Team:Paris Bettencourt/Project/VitaminA

Ferment It Yourself

iGEM Paris-Bettencourt 2O15

• Background
• Design
• Project
  Micronutrients
  Continuity
  Modeling
  Manufacturing
• Achievements
  Results
  Parts
  Medal Fulfillments
• Practices
  Overview
  SynBio Challenge
  DIλ
  Acceptance
  Events
  Rhizi
  Collaborations
• Safety
  Safety Overview
  Safety Form
  Review Board
• Notebook
  Daily notebook
  Protocols
  Bibliography
• Team
  Members
  Attributions
  Acknowledgments
  Press
  Official Team Profile

Vitamin A

Background	Aims	Results
The yeast S. cerevisiae can be engineered to produce ß-carotene, a precursor of vitamin A.	Evaluate the growth and vitamin production of S. cerevisiae in idli. Improve the ß-carotene yield of S. cerevisiae.	Showed that the vitamin A producing yeast grows as fast as the wild type. Showed that the engineered S. cerevisiae can significantly increase the amount of vitamin A in idli. Designed a way to further improve the vitamin A synthesis.

Motivation

Vitamin A deficiency is a crucial issue in India, affecting millions of people.
+ numbers and consequences of deficiency
The government developed different programs to provide people with vitamin A supplements, but they are not very convenient (people need to go to a center everyday to receive it), only help a small portion of the population, and the retinol present in the supplements is not as healthy as the ß-carotene found in food. Another solution which has been proposed is Golden Rice, a rice that have been genetically engineered to synthesize vitamin A. However, the Golden Rice is the subject of many controversies, and has not been implemented in India.
Our idea is to have the vitamin A produced by the microbiome of fermented foods, and not by the cereal itself. It is much more easier, cheaper and faster to genetically engineer micro-organisms than plants. And for the consumer, it is much less intrusive and constraining to have a starter of yeast and bacteria which they can chose to add or not in their food at anytime, than to have to change their entire crops as proposed by the Golden Rice project.

Design

To produce vitamin A in idli, a popular indian rice cake that is fermented, we chose to use the yeast Saccharomyces cerevisiae since it is commonly found in idli batter (Soni and Sandhu, 1989 and Nout, 2009). So it has a better chance to grow well and not affect the taste of idli than a yeast that isn’t normally present in the batter. Though S. cerevisiae doesn’t naturally produces ß-carotene, it has been shown that with the introduction of two carotenogenic genes from the carotenoid-producing ascomycete Xanthophyllomyces dendrorhous, S. cerevisiae could synthesize ß-carotene (Verwaal et al., 2007). These two genes are crtYB which codes for phytoene synthase and lycopene cyclase, and crtI, which encodes phytoene desaturase.

Additional overexpression of crtE (GGPP synthase) from X. dendrorhous, and an additional copy of a truncated 3-hydroxy-3-methylglutaryl-coenzyme A reductase gene (tHMG1) from S. cerevisiae were both reported to increase the carotenoid production levels in S. cerevisiae (Verwaal et al., 2007). A more recent study also showed that ß-carotene synthesis in this yeast could also be increased with codon-optimization of crtI and crtYB, and by introducing the HMG-CoA reductase (mva) from Staphyloccocus aureus rather than the truncated HMG-CoA reductase (tHMG1) from S. cerevisiae (Li, 2013).

HMG-CoA: 3-hydroxy-3-methylglutaryl-coenzyme A
HMG1 and HMG2 (paralogs): HMG-CoA reductase
IPP: isopentenyl pyrophosphate
DMAPP: dimethylallyl pyrophosphate
GPP: geranyl diphosphate
FPP: farnesyl pyrophosphate
GGPP: geranylgeranyl-diphosphate
CrtE: GGPP synthase
CrtYB: lycopene cyclase/phytoene synthase
CrtI: phytoene desaturase