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Query: UMLS:C0038187 (
starvation
)
24,951
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
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
C
6
-metamitron in soil microcosms over 80 days. In the biotic system, metamitron mineralized rapidly, and
13
CO
2
finally constituted 60% of the initial
13
C
6
-metamitron equivalents. In abiotic control experiments CO
2
rose to only 7.4% of the initial
13
C
6
-metamitron equivalents. The
13
C label from
13
C
6
-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
C
6
-metamitron was distributed between the
13
CO
2
and the
13
C-biogenic residues indicating nearly complete biodegradation. The parallel increase of
13
C-alanine,
13
C-glutamate and
13
CO
2
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
CO
2
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.
...
PMID:Identification of degradation routes of metamitron in soil microcosms using
13
C-isotope labeling. 2782 63
Metamitron
and its main metabolite desamino-metamitron are frequently detected in surface waters. To date, there are no studies targeting metamitron degradation in water-sediment systems. Therefore, the aim of this study was to trace the fate of metamitron in a water-sediment system using
13
C-isotope labeling. Mineralization of metamitron was high and accounted for 49% of
13
C
6
-metamitron equivalents at the end. In contrast, only 8.7% of
13
C
6
-metamitron equivalents were mineralized in the water only system demonstrating the key role of sediment for biodegradation.
Metamitron
disappeared from the water on day 40 and was completely removed from the sediment on day 80. This agrochemical was utilized as carbon source by microorganisms as shown by the incorporation of the
13
C label into microbial amino acids and finally into biogenic residues. The latter amounted to 24% of
13
C
6
-metamitron equivalents at the end. However, 17% of
13
C
6
-metamitron equivalents were detected in xenobiotic non-extractable residues (NER) with a release potential and delayed risk for the environment.
Metamitron
was degraded via two pathways, initially via 4-(dimethylimino)-3-methyl-6-phenyl-1,2,4-triazin-5(4H)-one, which might be related to growth, and later via desamino-metamitron, which can be attributed to
starvation
.
...
PMID:Transformation of metamitron in water-sediment systems: Detailed insight into the biodegradation processes. 2783 59
