Journal of Microbial & Biochemical Technology

Monascus ruber as cell factory for lactic acid production at low pH

CO-ORGANIZED EVENT: International Conference on Chronic Diseases & 6^th International Conference on Microbial Physiology and Genomics

August 31-September 01, 2017 Brussels, Belgium

Ruud A Weusthuis, Astrid E Mars, Jan Springer, Emil J H Wolbert, Hetty van der Wal, Truus G de Vrije, Mark Levisson, Audrey Leprince, G Bwee Houweling-Tan, Antoine P H A Moers, Sjon N A Hendriks, Odette Mendes, Yvonne Griekspoor, Marc W T Werten, Peter J Schaap, John van der Oost and Gerrit Eggink

Wageningen University & Research, The Netherlands

Scientific Tracks Abstracts: J Microb Biochem Technol

Abstract:

A Monascus ruber strain was isolated that was able to grow on mineral medium at high sugar concentrations and 175 g/l lactic acid at pH 2.8. Its genome and transcriptomes were sequenced and annotated. Genes encoding lactate dehydrogenase (LDH) were introduced to accomplish lactic acid production and two genes encoding pyruvate decarboxylase (PDC) were knocked out to subdue ethanol formation. The strain preferred lactic acid to glucose as carbon source, which hampered glucose consumption and therefore also lactic acid production. Lactic acid consumption was stopped by knocking out 4 cytochromedependent LDH (CLDH) genes, and evolutionary engineering was used to increase the glucose consumption rate (figure 1). Application of this strain in a fed-batch fermentation resulted in a maximum lactic acid titer of 190 g/l at pH 3.8 and 129 g/l at pH 2.8, respectively 1.7 and 2.2 times higher than reported in literature before. Yield and productivity were on par with the best strains described in literature so far.

Biography :

Ruud A Weusthuis obtained his PhD in Microbial Biotechnology at the Delft University of Technology (1989-1994) after studying Biology in Groningen (1984-1989). Then he joined the WUR and headed the Bioconversion Group (2004-2008). In 2007, he started working at the Wageningen University, and is active as Associate Professor of Microbial Biotechnology. He focuses on the efficient production of chemicals by microorganisms.