Flavonoids are an important class of plant polyphenols that possess a variety of health benefits. In this work, S. cerevisiae was metabolically engineered to produce the flavonoid naringenin, using tyrosine as the precursor. Our strategy to improve naringenin production comprised three modules. In module 1, we employed a modified GAL system to overexpress the genes of the naringenin biosynthesis pathway and investigated their synergistic action. In module 2, we simultaneously up-regulated acetyl-CoA production and down-regulated fatty acid biosynthesis in order to increase the precursor supply, malonyl-CoA. In module 3, we engineered the tyrosine biosynthetic pathway to eliminate the feedback inhibition of tyrosine and also down-regulated competing pathways. It was found that modules 1 and 3 played important roles in improving naringenin production. We succeeded in producing up to ∼90 mg/L of naringenin in our final strain, which is a 20-fold increase as compared to the parental strain.
Kaempferol
is a polyphenolic compound with various reported health
benefits and thus harbors considerable potential for food-engineering
applications. In this study, a high-yield kaempferol-producing cell
factory was constructed by multiple strategies, including gene screening,
elimination of the phenylethanol biosynthetic branch, optimizing the
core flavonoid synthetic pathway, supplementation of precursor PEP/E4P,
and mitochondrial engineering of F3H and FLS. A total of 86 mg/L of
kaempferol was achieved in strain YL-4, to date the highest production
titer in yeast. Furthermore, a coculture system and supplementation
of surfactants were investigated, to relieve the metabolic burden
as well as the low solubility/possible transport limitations of flavonoids,
respectively. In the coculture system, the whole pathway was divided
across two strains, resulting in 50% increased cell growth. Meanwhile,
supplementation of Tween 80 in our engineered strains yielded 220
mg/L of naringenin and 200 mg/L of mixed flavonoidsamong the
highest production titer reported via de novo production in yeast.
The pathogenesis of inflammatory bowel disease (IBD) might be related to the local inflammatory damage and the dysbacteriosis of intestinal flora. Probiotics can regulate the intestinal flora and ameliorate IBD. The probiotic Bacillus subtilis strain B. subtilis JNFE0126 was used as the starter of fermented milk. However, the therapeutic effects of B. subtilis-fermented milk on IBD remain to be explored. In this research, the therapeutic effect of B. subtilis-fermented milk on dextran sulfate sodium salt (DSS)-induced IBD mouse model was evaluated. Besides, the expression of pro-inflammatory/anti-inflammatory cytokines, the proliferation of the intestinal stem cells, and the reconstruction of the mucosa barrier were investigated. Finally, alteration of the gut microbiota was investigated by taxonomic analysis. As shown by the results, the disease activity index (DAI) of IBD was significantly decreased through oral administration of B. subtilis (JNFE0126)-fermented milk, and intestinal mucosa injury was attenuated. Moreover, B. subtilis could reduce the inflammatory response of the intestinal mucosa, induce proliferation of the intestinal stem cell, and promote reconstruction of the mucosal barrier. Furthermore, B. subtilis could rebalance the intestinal flora, increasing the abundance of Bacillus, Alistipes, and Lactobacillus while decreasing the abundance of Escherichia and Bacteroides. In conclusion, oral administration of the B. subtilis-fermented milk could alleviate DSS-induced IBD via inhibition of inflammatory response, promotion of the mucosal barrier reconstruction, and regulation of the intestinal flora.
Terpenoids
and polyphenols are high-valued plant secondary metabolites.
Their high antimicrobial activities demonstrate their huge potential
as natural preservatives in the food industry. With the rapid development
of metabolic engineering, it has become possible to realize large-scale
production of non-native terpenoids and polyphenols by using the generally
recognized as safe (GRAS) strain, Saccharomyces cerevisiae, as a cell factory. This review will summarize the major terpenoid
and polyphenol compounds with high antimicrobial properties, describe
their native metabolic pathways as well as antimicrobial mechanisms,
and highlight current progress on their heterologous biosynthesis
in S. cerevisiae. Current challenges
and perspectives for the sustainable production of terpenoid and polyphenol
as natural food preservatives via S. cerevisiae will also be discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.