Degradation of Phosphonate Herbicide Glyphosate by Acinetobacter lwoffü HN401

An Acinetobacter lwoffü HN401 isolated from heavily polluted urban streams metabolized glyphosate as well as aminomethylphosphonate (AMPn) as source of phosphorus. The strain also exhibited similar growth yields in media containing glyphosate, AMPn, or orthophosphate. The HN401 grown in the 1 mM glyphosate followed by phosphate-free minimal medium treatment without glyphosate showed a growth curve virtually indistinguishable from that of cells grown in 0.1 mM glyphosate. The HN401 completely depleted the orthophosphate from the medium before it started to take up glyphosate. But we could not detect the phosphate from product(s) of glyphosate degradaton. The HN401 transported nearly 85% of the glyphosate in the medium into the cells within 10 min and could not transport glyphosate even in the presence of 0.1 mM [14C]glyphosate, while glyphosate uptake rate of the cells starved for 6 h increased noticeably. Thus, phosphorus deprivation in the medium may induce the system by which glyphosate is taken up.