Scheme of the MLSDS method. The case of three-lines is shown. Uppermost three boxes indicate the state in the DNA synthesizers after the first three synthetic cycles, that is, partial mixtures of triplet codons attached to the CPGs. 1, 2 and 3 denote 1st, 2nd and 3rd letter mixture in the line-1 DNA synthesizer, respectively. Their A:T:G:C mixing ratios are designed with the GA program so that 123 gives a partial mixture of triplet codons without any stop codons. In the same way, 456 and 789 denote corresponding partial mixtures of triplet codons in the line-2 and the line-3 DNA synthesizers, respectively. The equimolar mixture of 123, 456 and 789, which is obtained after split-and-mix procedure, can be designed to give approximately the target amino acid composition without stop codons. Examples of 1,2,.....,9 are shown in Table 1.