Large-scale production of tauroursodeoxycholic acid products through fermentation optimization of engineered Escherichia coli cell factory

Metabolic engineering and optimization of Escherichia coli co-culture for the de novo synthesis of genkwanin

Genkwanin has various significant roles in nutrition, biomedicine, and pharmaceutical biology. Previously, this compound was chiefly produced by plant-originated extraction or chemical synthesis. However, due to increasing concern and demand for safe food and environmental issues, the biotechnological production of genkwanin and other bioactive compounds based on safe, cheap, and renewable substrates has gained much interest. This paper described recombinant Escherichia coli-based co-culture engineering that was reconstructed for the de novo production of genkwanin from d-glucose. The artificial genkwanin biosynthetic chain was divided into 2 modules in which the upstream strain contained the genes for synthesizing p-coumaric acid from d-glucose, and the downstream module contained a gene cluster that produced the precursor apigenin and the final product, genkwanin. The Box-Behnken design, a response surface methodology, was used to empirically model the production of genkwanin and optimize its productivity. As a result, the application of the designed co-culture improved the genkwanin production by 48.8 ± 1.3 mg/L or 1.7-fold compared to the monoculture. In addition, the scale-up of genkwanin bioproduction by a bioreactor resulted in 68.5 ± 1.9 mg/L at a 48 hr time point. The combination of metabolic engineering and fermentation technology was therefore a very efficient and applicable approach to enhance the production of other bioactive compounds.

Biological synthesis of ursodeoxycholic acid

Ursodeoxycholic acid (UDCA) is a fundamental treatment drug for numerous hepatobiliary diseases that also has adjuvant therapeutic effects on certain cancers and neurological diseases. Chemical UDCA synthesis is environmentally unfriendly with low yields. Biological UDCA synthesis by free-enzyme catalysis or whole-cell synthesis using inexpensive and readily available chenodeoxycholic acid (CDCA), cholic acid (CA), or lithocholic acid (LCA) as substrates is being developed. The free enzyme-catalyzed one-pot, one-step/two-step method uses hydroxysteroid dehydrogenase (HSDH); whole-cell synthesis, mainly uses engineered bacteria (mainly Escherichia coli) expressing the relevant HSDHs. To further develop these methods, HSDHs with specific coenzyme dependence, high enzyme activity, good stability, and high substrate loading concentration, P450 monooxygenase with C-7 hydroxylation activity and engineered strain harboring HSDHs must be exploited.

Tailoring and optimizing fatty acid production by oleaginous yeasts through the systematic exploration of their physiological fitness

Background

The use of palm oil for our current needs is unsustainable. Replacing palm oil with oils produced by microbes through the conversion of sustainable feedstocks is a promising alternative. However, there are major technical challenges that must be overcome to enable this transition. Foremost among these challenges is the stark increase in lipid accumulation and production of higher content of specific fatty acids. Therefore, there is a need for more in-depth knowledge and systematic exploration of the oil productivity of the oleaginous yeasts. In this study, we cultivated Cutaneotrichosporon oleaginosus and Yarrowia lipolytica at various C/N ratios and temperatures in a defined medium with glycerol as carbon source and urea as nitrogen source. We ascertained the synergistic effect between various C/N ratios of a defined medium at different temperatures with Response Surface Methodology (RSM) and explored the variation in fatty acid composition through Principal Component Analysis.

Results

By applying RSM, we determined a temperature of 30 °C and a C/N ratio of 175 g/g to enable maximal oil production by C. oleaginosus and a temperature of 21 °C and a C/N ratio of 140 g/g for Y. lipolytica. We increased production by 71% and 66% respectively for each yeast compared to the average lipid accumulation in all tested conditions. Modulating temperature enabled us to steer the fatty acid compositions. Accordingly, switching from higher temperature to lower cultivation temperature shifted the production of oils from more saturated to unsaturated by 14% in C. oleaginosus and 31% in Y. lipolytica. Higher cultivation temperatures resulted in production of even longer saturated fatty acids, 3% in C. oleaginosus and 1.5% in Y. lipolytica.

Conclusions

In this study, we provided the optimum C/N ratio and temperature for C. oleaginosus and Y. lipolytica by RSM. Additionally, we demonstrated that lipid accumulation of both oleaginous yeasts was significantly affected by the C/N ratio and temperature. Furthermore, we systematically analyzed the variation in fatty acids composition and proved that changing the C/N ratio and temperature steer the composition. We have further established these oleaginous yeasts as platforms for production of tailored fatty acids.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12934-022-01956-5.

Natural bear bile powder suppresses neuroinflammation in lipopolysaccharide-treated mice via regulating TGR5/AKT/NF-κB signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

According to the Tang Dynasty classics Dietetic Material Medica and the Ming Dynasty classics Compendium of Materia Medica records, bear bile powder (BBP) has been used to treat a variety of diseases, such as febrile seizures, the pathogenesis of which is associated to neuroinflammation. However, the mechanism of BBP on alleviating neuroinflammation remains unclear.

