Enhancing cobalamin (vitamin B12) production in E. coli to address demand and global security

点击翻译按钮获取中文摘要

Anemia is a public health condition of epidemic proportions, affecting 30% of the worlds' population (2 billion people). The highest prevalence is in preschool-age children and pregnant women. The condition results in ill-health (weakness, cognitive-development), premature death and reduction in work capacity of entire populations, bringing serious economic consequences to countries and continents. Although anaemia has been recognized as a public health problem for many years, little progress has been reported and the global prevalence of anaemia remains unacceptably high. WHO and UNICEF emphasize the urgent need to combat anaemia and stress the importance of recognizing its multifactorial etiology for developing effective control programmes. Iron deficiency accounts for around a third of anaemia cases, but significantly vitamin B12 deficiency has been identified as one of the major components of pernicious (or non-iron deficient) anaemia, which is further associated with spina bifida, higher levels of brain atrophy in the elderly and is linked with the development of cardiovascular disease and diabetes. A world-wide B12-supplementation programme would have a significant effect but this has so far not been attempted because the current price of vitamin B12, which is also referred to as cobalamin, is prohibitively expensive, especially for developing countries where it is needed most. Moreover, around 90% of B12 is made in China which raises nutrition security issues in the event of conflict or natural disasters. Not only is the nutrient important for human health it is also important as a supplement for animal feeds and for certain industrial processes such as the biological production of methionine and 1,3-propanediol.Vitamin B12 is one of the few vitamins and nutrients that is produced through fermentation. It is also one of the lowest yielding processes with the nutrient being produced only at around 400 mg/L of culture. This low yield is coupled with a strain that grows very slowly making the overall production very inefficient. In this project we will apply a combination of rational and random screens to develop a high-yielding producer of B12 in E. coli, building on the pathway knowledge of the Warren group and the world-leading expertise of DuPont/Tate & Lyle in strain development and optimisation. The project will result in the generation of a strain that will produce B12 on the g/L scale, ensuring a ready supply of the nutrient for commercial and humanitarian requirements.This project will provide basic and fundamental insights into the control and regulation of the B12 pathway. Our work will help identify some of the key bottlenecks in the biosynthesis, which is one of the most complex found in biological systems, and develop methods to overcome these issues. The project aims to reduce of the complexity in the pathway by using biosynthetic enzymes that lack inhibitory constraints. The pathway will be engineered into E. coli using gene editing technology to allow for optimal expression of the relevant genes. The strain will be further engineered to allow for the cellular procurement of the various building blocks that are required in the construction of the molecule. This project therefore looks to apply synthetic biology approaches to a current real-world problem and in so-doing will deliver a strain that will have enormous benefit to both industry and the nutrition markets.For this LINK project, DuPont/Tate & Lyle will provide a total of £470k, including a £100k cash investment, which will go towards funding a full-time technician.