Efficient production of 2'-fucosyllactose in unconventional yeast Yarrowia lipolytica

Metabolic engineering of Priestia megaterium for 2'-fucosyllactose production

BACKGROUND

2'-Fucosyllactose (2'-FL) is a predominant human milk oligosaccharide that significantly enhances infant nutrition and immune health. This study addresses the need for a safe and economical production of 2'-FL by employing Generally Recognized As Safe (GRAS) microbial strain, Priestia megaterium ATCC 14581. This strain was chosen for its robust growth and established safety profile and attributing suitable for industrial-scale production.

RESULTS

The engineering targets included the deletion of the lacZ gene to prevent lactose metabolism interference, introduction of α-1,2-fucosyltransferase derived from the non-pathogenic strain, and optimization of the GDP-L-fucose biosynthesis pathway through the overexpression of manA and manC. These changes, coupled with improvements in lactose uptake and utilization through random mutagenesis, led to a high 2'-FL yield of 28.6 g/L in fed-batch fermentation, highlighting the potential of our metabolic engineering strategies on P. megaterium.

CONCLUSIONS

The GRAS strain P. megaterium ATCC 14581 was successfully engineered to overproduce 2'-FL, a valuable human milk oligosaccharide, through a series of genetic modifications and metabolic pathway optimizations. This work underscores the feasibility of using GRAS strains for the production of oligosaccharides, paving the way for safer and more efficient methods in biotechnological applications. Future studies could explore additional genetic modifications and optimization of fermentation conditions of the strain to further enhance 2'-FL yield and scalability.

Maternal bisphenol A (BPA) exposure induces placental dysfunction and health risk in adult female offspring: Insights from a mouse model

Bisphenol A (BPA) is an endocrine disruptor that poses multiple risks to human health. In particular, the potential adverse effects of maternal exposure to BPA on offspring warrant further investigation. In this study, pregnant mice were exposed to BPA throughout gestation and the effects of BPA on placental function, fetal development, and health risks in adult offspring were assessed. The results showed that exposure to BPA during pregnancy led to abnormal fetal weight during the mid-to-late stages. Positron emission tomography (PET)/computed tomography (CT) and quantitative polymerase chain reaction (qPCR) were used to assess the expression of glucose transporters. The results showed that maternal BPA exposure altered glucose transport by upregulating Glut1. This alteration may significantly affect placental function and fetal development. Placental metabolomic analysis showed that BPA exposure led to downregulation of key intermediates in glucose metabolism, including UDP-d-glucose and D-glucosamine-6-phosphate. Additionally, the glycerophospholipid metabolite Dipalmitoylphosphatidylcholine (DPPC) was upregulated while CDP-choline and CDP-ethanolamine were downregulated. These disturbances in placental energy metabolism and alterations in glucose transport may be related to decreased fasting blood glucose levels and abnormal glucose tolerance in female offspring; however, these indices remained unaltered in male offspring. These findings provide preliminary insights into the potential pathological mechanisms underlying placental dysfunction and health risk caused by maternal BPA exposure in adult female offspring.

Construction of an engineered Escherichia coli for effective synthesis of 2'-fucosyllactose via the salvage pathway

2'-Fucosyllactose (2'-FL) is one of the important functional oligosaccharides in breast milk. So far, few attempts on biosynthesis of 2'-FL by the salvage pathway have been reported. Herein, the salvage pathway enzyme genes were introduced into the E. coli BL21star(DE3) for synthesis of 2'-FL. The 2'-FL titer increased from 1.56 to 2.13 g/L by deleting several endogenous genes on competitive pathways. The α-1,2-fucosyltransferase (WbgL) was selected, and improved the 2'-FL titer to 2.88 g/L. Additionally, the expression level of pathway enzyme genes was tuned through optimizing the plasmid copy number. Furthermore, the spatial distribution of WbgL was enhanced by fusing with the MinD C-tag. After optimizing the fermentation conditions, the 2'-FL titer reached to 7.13 g/L. The final strain produced 59.22 g/L of 2'-FL with 95% molar conversion rate of lactose and 92% molar conversion rate of fucose in a 5 L fermenter. These findings will contribute to construct a highly efficient microbial cell factory to produce 2'-FL or other HMOs.