Choosing Low versus High Throughput

In this section, we will discuss the critical issues in deciding the balance between throughput and accuracy in the screen. A minimal screening requirement can be roughly estimated from the frequency of positive mutants found either in earlier rounds of directed evolution or from results reported in literature. The frequency of positive mutants for different enzymes and different properties varies, but is usually found in the range of about one out of 102 to 10s mutants (Table 4-2). However, it should be noted that the frequency of positive mutants will strongly depend on the fitness of the parent the property, and the strategy chosen to create the mutant library. 

Frequency of positive mutants (tested/positive) Evolved property / mutagenesis procedure / test Reference 

3xl0 5 (6.4xl04/2) Thermal and oxidative stability / PCR / screen [123] 

4xl0 5 (2xl05/7) Activity / cassette mutagenesis / selection [88] 

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