RESEARCH SUMMARY

Our laboratory is committed to understanding how bacteria that inhabit natural niches sense and process multiple environmental signals into distinct responses –both at the level of single cells and as a community. Unlike laboratory settings, in which growth conditions can be controlled and changed one at a time, bacteria in the environment must perpetually make decisions between activating metabolic genes for available, frequently mixed C-sources and those for escaping or adapting to physicochemical stress.

Our preferred experimental system involves the strain KT2440 of the soil and plant root colonizer Pseudomonas putida bearing the plasmid pWW0, which allows growth on toluene and m-xylene as the only C and energy source. The biotechnological side of this biological question is the possibility of programming bacteria for deliberate environmental release, aimed at biodegradation of toxic pollutants or as biosensors for monitoring the presence of given chemicals.

Apart from understanding and developing such sensor or catalytic bacteria, their release requires the GMO to be endowed with a high degree of containment and predictability. In this line, our research takes on board the development of novel molecular tools for the genetic analysis and construction of soil microorganisms (mostly Pseudomonads) destined for the environment or as catalysis for selected biotransformations. We recently became active in the interface between synthetic biology and environmental microbiology as a source of new tools for addressing some outstanding environmental pollution problems. We are currently developing technologies for deep genetic engineering of P. putida and other environmental bacteria. These have allowed both a complete understanding of various catalytic and physiological processes and have opened up exciting opportunities for a radical genomic refactoring of the corresponding biological agents.

One of the outcomes involved the design of bacteria able to translate the presence of residues of explosives in soil (which can be traced by following the fate of 2,4 dinitrotoluene) into a luminescent signal. At the same time, we studied the logic programs that underlie many of the metabolic and regulatory networks that endow P. putida (and other bacteria) with the ability to endure harsh environmental conditions, and found most of them amenable to modelling with Boolean formalisms. Since digital circuits based on logic operations are the basis of computation, we recently began to develop a suite of basic, connectable Boolean gates using regulatory and metabolic components aimed at programming cells to behave in a predetermined way.