Using Synthetic Biology for Determining Biological Controls on Marine Carbon Sequestration

A key flux in the marine carbon cycle is the transfer of photosynthesized organic matter from the surface ocean to the sea floor, which sequesters it in the deep ocean. This sequestration is mediated by complex biological processes that are regulated by bacterial quorum sensing. To understand the marine carbon flux, quantifying the bioavailable concentrations of autoinducer compounds that drive quorum sensing is imperative. Since current analytical methods fail to report these concentrations, we describe the construction and testing of bacterial biosensors that can persist in a marine matrix. These sensors detect acyl homoserine lactones and respond with a gas output, overcoming the limitation of fluorescence-based biosensors in marine matrices. With our biosensors, we can detect concentrations of acyl homoserine lactones in the nM range, which is biologically and environmentally significant. These new tools will enable measurements that provide quantitative insight into the biological controls of the marine carbon cycle and inform models of marine response to anthropogenic climate change.