Ag43-mediated display of a thermostable β-glucosidase in Escherichia coli and its use for simultaneous saccharification and fermentation at high temperatures

Microbial Cell Factories

Research

Cessna Moss-Acosta¹  Alfredo Martinez¹  Guillermo Gosset¹  Berenice Trujillo-Martinez¹  Iván Muñoz-Gutiérrez² 

[1] Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, A. P. 510-3, 62250, Cuernavaca, Mor, México;Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, A. P. 510-3, 62250, Cuernavaca, Mor, México;Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel;

关键词: Ethanologenic Escherichia coli;    Simultaneous saccharification and fermentation;    Cellulose;    Autotransporter Ag43;    Thermobifida fusca β-glucosidase;    Ethanol;   

DOI  :  10.1186/s12934-014-0106-3

 received in 2014-05-19, accepted in 2014-07-14,  发布年份 2014

来源: Springer

【 摘 要 】

BackgroundThe autotransporter (AT) system can potentially be used in the secretion of saccharolytic enzymes for the production of lignocellulosic biofuels and chemicals using Escherichia coli. Although ATs share similar structural characteristics, their capacity for secreting heterologous proteins widely varies. Additionally, the saccharolytic enzyme selected to be secreted should match the cell growth or cell fermentation conditions of E. coli.ResultsIn the search for an AT that suits the physiological performance of the homo-ethanologenic E. coli strain MS04, an expression plasmid based on the AT antigen 43 (Ag43) from E. coli was developed. The β-glucosidase BglC from the thermophile bacterium Thermobifida fusca was displayed on the outer membrane of the E. coli strain MS04 using the Ag43 system (MS04/pAg43BglC). This strain was used to hydrolyze and ferment 40 g/L of cellobiose in mineral media to produce 16.65 g/L of ethanol in 48 h at a yield of 81% of the theoretical maximum. Knowing that BglC shows its highest activity at 50°C and retains more than 70% of its activity at pH 6, therefore E. coli MS04/pAg43BglC was used to ferment crystalline cellulose (Avicel) in a simultaneous saccharification and fermentation (SSF) process using a commercial cocktail of cellulases (endo and exo) at pH 6 and at a relatively high temperature for E. coli (45°C). As much as 22 g/L of ethanol was produced in 48 h.ConclusionsThe Ag43-BglC system can be used in E. coli strains without commercial β-glucosidases, reducing the quantities of commercial enzymes needed for the SSF process. Furthermore, the present work shows that E. coli cells are able to ferment sugars at 45°C during the SSF process using 40 g/L of Avicel, reducing the gap between the working conditions of the commercial saccharolytic enzymes and ethanologenic E. coli.

【 授权许可】

Unknown   
© Muñoz-Gutiérrez et al.; licensee BioMed Central Ltd. 2014. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.