Boosting Prebiotic Production by Deleting a Key Gene in Bacteria

Greg Howard
13th July, 2024

Boosting Prebiotic Production by Deleting a Key Gene in Bacteria

Image Source: Natural Science News, 2024

Key Findings

  • Researchers from Universidade Do Minho developed a new method to produce fructooligosaccharides (FOS) using genetically modified Zymomonas mobilis
  • By deleting the sacC gene, which encodes invertase, they reduced unwanted by-products and increased FOS production
  • Using agro-industrial by-products like sugarcane molasses and corn steep liquor as nutrient sources, they achieved cost-effective and sustainable FOS production
Fructooligosaccharides (FOS) are gaining attention in the functional food market due to their prebiotic properties, which support beneficial gut bacteria. Traditionally, FOS are produced from sucrose using enzymes like fructosyltransferase or β-fructofuranosidase. However, these methods often result in low conversion rates and impure mixtures due to the release of high glucose levels. Researchers from Universidade Do Minho have developed a novel approach to address these challenges[1]. The team focused on Zymomonas mobilis, a bacterium known for its ethanol production, which naturally contains levansucrase enzymes capable of converting sucrose into FOS. By employing synthetic biology, they aimed to enhance FOS production by eliminating invertase (sacC) activity in Z. mobilis. Invertase typically competes with levansucrase for sucrose, leading to unwanted by-products. The researchers used homologous recombination with an engineered suicide plasmid to delete the sacC gene from the Z. mobilis ZM4 genome. This genetic modification resulted in a 70% reduction in monosaccharide production and a 9.0-fold increase in levan formation compared to the wild-type strain. The study also explored the use of agro-industrial by-products like sugarcane molasses and corn steep liquor (CSL) as nutrient sources for FOS production. This approach not only reduces costs but also promotes sustainability by utilizing waste materials. Implementing a fed-batch process with a medium composed of CSL and molasses (CSLM) at flask scale, the team achieved an FOS production of 41.9 g L−1 with a yield of 0.25 gFOS gsucrose−1. This innovative study builds on previous research. For instance, earlier studies have shown that Z. mobilis can be engineered to produce FOS in a one-step fermentation process[2]. The new study enhances this by eliminating invertase activity, thereby reducing substrate competition and increasing FOS yield. Additionally, the use of agro-industrial by-products as nutrient sources aligns with previous findings that molasses and aguamiel can be effective, low-cost alternatives for FOS production[3]. Further, the study's findings on enzyme activity and product specificity at different pH levels are consistent with earlier research on fructansucrases. These enzymes, part of the glycoside hydrolase family, can switch between producing short fructosaccharides and long-chain fructans like levan, depending on their structural form influenced by pH[4]. The new study leverages this knowledge by focusing on optimizing conditions for maximum FOS production. In conclusion, this research from Universidade Do Minho offers significant advancements in FOS production using genetically modified Z. mobilis. By eliminating invertase activity and utilizing agro-industrial by-products, the study not only improves efficiency but also promotes sustainability. This work paves the way for more cost-effective and environmentally friendly biotechnological strategies for prebiotic production.

BiotechGeneticsBiochem

References

Main Study

1) Improving Fructooligosaccharide Production via sacC Gene Deletion in Zymomonas mobilis: A Novel Approach for Enhanced Prebiotic Production

Published 12th July, 2024

https://doi.org/10.1007/s11947-024-03508-8

Related Studies

2) Tailoring fructooligosaccharides composition with engineered Zymomonas mobilis ZM4.

https://doi.org/10.1007/s00253-022-12037-3

3) Successive Fermentation of Aguamiel and Molasses by Aspergillus oryzae and Saccharomyces cerevisiae to Obtain High Purity Fructooligosaccharides.

https://doi.org/10.3390/foods11121786

4) Two active forms of Zymomonas mobilis levansucrase. An ordered microfibril structure of the enzyme promotes levan polymerization.

https://doi.org/10.1074/jbc.M805985200


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