Fig. 4
Biotransformation of styrene by the wild type and the site-saturation mutations at D305. The whole cell biotransformation was conducted by the recombinant cells of BL21/pET-28a-styABD305X-fdh and its wild type (X = V, A, G). The reaction was carried out in 50 mL flasks with 10 mL of KP buffer (200 mM, pH 8.0) containing 26 mM of substrate styrene and 1.0 g cell of dry weight with addition of 50% (v/v) hexadecane at 30 °C and 220 rpm on a rotatory shaker for 15 min. After incubation, the product was withdrawn and subjected to the reverse phase HPLC analysis. The reaction mixture was used to determine specific epoxidation activities. The enzyme activity of wild type was set to 100%, corresponding to the initial activity of 72 ± 10 U/g CDW. All assays were performed in triplicate and the standard deviations of the biological replicates are represented by error bars