Genetic programming of catalytic Pseudomonas putida biofilms for boosting biodegradation of haloalkanes

• Tunable biofilm formation and dispersal achieved in Pseudomonas putida.
• Tight expression of enzymes controlling cyclic diguanosine monophosphate levels.
• Catalytic biofilms of Pseudomonas putida displaying a high dehalogenase activity.
• Natural advantages of a hefty biocatalyst exploited in a novel, controllable setup.
• First report on the manipulation of synthetic morphology in whole-cell biocatalysis.

Bacterial biofilms outperform planktonic counterparts in whole-cell biocatalysis. The transition between planktonic and biofilm lifestyles of the platform strain Pseudomonas putida KT2440 is ruled by a regulatory network controlling the levels of the trigger signal cyclic di-GMP (c-di-GMP). This circumstance was exploited for designing a genetic device that over-runs the synthesis or degradation of c-di-GMP – thus making P. putida to form biofilms at user׳s will. For this purpose, the transcription of either yedQ (diguanylate cyclase) or yhjH (c-di-GMP phoshodiesterase) from Escherichia coli was artificially placed under the tight control of a cyclohexanone-responsive expression system. The resulting strain was subsequently endowed with a synthetic operon and tested for 1-chlorobutane biodegradation. Upon addition of cyclohexanone to the culture medium, the thereby designed P. putida cells formed biofilms displaying high dehalogenase activity. These results show that the morphologies and physical forms of whole-cell biocatalysts can be genetically programmed while purposely designing their biochemical activity.