AIMS OF THE STUDY

Microglia can be activated by peripheral lipopolysaccharide (LPS) and play an important role in the pathogenesis of neuroinflammation. The purpose of this study is to investigate the effects and mechanism of BBP in inhibiting LPS-induced microglia inflammation in vitro and in vivo.

MATERIALS AND METHODS

The anti-microglia inflammatory effects and mechanism of BBP were assessed in LPS-treated BV2 microglial cells and in LPS-treated mice. The mRNA expression levels of the inflammatory factor and the protein expressions of cyclooxygenase-2 (COX2), inducible nitric oxide synthase (iNOS), takeda G-protein coupled receptor 5 (TGR5), nuclear factor-κB (NF-κB), inhibitor of NF-κB (IκBɑ), protein kinase B (AKT) in BV2 cells, mouse hippocampus and cortex were detected. The NF-κB transcription activity and NF-κB nuclear translocation were observed.

RESULTS

Our findings showed that BBP reduces branched process retraction and NO in LPS-treated BV2 cells, inhibits the protein expression of ionized calcium binding adaptor molecule 1 in the hippocampus of LPS-treated mice. Moreover, we observed that BBP decreases tumor necrosis factor α, interleukin (IL)-6 and IL-1β mRNA levels, deceases iNOS and COX-2 protein levels, increases TGR5 protein levels, suppresses the phosphorylation of AKT, NF-κB and IκBɑ protein in microglia both in vitro and in vivo. Further, we found that triamterene, the inhibitor of TGR5, abolishes the effects of BBP in LPS- treated BV2 cells.

CONCLUSION

BBP inhibits LPS-induced microglia activation, and the mechanism of its action is partly through TGR5/AKT/NF-κB signaling pathway.

A green strategy to produce potential substitute resource for bear bile using engineered Saccharomyces cerevisiae

BACKGROUND

Bear bile powder is a precious natural material characterized by high content of tauroursodeoxycholic acid (TUDCA) at a ratio of 1.00-1.50 to taurochenodeoxycholic acid (TCDCA).

RESULTS

In this study, we use the crude enzymes from engineered Saccharomyces cerevisiae to directionally convert TCDCA from chicken bile powder to TUDCA at the committed ratio in vitro. This S. cerevisiae strain was modified with heterologous 7α-hydroxysteroid dehydrogenase (7α-HSDH) and 7β-hydroxysteroid dehydrogenase (7β-HSDH) genes. S. cerevisiae host and HSDH gene combinatorial optimization and response surface methodology was applied to get the best engineered strain and the optimal biotransformation condition, respectively, under which 10.99 ± 0.16 g/L of powder products containing 36.73 ± 6.68% of TUDCA and 28.22 ± 6.05% of TCDCA were obtained using 12.00 g/L of chicken bile powder as substrate.

CONCLUSION

This study provides a healthy and environmentally friendly way to produce potential alternative resource for bear bile powder from cheap and readily available chicken bile powder, and also gives a reference for the green manufacturing of other rare and endangered animal-derived valuable resource.

Tauroursodeoxycholate-Bile Acid with Chaperoning Activity: Molecular and Cellular Effects and Therapeutic Perspectives

Tauroursodeoxycholic acid (TUDCA) is a naturally occurring hydrophilic bile acid that has been used for centuries in Chinese medicine. Chemically, TUDCA is a taurine conjugate of ursodeoxycholic acid (UDCA), which in contemporary pharmacology is approved by Food and Drug Administration (FDA) for treatment of primary biliary cholangitis. Interestingly, numerous recent studies demonstrate that mechanisms of TUDCA functioning extend beyond hepatobiliary disorders. Thus, TUDCA has been demonstrated to display potential therapeutic benefits in various models of many diseases such as diabetes, obesity, and neurodegenerative diseases, mostly due to its cytoprotective effect. The mechanisms underlying this cytoprotective activity have been mainly attributed to alleviation of endoplasmic reticulum (ER) stress and stabilization of the unfolded protein response (UPR), which contributed to naming TUDCA as a chemical chaperone. Apart from that, TUDCA has also been found to reduce oxidative stress, suppress apoptosis, and decrease inflammation in many in-vitro and in-vivo models of various diseases. The latest research suggests that TUDCA can also play a role as an epigenetic modulator and act as therapeutic agent in certain types of cancer. Nevertheless, despite the massive amount of evidence demonstrating positive effects of TUDCA in pre-clinical studies, there are certain limitations restraining its wide use in patients. Here, molecular and cellular modes of action of TUDCA are described and therapeutic opportunities and limitations of this bile acid are discussed.