Cell surface display of a beta -glucosidase employing the type V secretion system on ethanologenic Escherichia coli for the fermentation of cellobiose to ethanol.

摘要

We used the autodisplay system AIDA-I, which belongs to the type V secretion system (TVSS), to display the beta -glucosidase BglC from Thermobifida fusca on the outer membrane of the ethanologenic Escherichia coli strain MS04 (MG1655 Delta pflB, Delta adhE, Delta frdA, Delta xylFGH, Delta ldhA, PpflB::pdc_Zm-adhB_Zm). MS04 that was transformed with the plasmid pAIDABglCRHis showed cellobiase activity (171 U/g_CDW) and fermented 40 g/l cellobiose in mineral medium in 60 h with an ethanol yield of 81% of the theoretical maximum. Whole-cell protease treatment, SDS-PAGE, and Western-blot analysis demonstrated that BglC was attached to the external surface of the outer membrane of MS04. When attached to the cells, BglC showed 93.3% relative activity in the presence of 40 g/l ethanol and retained 100% of its activity following 2 days of incubation at 37 degrees C with the same ethanol concentration. This study shows the potential of the TVSS (AIDA-I) and BglC as tools for the production of lignocellulosic bio-commodities.