Development of a whole cell biosensor for detection of 2, 4-diacetylphloroglucinol (DAPG) producing bacteria from grassland soil

Morten Lindqvist Hansen, Zhiming He, Mario Wibowo, Lars Jelsbak*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Fluorescent Pseudomonas spp. producing the antibiotic 2,4-diacetylphloroglucinol (DAPG) are ecologically important in the rhizosphere as they can control phytopathogens and contribute to disease suppressiveness. DAPG can also trigger a systemic resistance response in plants and stimulate root exudation and branching as well as induce plant-beneficial activities in other rhizobacteria. While studies of DAPG-producing Pseudomonas have predominantly focused on rhizosphere niches, the ecological role of DAPG as well as the distribution and dynamics of DAPG-producing bacteria remains less well understood for other environments such as bulk soil and grassland, where the level of DAPG producers are predicted to be low. Here, we construct a whole cell biosensor for detection of DAPG and DAPG-producing bacteria from environmental samples.The constructed biosensor contains a phlF response module and either lacZ or lux genes as output modules assembled on a pSEVA plasmid backbone for easy transfer to different host species and to enable easy future genetic modifications. We show that the sensor is highly specific toward DAPG, with a sensitivity in the low nanomolar range (>20 nM). This sensitivity is comparable to the DAPG levels identified in rhizosphere samples by chemical analysis. The biosensor enables guided isolation of DAPG-producing Pseudomonas Using the biosensor, we probed the same grassland soil sampling site to isolate genetically related DAPG-producing Pseudomonas kilonensis strains over a period of 12 months. Next, we used the biosensor to determine the frequency of DAPG-producing Pseudomonas within three different grassland soil sites and show that DAPG producers can constitute part of the Pseudomonas population in the range of 0.35-17% at these sites. Finally, we show that the biosensor enables detection of DAPG produced by non-Pseudomonas species. Our studies show that a whole-cell biosensor for DAPG detection can facilitate isolation of bacteria that produce this important secondary metabolite and provide insight into the population dynamics of DAPG producers in natural grassland soil.
Original languageEnglish
JournalApplied and Environmental Microbiology
Volume87
Issue number3
ISSN0099-2240
DOIs
Publication statusPublished - 2021

Keywords

  • Secondary metabolites
  • Pseudomonas
  • DAPG
  • Synthetic biology
  • Biocontrol

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