Constitutive homologous expression of phosphoglucomutase and transaldolase increases the metabolic flux of Fusarium oxysporum

Microbial Cell Factories

Research

Diomi Mamma¹  Elisavet Kourtoglou¹  Silas G Villas-Boâs²  Dimitris G Hatzinikolaou³  George E Anasontzis⁴  Paul Christakopoulos⁵ 

[1] BIOtechMASS Unit, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Zografou, Athens, Greece;Centre for Microbial Innovation, School of Biological Sciences, The University of Auckland, Auckland, New Zealand;Department of Biology, Microbial Biotechnology Unit, Sector of Botany, National and Kapodistrian University of Athens, Zografou, Athens, Greece;Department of Biology, Microbial Biotechnology Unit, Sector of Botany, National and Kapodistrian University of Athens, Zografou, Athens, Greece;Department of Chemical and Biological Engineering, Industrial Biotechnology, Chalmers University of Technology, Gothenburg, Sweden;Division of Sustainable Process Engineering, Department of Civil, Environmental and Natural Resources Engineering, Biochemical and Chemical Process Engineering, Luleå University of Technology, SE-97187, Luleå, Sweden;

关键词: Phosphoglucomutase;    Transaldolase;    Metabolic flux;    Fungi;    PPP;    Glycolysis;    Metabolic engineering;   

DOI  :  10.1186/1475-2859-13-43

 received in 2014-01-07, accepted in 2014-03-14,  发布年份 2014

来源: Springer

【 摘 要 】

BackgroundFusarium oxysporum is among the few filamentous fungi that have been reported of being able to directly ferment biomass to ethanol in a consolidated bioprocess. Understanding its metabolic pathways and their limitations can provide some insights on the genetic modifications required to enhance its growth and subsequent fermentation capability. In this study, we investigated the hypothesis reported previously that phosphoglucomutase and transaldolase are metabolic bottlenecks in the glycolysis and pentose phosphate pathway of the F. oxysporum metabolism.ResultsBoth enzymes were homologously overexpressed in F. oxysporum F3 using the gpd A promoter of Aspergillus nidulans for constitutive expression. Transformants were screened for their phosphoglucomutase and transaldolase genes expression levels with northern blot. The selected transformant exhibited high mRNA levels for both genes, as well as higher specific activities of the corresponding enzymes, compared to the wild type. It also displayed more than 20 and 15% higher specific growth rate upon aerobic growth on glucose and xylose, respectively, as carbon sources and 30% higher biomass to xylose yield. The determination of the relative intracellular amino and non-amino organic acid concentrations at the end of growth on glucose revealed higher abundance of most determined metabolites between 1.5- and 3-times in the recombinant strain compared to the wild type. Lower abundance of the determined metabolites of the Krebs cycle and an 68-fold more glutamate were observed at the end of the cultivation, when xylose was used as carbon source.ConclusionsHomologous overexpression of phosphoglucomutase and transaldolase in F. oxysporum was shown to enhance the growth characteristics of the strain in both xylose and glucose in aerobic conditions. The intracellular metabolites profile indicated how the changes in the metabolome could have resulted in the observed growth characteristics.

【 授权许可】

Unknown   
© Anasontzis 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/2.0), 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.