Sensing and Sensitivity; From the quorum to the single bacterial cell

Genetic engineering has enabled the development of a range of sensors for detecting transcription of genes of interest in bacteria. These have found particular use in detecting quorum sensing signalling compounds involved in multicellular behaviour of bacterial cells and for detection of specific analyses of interest, such as antibiotics. Sensors have been used for assays utilising chromophores, fluorophores and bioluminescence, although because of limited sensitivity in terms of detection these have been applied mainly to large cell populations.
Green fluorescent protein (GFP) and derivatives are more sensitive for use in analysis of single isolated bacterial cells with significant potential for investigating the genetic heterogeneity that may develop in cell populations derived from the same clone. Laser tweezing and microfluidics methods for isolating and recombining individual cells are being developed and used in the EU-funded MaCuMBA project at HWU for culturing biotechnological-useful cells from the marine environment. The potential and limitations of using a quorum sensing activated GFP sensor in this format are currently under investigation. Demonstration of the utility of the cell isolation process includes testing for recovery of marine bacterial cells from dormancy using growth (‘resuscitation’) factors isolated during the MaCuMBA project.