Distribution of glyphosate and methylphosphonate catabolism systems in soil bacteria Ochrobactrum anthropi and Achromobacter sp

Abstract

Bacterial strains capable of utilizing methylphosphonic acid (MP) or glyphosate (GP) as the sole sources of phosphorus were isolated from soils contaminated with these organophosphonates. The strains isolated from MP-contaminated soils grew on MP and failed to grow on GP. One group of the isolates from GP-contaminated soils grew only on MP, while the other one grew on MP and GP. Strains Achromobacter sp. MPS 12 (VKM B-2694), MP degraders group, and Ochrobactrum anthropi GPK 3 (VKM B-2554D), GP degraders group, demonstrated the best degradative capabilities towards MP and GP, respectively, and were studied for the distribution of their organophosphonate catabolism systems. In Achromobacter sp. MPS 12, degradation of MP was catalyzed by C-P lyase incapable of degrading GP (C-P lyase I). Adaptation to growth on GP yielded the strain Achromobacter sp. MPS 12A, which retained its ability to degrade MP via C-P lyase I and was capable of degrading GP with formation of sarcosine, thus suggesting the involvement of a GP-specific C-P lyase II. O. anthropi GPK 3 also degraded MP via C-P lyase I, but degradation of GP in it was initiated by glyphosate oxidoreductase, which was followed by product transformation via the phosphonatase pathway.

Utilization of Glyphosate as Phosphate Source: Biochemistry and Genetics of Bacterial Carbon-Phosphorus Lyase

“…strain MPS contained detectable amounts of glyphosate following growth of the species in the presence of glyphosate, providing evidence for the existence of a transport mechanism for the compound. Both of these strains were isolated from phosphonatecontaminated soil (21).…”

“…This conclusion was based on the observation that AMPA could be removed from cell extracts by the addition of pyruvate, which was converted to alanine, indicating the presence of an aminotransferase activity. The remaining part of AMPA subsequently was expected to be phosphonoformaldehyde, for which an enzymatic cleavage activity has not been identified (21). Perhaps the presence of glyphosate rather altered the uptake system for glyphosate and simultaneously altered the properties for the uptake of other phosphonates as well.…”

“…Additionally, methylphosphonate growth-proficient Achromobacter sp. strain MPS12 could be adapted to growth with glyphosate as the sole P i source, apparently by synthesizing a second glyphosate-specific C-P lyase, and O. anthropi strain GPK3 has been postulated to contain two C-P lyases, one specific for methylphosphonate and the other specific for glyphosate (21). The C-P lyase-encoding genes and their organization in a number of organisms are described in detail below.…”

“…Alternatively, phosphonoacetaldehyde is oxidized to phosphonoacetate catalyzed by phosphonoacetaldehyde dehydrogenase (59). Also, hydrolytic activities for phosphonoacetate (59,(86)(87)(88)(89)(90) as well as for phosphonopyruvate (91) have been described, and a hydrolytic activity for phosphonoformaldehyde has been suggested (21). Phosphonopyruvate in turn may be formed by the activities of phosphoenolpyruvate phosphomutase or phosphoalanine:2-oxoglutarate transaminase (91)(92)(93).…”

Scientific Opinion on application (EFSA‐GMO‐NL‐2010‐87) for the placing on the market of genetically modified herbicide tolerant oilseed rape GT73 for food containing or consisting of, and food produced from or containing ingredients produced from, oilseed rape GT73 (with the exception of refined oil and food additives) under Regulation (EC) No 1829/2003 from Monsanto

“…strain CP4) and O. anthropi strain LBAA, respectively). As natural variants of such genes are already present in bacteria occurring in the environment, homologous recombination and acquisition of the recombinant genes by bacteria will not confer novel properties possibly providing selective advantages to members of the natural microbial communities (Cao et al, 2012;Fan et al, 2012;Sviridov et al, 2012). In environments frequently exposed to glyphosate, bacteria with resistance against this compound may be selected.…”