Original Article

Amino Acids

, Volume 43, Issue 6, pp 2301-2311

First online:

l-Valine production with minimization of by-products’ synthesis in Corynebacterium glutamicum and Brevibacterium flavum

  • Xiaohu HouAffiliated withLaboratory of Renewable Energy and Gas Hydrate, Chinese Academy of SciencesGuangzhou Institute of Energy Conversion, Chinese Academy of SciencesThe Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, JiangNan University Email author 
  • , Xinde ChenAffiliated withLaboratory of Renewable Energy and Gas Hydrate, Chinese Academy of SciencesGuangzhou Institute of Energy Conversion, Chinese Academy of Sciences
  • , Yue ZhangAffiliated withThe Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, JiangNan University
  • , He QianAffiliated withThe Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, JiangNan University
  • , Weiguo ZhangAffiliated withThe Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, JiangNan University

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

Corynebacterium glutamicum ATCC13032 and Brevibacterium flavum JV16 were engineered for l-valine production by over-expressing ilvEBN r C genes at 31 °C in 72 h fermentation. Different strategies were carried out to reduce the by-products’ accumulation in l-valine fermentation and also to increase the availability of precursor for l-valine biosynthesis. The native promoter of ilvA of C. glutamicum was replaced with a weak promoter MPilvA (P-ilvAM1CG) to reduce the biosynthetic rate of l-isoleucine. Effect of different relative dissolved oxygen on l-valine production and by-products’ formation was recorded, indicating that 15 % saturation may be the most appropriate relative dissolved oxygen for l-valine fermentation with almost no l-lactic acid and l-glutamate formed. To minimize l-alanine accumulation, alaT and/or avtA was inactivated in C. glutamicum and B. flavum, respectively. Compared to high concentration of l-alanine accumulated by alaT inactivated strains harboring ilvEBN r C genes, l-alanine concentration was reduced to 0.18 g/L by C. glutamicum ATCC13032MPilvAavtA pDXW-8-ilvEBN r C, and 0.22 g/L by B. flavum JV16avtA::Cm pDXW-8-ilvEBN r C. Meanwhile, l-valine production and conversion efficiency were enhanced to 31.15 g/L and 0.173 g/g by C. glutamicum ATCC13032MPilvAavtA pDXW-8-ilvEBN r C, 38.82 g/L and 0.252 g/g by B. flavum JV16avtA::Cm pDXW-8-ilvEBN r C. This study provides combined strategies to improve l-valine yield by minimization of by-products’ production.

Keywords

l-Valine Corynebacterium glutamicum Brevibacterium flavum alaT avtA