Vanillin-bioconversion and bioengineering of the most popular plant flavor and its de novo biosynthesis in the vanilla orchid

Hydroxybenzoic acids: Microbial metabolism, pathway engineering and products

Hydroxybenzoic acids (HBAs) are plant secondary metabolites exhibiting antioxidant, antiviral, anticancer and antibacterial activities. A high and constantly increasing demand for these compounds underlines the need for novel and efficient production methods, as commonly applied plant extraction and chemical synthesis approaches are susceptible to low yields and are environmentally hazardous. Switching to biotechnology and replacing petroleum-based chemicals has potential to improve eco-efficiency in sustainable bioeconomy. With the increased focus on the production of materials using renewable resources and bio-based feedstocks, microbial fermentation and engineering drives the development and optimization of sustainable bioproduction. This systematic review summarizes current knowledge of microbial HBAs metabolism and biosynthesis. Here, the existing challenges are highlighted and the potential strategies for improved microbial production of HBAs are identified. Key aspects of HBAs metabolism and complexity of the factors related to bacterial strain selection, titer, and bioprocess strategy are examined. The opportunities of HBAs bioproduction using engineered microbial cell factories are discussed in detail and insights for synthesis improvement are presented.

Influence of Traditional Vanilla Curing on Its Physicochemical Properties and Aromatic Profile

Vanilla is native to Mexico and has social-cultural and economic importance. It is sensory characteristics are developed during the curing process, which is associated with the region where it is carried out since the know-how of each locality is involved. In this sense, this work aimed to evaluate the influence of the curing process. Four different processes from four regions (SJA, SLP, CQ and EPM) were considered, taking into account two curing conditions. Additionally, sample control was considered. The moisture content, protein, ether extract, ash and pH were analyzed. The aromatic profile was evaluated by the RATA methodology and liking level. Except for ash content, the process influenced the other physicochemical parameters. The moisture contents of SLP and CQ samples from Period 1, as well as SLP samples from Period 2, comply with the current Mexican Standard. SJA vanilla was "slightly" accepted in both periods, surpassing the control sample. In contrast, the CQ sample was the least preferred. Thirty-five aromatic descriptors were generated. At the sensory level, a clear separation of vanillas was observed according to the type of curing. The attributes described included caramel, dry fruit, fruity, honey, maltol, rancid, sweet, tree bark, vanilla and ashes, which boosted the liking level. On the other hand, the descriptors chemical, moisture, dairy, spicy, wood and lipids had a negative effect, proving that these factors can alter the aromatic balance, giving an unpleasant smell and reducing preference. It was confirmed that the curing process influences physicochemical parameters, the aromatic profile and the liking level. However, it would be necessary to consider other variables.

Production of Vanillin From Ferulic Acid by Pseudomonas putida KT2440 Using Metabolic Engineering and In Situ Product Recovery

Vanillin is the most in-demand flavouring compound in the world and because vanillin extracted from vanilla pods cannot meet the global demand, most vanillin on the market today is chemically synthesised. Increasing demands by consumers for natural ingredients have inspired efforts to develop vanillin derived from microbial sources. These efforts have been challenged by low titers, likely caused by the toxicity of vanillin to most microbial biocatalysts. In this study, we engineered a Pseudomonas putida KT2440-derived strain that accumulated vanillin from ferulic acid to 0.64 g/L. To increase the overall titre, we applied a hydrophobic polystyrene-based resin to vanillin-accumulating cultures, which enabled an increase in total vanillin recovery to an apparent titre of 3.35 g/L. This study demonstrates that P. putida can accumulate vanillin from ferulic acid to higher titers when vanillin is removed from the cultivation medium, mitigating its toxicity.

