Engineering reduced-genome strains of Pseudomonas putida for product valorization

Environmental bacteria, such as strains of the genus Pseudomonas, constitute ideal starting points for the design of robust cell factories. These microorganisms are pre-endowed with a number of metabolic and stress-endurance traits that make them optimal for the needs of contemporary biotechnology. Significant technological advances in recent times opened new avenues for metabolic engineering of Pseudomonas species. Against this background, in this chapter we discuss the current engineering efforts aimed at launching the Gram-negative soil bacterium P. putida as a chassis for product valorization and refinement. We focus on the use of reducedgenome strains of P. putida, endowed with enhanced physiological characteristics (e.g., increased availability of ATP and NADPH, the energy and redox currencies of the cell), for the construction of bacterial cell factories that can be used across a range of operating conditions. Cutting-edge synthetic biology approaches for genome engineering, which significantly reduced the time needed for the construction of such reduced-genome variants of P. putida, are likewise discussed. We conclude the chapter by discussing future trends and bottlenecks toward the establishment of a minimal-genome chassis based on P. putida.