Levan degradation by <i>Escherichia coli</i> expressing endo-levanase BT1760 of <i>Bacteroides thetaiotaomicron</i> from the pURI3-BT1760Cter plasmid.

<p>(A) 5 μL of the liquid culture of recombinant <i>E</i>. <i>coli</i> was spotted onto a LB plate containing Amp, IPTG and 5 g/L of Lsc3-produced HMW levan and grown overnight at room temperature. Agar discs were cut off from regions marked with black rings, melted by heating and 0.5 μL of the sample was applied to a thin layer chromatography (TLC) plate. (B) TLC analysis of levan degradation from regions 3–6 of the agar plate in panel A and on lanes 7 and 8 products from 5 g/L levan by 1 h and 4 days of reaction with the lysate from recombinant <i>E</i>. <i>coli</i>. The chromatogram was developed in chloroform: methanol: water (90:65:15, v/v/v). Reference sugars on the TLC plate: fructose (F) and 1-kestose (K) on lane 1; sucrose (S) and nystose (N) on lane 2. F1-F5; levan degradation products with respective degree of polymerization.