Engineered probiotics are the next-generation biotherapeutics edited to target specific diseases. However, there are no reasonable solutions to several problems, such as colonization failure, insufficient population density, and irregular expression of exogenous genes in vivo.
With the increasing focus on the harm of a high-sugar diet, numerous people intend to consume sugar substitutes rather than sugar itself. From 2015-2019, erythritol consumption in China with a growth rate of 89.7% in 2018 and 100% in 2019. Erythritol has become common in Chinese life.
Unlike several traditional sugar substitutes such as aspartame, erythritol cannot be used by human body or intestinal microbiome(Suez et al.,2022), which has good anti-caries, anti-diabetes and other effects(Wölnerhanssen et al.,2020). The excellent security and complete zero heat made it show an obvious growth trend from 2015 to 2019, making it one of the most common flavoring agent in China.
Here, we designed an engineered probiotic platform based on erythritol. With the regular erythritol-adding diet, the colonization duration, population density of engineered probiotics will be enhanced and the curing genes will be induced safely in vivo. Meanwhile, We also gave our engineered bacteria more applications, making it a multi-function platform that benefits human health and cures specific diseases.
Since none of intestinal flora utilized the erythritol, we thought it meaningful to introduce a metabolic pathway into our engineered probiotics. Consuming the extra nutrition erythritol, the growth of engineered probiotics will be enhanced, making it competitive and, thus, solving the problem of the colonization of engineered bacteria.
We found a rare erythritol utilizing pathway from Brucella abortus (Thanks to Professor Jiabo Ding's research team at the Institute of Animal Sciences, Chinese Academy of Agricultural Sciences (CAAS), we’re free from Brucella, an extremely dangerous pathogen). Considering the high demand for safety, we chose E. coli as a commonly used prokaryotic substrate chassis organism for higher compatibility in building this probiotic platform. Thus, we introduced the erythritol metabolic pathway and constructed a strain that could exclusively use erythritol as a carbon source(Barbier et al.,2014). This characteristic makes it competitive in the intestinal flora and, thus, shows a better effect in biotherapy.
Fig 1. Metabolic pathway from erythritol to D-erythrose-4-P in Brucella abortus
Scientists found that the erythritol-based gene regulation system(ery operon) showed a similar structure with lac operon(Qiu et al.,2020).The transcriptional regular protein EryD, binds the ery promoter (pEry) and locked the expression of the ery operon without the erythritol. The erythritol works as a inducer in this system, showing great potential of a in vivo induction platform. Here, we tested the function of eryD, pEry and eryO in E. coli, and further demostrated the feasibility of erythritol induction system in E. coli.
Fig 2. The structure and visualization of ery operon in Brucella abortus
Besides getting a large population density and well localization, we also introduced several
pathways to give our platform more applications, making it more relevant to the therapeutic
topic. Our engineered probiotcs could synthesize a coenzyme, pyrroloquinoline quinone (PQQ),
for
benefiting our liver and nerves, and a rare sugar, L-erythrose, for lowering blood sugar and
blood pressure. Meanwhile, in order to further demonstrate the function of our platform, we
tested the expression of two curing genes from our partnership team HZAU-China, for reducing
the
risks of thrombosis under our engineered strain.
Learn More
Metabolism plays a crucial role in human health and disease, and weight management is a hot
topic concerning it.
Here, we propose a web-based simulator to predict the recommended calorie intake during
weight
loss and also to give personalized diet plans, which allows users to make personalized
calorie
and physical activity plans to reach a goal weight within a specific period, maintain it
afterward, and at the same time recommends personalized diet plans that for Chinese based on
the
calculated daily calorie intake above.
Go planning your body!
Barbier T, Collard F, Zúñiga-Ripa A, et al. Erythritol feeds the pentose phosphate pathway via three new isomerases leading to D-erythrose-4-phosphate in Brucella. Proc Natl Acad Sci U S A. 2014;111(50):17815-17820. doi:10.1073/pnas.1414622111
Qiu X, Xu P, Zhao X, Du G, Zhang J, Li J. Combining genetically-encoded biosensors with high throughput strain screening to maximize erythritol production in Yarrowia lipolytica. Metab Eng. 2020;60:66-76. doi:10.1016/j.ymben.2020.03.006
Suez J, Cohen Y, Valdés-Mas R, et al. Personalized microbiome-driven effects of non-nutritive sweeteners on human glucose tolerance. Cell. 2022;185(18):3307-3328.e19. doi:10.1016/j.cell.2022.07.016
Wölnerhanssen BK, Meyer-Gerspach AC, Beglinger C, Islam MS. Metabolic effects of the natural sweeteners xylitol and erythritol: A comprehensive review. Crit Rev Food Sci Nutr. 2020;60(12):1986-1998. doi:10.1080/10408398.2019.1623757