FIGURE 1.

Esterase activity of PL_GOS. (A) Hydrolysis of pNP-butyrate by PL-GOS. Crude extract from Escherichia coli MG1655 cells expressing PL-GOS (strain TMMGP1503) and lipase A (strain TMMGPK) from Bacillus subtilis was used. Crude extract from E. coli TMMGP (empty vector) served as negative control. Activity of crude extracts was tested in tris-HCl-buffer, pH 7.3 and artificial seawater. PL-GOS activity increased in artificial seawater, while lipase A activity decreased. Plate based lipolytic assays with triolein/rhodamin (B) and tributyrate as substrate (C) show no lipase activity in E. coli TMMGP1503 expressing PL-GOS from a plasmid. E. coli TMMGPK expressing Lipase A from B. subtilis was used as a positive control and E. coli TMMGP with an empty vector was used as negative control.