; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2016.10.078
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: 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 using 13 C-isotope labeling are still missing. Therefore, we aimed at providing a detailed turnover mass balance of 13 C6 -metamitron in soil microcosms over 80 days. In the biotic system, metamitron mineralized rapidly, and 13 CO2 finally constituted 60% of the initial 13 C6 -metamitron equivalents. In abiotic control experiments CO2 rose to only 7.4% of the initial 13 C6 -metamitron equivalents. The 13 C label from 13 C6 -metamitron was incorporated into microbial amino acids that were ultimately stabilized in the soil organic matter forming presumably harmless biogenic residues. Finally, 13 C label from 13 C6 -metamitron was distributed between the 13 CO2 and the 13 C-biogenic residues indicating nearly complete biodegradation. The parallel increase of 13 C-alanine, 13 C-glutamate and 13 CO2 indicates 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 low 13 CO2 evolution 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. Graphical abstract: Highlights: First detailed report on 13 C6 -metamitron turnover mass balance in soil. 13 C6 -metamitron was ultimately degraded to CO2 and biogenic residues. Metamitron was biodegraded via two routes: desamino-metamitron and "Rhodococcus". Desamino-metamitron route was assigned to growth metabolism. "Rhodococcus" route was related to starvation metabolism. Abstract : 13 C6 -metamitron was completely biodegraded in soil and via two routes: initially via the desamino-metamitron related to growth and later via the " Rhodococcus " assigned to starvation.