1. Mixed carbon substrates: a necessary nuisance or a missed opportunity?
- Author
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Liu, Nian, Santala, Suvi, and Stephanopoulos, Gregory
- Subjects
- *
GENETIC techniques , *MICROBIAL metabolism , *GENETIC engineering , *CARBON , *NUISANCES - Abstract
• Efficient co-utilization of substrate mixtures is necessary for using many renewable feedstocks, adding a layer of complexity in fermentation. • In contrast, with judicious design of substrate pairs, intentional application of mixed carbon sources can optimize cellular metabolism. • The benefits of using mixed substrates are summarized into four distinct categories, with emphasis on how they enable better product formation. • Mixed substrate fermentation along with existing engineering methods can potentially emerge as a new strategy to further enhance cell performance. Although fermentation with single carbon sources is the preferred mode of operation in current industrial biotechnology, the use of multiple substrates has been continuously investigated throughout the years. Generally, microbial metabolism varies significantly when cells are presented with mixed carbon substrates compared to a single carbon-energy source, as different nutrients interact in complex ways within the metabolic network. By exploiting these distinct modes of interaction, researchers have identified unique opportunities to optimize metabolism using mixed carbon sources. Here we review situations where process yield and productivity are markedly improved through the judicious introduction of substrate mixtures. Our goal is to illustrate that with proper design of the choice of substrates and the way they are introduced to cultures, metabolic optimization with mixed substrates can be a unique strategy that complements genetic engineering techniques to enhance cell performance beyond what is accomplished in single substrate fermentations. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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