How is adaptive laboratory evolution used for strain improvement?

Adaptive laboratory evolution (ALE) evolves improved strains through prolonged cultivation under selective pressure. Process involves: defining selection conditions (stressor, substrate limitation, growth rate), continuous culture (chemostat) or serial transfer (batch), extended cultivation (weeks to months, hundreds of generations), isolating evolved clones, characterizing improvements, and identifying mutations through whole-genome sequencing. Applications include: stress tolerance (temperature, solvents, product toxicity), substrate utilization (novel carbon sources), growth rate improvement, and antibiotic resistance studies. Advantages over rational engineering: discovers non-obvious solutions, achieves complex multigenic adaptations. Limitations: time-consuming, may acquire unwanted mutations, improvements may not transfer to different conditions. Combining ALE with reverse engineering enables rational application of beneficial mutations.