Fig. 1From: Contribution of single amino acid and codon substitutions to the production and secretion of a lipase by Bacillus subtilis Schematic strategy to construct the lipA site saturation mutagenesis library. The expression vector pBSlipA, where the native lipA gene is under control of the constitutive P HpaII promoter, was used for construction of the lipA library by site saturation mutagenesis (SSM). The gene encodes the secretion signal (ssLipA) and the mature lipase (LipA). Each codon encoding an amino acid of the mature LipA with a conservation < 95% within the Firmicutes was considered for SSM using QuikChange® PCR with a degenerated “NNS” codon to randomly introduce every possible amino acid. Amino acids with a conservation ≥ 95% (|) were not considered for substitution and screening. In total, 155 out of 181 residues were substituted and the resulting variants subjected to screeningBack to article page