Initial Steps in the Degradation of Phosphinothricin (Glufosinate) by Soil Bacteria

Abstract

Three hundred bacterial isolates from soil were tested for resistance against phosphinothricin [PPT; DL-homoalanin-4-yl(methyl)phosphinic acid], the active ingredient of the herbicide BASTA. Eight resistant bacterial strains and Escherichia coli were analyzed for PPT-transforming activities. At least three different enzymatic reactions could be detected in cell extracts. In six strains an acetyltransferase was active, synthesizing N-acetyl-PPT in the presence of PPT and acetyl coenzyme A. All strains could degrade PPT to its corresponding 2-oxoacid {2-oxo-4-[(hydroxy)(methyl)phosphinoyl] butyric acid} by transamination. Rhodococcus sp., the only tested strain that was able to utilize PPT as a sole source of nitrogen, formed 2oxo-4[(hydroxy)(methyl)phosphinoyl]butyric acid by oxidative deamination. This enzymatic activity was inducible by L-glutamic acid or PPT itself but not in the presence of NH4'. D-PPT transformation was not detectable in any of the investigated strains.

In vivo utilization of N‐(phosphonomethyl)‐anilines and related substances by Pseudomonas spec. GS

“…Changes in one of these molecular regions will decrease the utilization capacity of Pseudomonas towards these phosphonates as source for phosphorus. This hypothesis is confirmed by the reports of TEBBE and REBER (1988) and BARTSCH and TEBBE (1989) who demonstrated that phosphinothricin is metabolized by soil bacteria but may not be utilized as source of phosphorus. But in order to get a clear understanding of the enzymological cleavage of C-P-bond in Pseudomonas the metabolism of phosphonates must be investigated with purified enzymes.…”

Evolution in agriculture: the application of evolutionary approaches to the management of biotic interactions in agro‐ecosystems

“…Thus, one offset to the problem of enhanced biodegradation of soilapplied pesticides has been the discovery of many novel gene/enzyme systems responsible for degrading the various chemistries among the soil microflora. Some of these gene/enzyme systems have subsequently proven extremely useful in the development of transgenic herbicide-resistant crops (Bartsch and Tebbe 1989;Wehrmann et al 1996;Castle et al 2004). Others have been used in the development of bioremediation agents for the clean-up of contaminated environments (Sutherland et al 2004;Scott et al 2008;Russell et al 2011).…”

Bacterial community composition in the rhizosphere of a transgenic, herbicide-resistant maize (Zea mays) and comparison to its non-transgenic cultivar Bosphore

“…It is phytotoxic by interfering with photophosphorylation through accumulation of intracellular NH þ 4 [3,4] but its toxicity to mammals is rather low [5,6]. Some microbial activities, including growth of several soil bacteria [7] and of Esche-richia coli [8] or the nodulation of Lucerne (alfalfa) roots by Sinorhizobium meliloti [9] are sensitive to concentrations of 1 mM or less under laboratory conditions. In contrast, it has been reported that many bacteria in surface or subsurface soil are resistant to glufosinate [7,8,10,11].…”

“…Some microbial activities, including growth of several soil bacteria [7] and of Esche-richia coli [8] or the nodulation of Lucerne (alfalfa) roots by Sinorhizobium meliloti [9] are sensitive to concentrations of 1 mM or less under laboratory conditions. In contrast, it has been reported that many bacteria in surface or subsurface soil are resistant to glufosinate [7,8,10,11]. In soil, glufosinate is quickly degraded by deamination and decarboxylation to a non-toxic intermediate, which is further mineralised [12^15].…”