Isolation and Characterization of a Mutant of Arthrobacter sp. Strain GLP-1 Which Utilizes the Herbicide Glyphosate as Its Sole Source of Phosphorus and Nitrogen

Abstract

Arthrobacter sp. strain GLP-1, grown on glucose as a carbon source, utilizes the herbicide glyphosate [ N -(phosphonomethyl)glycine] as its sole source of phosphorus as well as its sole source of nitrogen. The mutant strain GLP-1/Nit-1 utilizes glyphosate as its sole source of nitrogen as well. In strain GLP-1, P i was a potent competitive inhibitor of glyphosate uptake ( K i , 24 μM), while the affinity of P i for the uptake system of strain GLP-1/Nit-1 was reduced by 2 orders of magnitude ( K i , 2.3 mM). It is concluded that the inability of strain GLP-1 to utilize glyphosate as a source of nitrogen is due to the stringent control of glyphosate uptake by excess phosphate released during the degradation of the herbicide.