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Title (Primary) Formation and fate of bound residues from microbial biomass during 2,4-D degradation in soil
Author Nowak, K.M.; Miltner, A.; Gehre, M.; Schäffer, A.; Kästner, M.
Journal Environmental Science & Technology
Year 2011
Department ISOBIO; UBT
Volume 45
Issue 3
Page From 999
Page To 1006
Language englisch
Abstract During organic contaminant degradation in soil, bound or nonextractable residues (NER) are formed. Part of these residues may be biogenic, because degrading microorganisms assimilate carbon derived from the pollutant and mineralized CO2 to form cellular components for example, [fatty acids (FA) and amino acids (AA)], which are subsequently stabilized within soil organic matter (SOM). We investigated the formation and fate of FA and AA from biodegradation of 13C6-2,4-D in soil and the incorporation of the 13C-label into living biomass via 13CO2 fixation. After 64 days of incubation, 13C-AA in SOM indicated that 44% of the initially applied 13C6-2,4-D equivalents had been converted to microbial biomass and finally to biogenic residues. The intermediate maximum of 13C-FA in SOM indicated a 20% conversion of 13C6-2,4-D to biomass, but 13C-FA decreased to 50% of that value whereas 13C-AA in the SOM remained stable. We provide the first evidence that nearly all bound residues from 2,4-D are biogenic, containing natural microbial residues stabilized in SOM. Because of biogenic residue formation, the potential risk of bound residues from readily metabolized xenobiotics in soils is highly overestimated. Hence, the formation of biogenic residues must be considered in general when performing mass balances of pollutant biodegradation in soils.
Persistent UFZ Identifier
Nowak, K.M., Miltner, A., Gehre, M., Schäffer, A., Kästner, M. (2011):
Formation and fate of bound residues from microbial biomass during 2,4-D degradation in soil
Environ. Sci. Technol. 45 (3), 999 - 1006