L-lactic acid production by Aspergillus brasiliensis overexpressing the heterologous ldha gene from Rhizopus oryzae

Microbial Cell Factories

Research

Nicolas Fabre¹  Sylvaine Crapart¹  Anthony Levasseur²  Marie-Noëlle Rosso³  Isabelle Herpoël-Gimbert⁴  Sana Raouche⁴  Jean-Claude Sigoillot⁴  Nadège Liaud⁵ 

[1] ARD Agro-Industrie Recherche et Développement, Route de Bazancourt, 51110, Pomacle, France;Aix-Marseille Université, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), UM63, CNRS 7278, IRD 198, INSERM U1095, IHU Méditerranée Infection, Pôle des Maladies Infectieuses, Assistance Publique-Hôpitaux de Marseille, Faculté de Médecine, 27 Bd Jean Moulin, 13005, Marseille, France;INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Polytech’ Marseille, 163 avenue de Luminy, CP 925, 13288, Cedex 09, Marseille, France;INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Polytech’ Marseille, 163 avenue de Luminy, CP 925, 13288, Cedex 09, Marseille, France;Aix-Marseille Université, UMR1163 Biodiversité et Biotechnologie Fongiques, Polytech’ Marseille, 163 avenue de Luminy, CP 925, 13288, Cedex 09, Marseille, France;INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Polytech’ Marseille, 163 avenue de Luminy, CP 925, 13288, Cedex 09, Marseille, France;Aix-Marseille Université, UMR1163 Biodiversité et Biotechnologie Fongiques, Polytech’ Marseille, 163 avenue de Luminy, CP 925, 13288, Cedex 09, Marseille, France;ARD Agro-Industrie Recherche et Développement, Route de Bazancourt, 51110, Pomacle, France;

关键词: Lactic Acid;    Xylose;    Gluconic Acid;    Itaconic Acid;    Lactic Acid Production;   

DOI  :  10.1186/s12934-015-0249-x

 received in 2015-01-05, accepted in 2015-04-23,  发布年份 2015

来源: Springer

【 摘 要 】

BackgroundLactic acid is the building block of poly-lactic acid (PLA), a biopolymer that could be set to replace petroleum-based plastics. To make lactic acid production cost-effective, the production process should be carried out at low pH, in low-nutrient media, and with a low-cost carbon source. Yeasts have been engineered to produce high levels of lactic acid at low pH from glucose but not from carbohydrate polymers (e.g. cellulose, hemicellulose, starch). Aspergilli are versatile microbial cell factories able to naturally produce large amounts of organic acids at low pH and to metabolize cheap abundant carbon sources such as plant biomass. However, they have never been used for lactic acid production.ResultsTo investigate the feasibility of lactic acid production with Aspergillus, the NAD-dependent lactate dehydrogenase (LDH) responsible for lactic acid production by Rhizopus oryzae was produced in Aspergillus brasiliensis BRFM103. Among transformants, the best lactic acid producer, A. brasiliensis BRFM1877, integrated 6 ldhA gene copies, and intracellular LDH activity was 9.2 × 10−2 U/mg. At a final pH of 1.6, lactic acid titer reached 13.1 g/L (conversion yield: 26%, w/w) at 138 h in glucose-ammonium medium. This extreme pH drop was subsequently prevented by switching nitrogen source from ammonium sulfate to Na-nitrate, leading to a final pH of 3 and a lactic acid titer of 17.7 g/L (conversion yield: 47%, w/w) at 90 h of culture. Final titer was further improved to 32.2 g/L of lactic acid (conversion yield: 44%, w/w) by adding 20 g/L glucose to the culture medium at 96 h. This strain was ultimately able to produce lactic acid from xylose, arabinose, starch and xylan.ConclusionWe obtained the first Aspergillus strains able to produce large amounts of lactic acid by inserting recombinant ldhA genes from R. oryzae into a wild-type A. brasiliensis strain. pH regulation failed to significantly increase lactic acid production, but switching nitrogen source and changing culture feed enabled a 1.8-fold increase in conversion yields. The strain produced lactic acid from plant biomass. Our findings make A. brasiliensis a strong contender microorganism for low-pH acid production from various complex substrates, especially hemicellulose.

【 授权许可】

Unknown   
© Liaud et al.; licensee BioMed Central. 2015. 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.