Biotechnological production of sphingoid bases and their applications

Metabolic profiling of two white-rot fungi during 4-hydroxybenzoate conversion reveals biotechnologically relevant biosynthetic pathways

White-rot fungi are efficient organisms for the mineralization of lignin and polysaccharides into CO2 and H2O. Despite their biotechnological potential, WRF metabolism remains underexplored. Building on recent findings regarding the utilization of lignin-related aromatic compounds as carbon sources by WRF, we aimed to gain further insights into these catabolic processes. For this purpose, Trametes versicolor and Gelatoporia subvermispora were incubated in varying conditions - in static and agitation modes and different antioxidant levels - during the conversion of 4-hydroxybenzoic acid (a lignin-related compound) and cellobiose. Their metabolic responses were assessed via transcriptomics, proteomics, lipidomics, metabolomics, and microscopy analyses. These analyses reveal the significant impact of cultivation conditions on sugar and aromatic catabolic pathways, as well as lipid composition of the fungal mycelia. Additionally, this study identifies biosynthetic pathways for the production of extracellular fatty acids and phenylpropanoids - both products with relevance in biotechnological applications - and provides insights into carbon fate in nature.

Regio-, Site- and Stereo-Selective Aziridination of Conjugated Dienes Enabled by Palladium/Copper/Iodide/Oxygen Cooperation

Vinylaziridines are important building blocks in organic chemistry, especially in the synthesis of nitrogen-containing heterocycles. The direct and efficient transfer of an appropriate nitrogen source to readily accessible conjugated dienes is a notable methodology. The Pd-catalyzed oxidative 1,2-difunctionalization of conjugated dienes through a π-allyl-palladium species should be an ideal method for the selective synthesis of vinylaziridines. However, this method faces the challenge of regioselectivity, often resulting in 1,4-difunctionalization instead. In this study, we developed a Pd-catalyzed aerobic 1,2-difunctionalization of conjugated dienes via a π-allyl-palladium species to achieve regio-, site- and stereo-selective aziridination under the synergistic effects of PdII, CuI, I-, and O2. The π-allyl palladium species formed in the system undergoes an unusual iodination process, leading to the formation of an allyl iodide intermediate. Subsequently, the vinylaziridine is obtained through intramolecular SN2' substitution of the allyl iodide.

Elucidation and engineering of Sphingolipid biosynthesis pathway in Yarrowia lipolytica for enhanced production of human-type sphingoid bases and glucosylceramides

Sphingolipids are vital membrane components in in mammalian cells, plants, and various microbes. We aimed to explore and exploit the sphingolipid biosynthesis pathways in an oleaginous and dimorphic yeast Yarrowia lipolytica by constructing and characterizing mutant strains with specific gene deletions and integrating exogenous genes to enhance the production of long-chain bases (LCBs) and glucosylceramides (GlcCers). To block the fungal/plant-specific phytosphingosine (PHS) pathway, we deleted the SUR2 gene encoding a sphinganine C4-hydroxylase, resulting in a remarkably elevated secretory production of dihydrosphingosine (DHS) and sphingosine (So) without acetylation. The Y. lipolytica SUR2 deletion (Ylsur2Δ) strain displayed retarded growth, increased pseudohyphal formation and stress sensitivity, along with the altered profiles of inositolphosphate-containing ceramides, GlcCers, and sterols. The subsequent disruption of the SLD1 gene, encoding a fungal/plant-specific Δ8 sphingolipid desaturase, restored filamentous growth in the Ylsur2Δ strain to a yeast-type form and further increased the production of human-type GlcCers. Additional introduction of mouse alkaline ceramidase 1 (maCER1) into the Ylsur2Δsld1Δ double mutants considerably increased DHS and So production while decreasing GlcCers. The production yields of LCBs from the Ylsur2Δsld1Δ/maCER1 strain increased in proportion to the C/N ratio in the N-source optimized medium, leading to production of 1.4 g/L non-acetylated DHS at the 5 L fed-batch fermentation with glucose feeding. This study highlights the feasibility of using the engineered Y. lipolytica strains as a cell factory for valuable sphingolipid derivatives for pharmaceuticals, cosmeceuticals, and nutraceuticals.

