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Table 2 Functional characterization of constructs used in the overexpression of glycerol utilization and L-lactate synthesis enzymes

From: Efficient synthesis of L-lactic acid from glycerol by metabolically engineered Escherichia coli

  Activity (μmol/mg protein/min)a
Enzyme tested LA20 (Control)b LA20 (Overexpressed)c
Glycerol kinase 0.187 ± 0.005 0.669 ± 0.004
Aerobic glycerol-3-phosphate dehydrogenase 0.017 ± 0.001 0.027 ± 0.002
Glycerol dehydrogenase 0.049 ± 0.002 0.39 ± 0.02
Dihydroxyacetone kinase 0.005 ± 0.001 0.019 ± 0.002
L-Lactate dehydrogenase 0.136 ± 0.005 0.68 ± 0.06
  1. a All activities were measured as described in Materials and Methods and values are reported as average ± standard deviation for triplicate assays.
  2. b Activities measured in strain LA20 containing the blank vector.
  3. c Activities measured in strain LA20 containing a plasmid overexpressing the specified enzyme: i.e. pZSKLMgldA for glycerol dehydrogenase and dihydroxyacetone kinase, pZSglpKglpD for glycerol kinase and aerobic glycerol-3-phosphate dehydrogenase, and pZSldh for S. bovis L-lactate dehydrogenase.
  4. Reported values are from 36-hour shake flask cultures.