Engineering hydrolases by growth-based selections

Hydrolases are enzymes that split chemical bonds using water. They are useful in industry because they are easy to make and need no cofactors, for example in detergents, but many work too slowly, accept only limited substrates or are unstable.

Directed evolution can improve them through repeated cycles of generating variants, finding the best performers and amplifying them. Screening variants one by one is slow, so the thesis examines growth-based selection as a way to engineer hydrolases. In these methods, the enzyme's activity determines whether its bacterial host survives, mimicking natural selection in the laboratory; they are simple, need no special equipment and can test whole populations at once. The approach was used to evolve hydrolases for amino acid synthesis, plastic degradation and organofluorine breakdown.