Functional diversity of Bisifusarium domesticum and the newly described Nectriaceae cheese-associated species

Bisifusarium domesticum is among the main molds used during cheese-making for its "anticollanti" property that prevents the sticky smear defect of some cheeses. Previously, numerous cheese rinds were sampled to create a working collection and not only did we isolate B. domesticum but we observed a completely unexpected diversity of "Fusarium-like" fungi belonging to the Nectriaceae family. Four novel cheese-associated species belonging to two genera were described: Bisifusarium allantoides, Bisifusarium penicilloides, Longinectria lagenoides, and Longinectria verticilliformis. In this study, we thus aimed at determining their potential functional impact during cheese-making by evaluating their lipolytic and proteolytic activities as well as their capacity to produce volatile (HS-Trap GC-MS) and non-volatile secondary metabolites (HPLC & LC-Q-TOF). While all isolates were proteolytic and lipolytic, higher activities were observed at 12 °C for several B. domesticum, B. penicilloides and L. lagenoides isolates, which is in agreement with typical cheese ripening conditions. Using volatilomics, we identified multiple cheese-related compounds, especially ketones and alcohols. B. domesticum and B. penicilloides isolates showed higher aromatic potential although compounds of interest were also produced by B. allantoides and L. lagenoides. These species were also lipid producers. Finally, an untargeted extrolite analysis suggested a safety status of these strains as no known mycotoxins were produced and revealed the production of potential novel secondary metabolites. Biopreservation tests performed with B. domesticum suggested that it may be an interesting candidate for biopreservation applications in the cheese industry in the future.

Quantitative metabolic analysis of plasma extracellular vesicles for the diagnosis of severe acute pancreatitis

BACKGROUND

Severe acute pancreatitis (SAP) is the most common gastrointestinal disease and is associated with unpredictable seizures and high mortality rates. Despite improvements in the treatment of acute pancreatitis, the timely and accurate diagnosis of SAP remains highly challenging. Previous research has shown that extracellular vesicles (EVs) in the plasma have significant potential for the diagnosis of SAP since the pancreas can release EVs that carry pathological information into the peripheral blood in the very early stages of the disease. However, we know very little about the metabolites of EVs that might play a role in the diagnosis of SAP.

METHODS

Here, we performed quantitative metabolomic analyses to investigate the metabolite profiles of EVs isolated from SAP plasma. We also determined the metabolic differences of EVs when compared between healthy controls, patients with SAP, and those with mild acute pancreatitis (MAP).

RESULTS

A total of 313 metabolites were detected, mainly including organic acids, amino acids, fatty acids, and bile acids. The results showed that the metabolic composition of EVs derived from SAP and MAP was significantly different from those derived from healthy controls and identified specific differences between EVs derived from patients with SAP and MAP. On this basis, we identified four biomarkers from plasma EVs for SAP detection, including eicosatrienoic acid (C20:3), thiamine triphosphate, 2-Acetylfuran, and cis-Citral. The area under the curve (AUC) was greater than 0.95 for both discovery (n = 30) and validation (n = 70) sets.

CONCLUSIONS

Our data indicate that metabolic profiling analysis of plasma EVs and the screening of potential biomarkers are of significant potential for improving the early diagnosis and severity differentiation of acute pancreatitis.

Metabolomic-based clinical studies and murine models for acute pancreatitis disease: A review

Acute pancreatitis (AP) is one of the most common gastroenterological disorders requiring hospitalization and is associated with substantial morbidity and mortality. Metabolomics nowadays not only help us to understand cellular metabolism to a degree that was not previously obtainable, but also to reveal the importance of the metabolites in physiological control, disease onset and development. An in-depth understanding of metabolic phenotyping would be therefore crucial for accurate diagnosis, prognosis and precise treatment of AP. In this review, we summarized and addressed the metabolomics design and workflow in AP studies, as well as the results and analysis of the in-depth of research. Based on the metabolic profiling work in both clinical populations and experimental AP models, we described the metabolites with potential utility as biomarkers and the correlation between the altered metabolites and AP status. Moreover, the disturbed metabolic pathways correlated with biological function were discussed in the end. A practical understanding of current and emerging metabolomic approaches applicable to AP and use of the metabolite information presented will aid in designing robust metabolomics and biological experiments that result in identification of unique biomarkers and mechanisms, and ultimately enhanced clinical decision-making.

Exploiting the Diversity of Saccharomycotina Yeasts To Engineer Biotin-Independent Growth of Saccharomyces cerevisiae

The reported metabolic engineering strategy to enable optimal growth in the absence of biotin is of direct relevance for large-scale industrial applications of S. cerevisiae. Important benefits of biotin prototrophy include cost reduction during the preparation of chemically defined industrial growth media as well as a lower susceptibility of biotin-prototrophic strains to contamination by auxotrophic microorganisms. The observed oxygen dependency of biotin synthesis by the engineered strains is relevant for further studies on the elucidation of fungal biotin biosynthesis pathways.

