Disentangling\nthe Regulatory Response of Agrobacterium tumefaciens CHLDO to Glyphosate for\nEngineering Whole-Cell Phosphonate Biosensors

Phosphonates (PHTs),\norganic compounds with a stable\nC–P\nbond, are widely distributed in nature. Glyphosate (GP), a synthetic\nPHT, is extensively used in agriculture and has been linked to various\nhuman health issues and environmental damage. Given the prevalence\nof GP, developing cost-effective, on-site methods for GP detection\nis key for assessing pollution and reducing exposure risks. We adopted Agrobacterium tumefaciens CHLDO, a natural GP degrader,\nas a host and the source of genetic parts for constructing PHT biosensors.\nIn this bacterial species, the <i>phn</i> gene cluster,\nencoding the C–P lyase pathway, is regulated by the PhnF transcriptional\nrepressor. We selected the <i>phnG</i> promoter, which displays\na dose-dependent response to GP, to build a set of whole-cell biosensors.\nThrough stepwise genetic optimization of the transcriptional cascade,\nwe created a whole-cell biosensor capable of detecting GP in the 0.25–50\nμM range in various samples, including soil and water.