Biotin, an important cofactor for carboxylases, is essential for all kingdoms of life. Since native biotin synthesis does not always suffice for fast growth and product formation, microbial cultivation in research and industry often requires supplementation of biotin. De novo biotin biosynthesis in yeasts is not fully understood, which hinders attempts to optimize the pathway in these industrially relevant microorganisms. Previous work based on laboratory evolution of Saccharomyces cerevisiae for biotin prototrophy identified Bio1, whose catalytic function remains unresolved, as a bottleneck in biotin synthesis. This study aimed at eliminating this bottleneck in the S. cerevisiae laboratory strain CEN.PK113-7D. A screening of 35 Saccharomycotina yeasts identified six species that grew fast without biotin supplementation. Overexpression of the S. cerevisiaeBIO1 (ScBIO1) ortholog isolated from one of these biotin prototrophs, Cyberlindnera fabianii, enabled fast growth of strain CEN.PK113-7D in biotin-free medium. Similar results were obtained by single overexpression of C. fabianii BIO1 (CfBIO1) in other laboratory and industrial S. cerevisiae strains. However, biotin prototrophy was restricted to aerobic conditions, probably reflecting the involvement of oxygen in the reaction catalyzed by the putative oxidoreductase CfBio1. In aerobic cultures on biotin-free medium, S. cerevisiae strains expressing CfBio1 showed a decreased susceptibility to contamination by biotin-auxotrophic S. cerevisiae. This study illustrates how the vast Saccharomycotina genomic resources may be used to improve physiological characteristics of industrially relevant S. cerevisiae.

IMPORTANCE The reported metabolic engineering strategy to enable optimal growth in the absence of biotin is of direct relevance for large-scale industrial applications of S. cerevisiae. Important benefits of biotin prototrophy include cost reduction during the preparation of chemically defined industrial growth media as well as a lower susceptibility of biotin-prototrophic strains to contamination by auxotrophic microorganisms. The observed oxygen dependency of biotin synthesis by the engineered strains is relevant for further studies on the elucidation of fungal biotin biosynthesis pathways.

Effect of the multifunctional cosmetic ingredient sphinganine on hair loss in males and females with diffuse hair reduction

Sphingolipids are well known to promote keratinocyte differentiation and to induce ceramide production. In addition, they show anti-inflammatory and antimicrobial activities. Thus, the aim of this study is to investigate the potential effect of sphinganine on prolonging the hair anagen rate and improving the overall hair quality and scalp health. The inhibitory potential of sphinganine toward 5-α-reductase was studied using an in vitro assay. The stimulation of the antimicrobial peptide HBD2 by sphinganine was measured by real-time polymerase chain reaction and immunostaining. Sphinganine bioavailability was studied ex vivo using a pig skin model. A placebo-controlled, double-blind study was designed to evaluate the efficacy of sphinganine on hair loss and hair/scalp quality in vivo. In vitro results showed that sphinganine is a potent inhibitor of 5-α-reductase type I that prevents the conversion of testosterone to dihydrotestosterone, a key factor of androgenetic male baldness. In vivo results demonstrated efficacy in reducing non-illness-related hair loss among males. In terms of expert rating, all hair quality and scalp parameters improved after application of sphinganine. Improved scalp health might be linked to the observed increase of the antimicrobial peptide HBD2. Thus, sphinganine is well suited as a topical alternative for the improvement of scalp health and hair quality and anti-hair loss application.

Serum Metabonomics of Mild Acute Pancreatitis

BACKGROUND

Mild acute pancreatitis (MAP) is a common acute abdominal disease, and exhibits rising incidence in recent decades. As an important component of systemic biology, metabonomics is a new discipline developed following genomics and proteomics. In this study, the objective was to analyze the serum metabonomics of patients with MAP, aiming to screen metabolic markers with potential diagnostic values.

METHODS

An analysis platform with ultra performance liquid chromatography-high-resolution mass spectrometry was used to screen the difference metabolites related to MAP diagnosis and disease course monitoring.

RESULTS

A total of 432 endogenous metabolites were screened out from 122 serum samples, and 49 difference metabolites were verified, among which 12 difference metabolites were identified by nonparametric test. After material identification, eight metabolites exhibited reliable results, and their levels in MAP serum were higher than those in healthy serum. Four metabolites exhibited gradual downward trend with treatment process going on, and the differences were statistically significant (P < 0.05).

CONCLUSION

Metabonomic analysis has revealed eight metabolites with potential diagnostic values toward MAP, among which four metabolites can be used to monitor the disease course.