Microbial cell factories for bioconversion of lignin to vanillin - Challenges and opportunities: A review

The bioconversion of lignin into vanillin via microbial cell factories offers a promising and sustainable route for producing high-value aromatic compounds from the abundant and underutilized byproducts of plant biomass. This review comprehensively explores the synthesis, structural characteristics, and diverse industrial applications of lignin, while addressing the inherent challenges posed by its complex structure in bioconversion processes. It examines the potential of microbial cell factories for lignin degradation, emphasizing the latest advancements in genetic engineering and metabolic optimization strategies that enhance microbial efficiency in lignin degradation and vanillin biosynthesis. It further assesses the economic feasibility of lignin-to-vanillin conversion by discussing key factors influencing cost-effectiveness and scalability, highlighting the transformative potential for producing high-value aromatic compounds in an environmentally sustainable manner. The review also highlights ongoing research efforts to develop robust microbial strains and optimize metabolic pathways for improved vanillin yield. By integrating multidisciplinary approaches, this review highlights the transformative potential of microbial cell factories to valorize lignin, offering a sustainable pathway for the production of vanillin and related aromatic compounds.

Dietary essential oil components: A systematic review of preclinical studies on the management of gastrointestinal diseases

BACKGROUND

The gut is responsible for the digestion and absorption of nutrients, immune regulation, and barrier function. However, factors like poor diet, stress, and infection, can disrupt the balance of the gut microbiota and lead to intestinal inflammation and dysfunction.

PURPOSE

This systematic review aims to evaluate the effects of dietary plants-derived essential oil components on gut health and intestinal functions in animal models.

METHODS

The literature was gathered from the Scopus, Web of Science, PubMed, and Embase databases by using related search terms, such as "dietary plants", "dietary sources", "essential oils", "gut health", "intestine", "anti-inflammatory", "antioxidant", and "gut microbiota".

RESULTS

The results indicate that plant-derived dietary essential oil components, such as butyrolactone-I, carvacrol, cinnamaldehyde, citral, D-limonene, eugenol, farnesol, geraniol, indole, nerolidol, oleic acid, thymol, trans-anethole, vanillin, α-bisabolol, α-linolenic acid, α-pinene, α-terpineol, β-carotene, β-caryophyllene, and β-myrcene have been found to regulate gut health by influencing vital signalling pathways associated with inflammation. Dietary essential oil components modulate the expression of tumor necrosis factor alpha, interleukin 1 beta (IL-1β), interleukin (IL)-6, IL-10, inducible nitric oxide synthase, cyclooxygenase-2, toll-like receptor-4, matrix metalloproteinase, and interferon gamma in mitigating gut inflammation. The primary signalling molecules controlled by these molecules were AMP-activated protein kinase (AMPK), protein kinase B, extracellular signal-regulated kinase, c-Jun N-terminal kinase, mitogen-activated protein kinase, myeloid differentiation primary response 88, nuclear factor erythroid-2-related factor-2, and phosphoinositide 3-kinase (PI3K). Moreover, these phytochemicals have been shown to improve glucose homeostasis by regulating glucose transporter 4, glucagon-like peptide-1, peroxisome proliferator-activated receptor gamma, nuclear factor kappa B, AMPK, PI3K, and uncoupling protein-1. They can also reduce thiobarbituric acid reactive substance, malondialdehyde, and oxidative stress and enhance superoxide dismutase, catalase, and glutathione peroxidase levels.

CONCLUSION

In conclusion, dietary plants-derived essential oil components have the potential to mitigate inflammation and oxidative stress in the gut. However, additional clinical investigations are necessary to confirm their complete potential in improving human gut health functions.

Production, extraction, and authentication of natural and non-natural vanillin. A comprehensive review and economic future biotechnology perspectives

Vanillin is a chief flavoring agent owing to its immense popularity in food, beverage, and pharmaceutical industries. This study holistically dissects vanillin quality control approaches that include conventional, hyphenated, and sensory analyses. Markers to differentiate between authentic, synthetic, and adulterated vanilla are highlighted using hyphenated techniques. Carbon isotope ratio range appears of potential to identify vanillin originating from biosynthetic (C3 plant), synthetic (petroleum) sources, or vanilla pods. Novel extraction methods typically provide greater selectivity, higher purity, shorter extraction times, and ecofriendly attributes compared to conventional methods. Best methods include supercritical fluids (SCF) or natural deep eutectic solvents (NADES) that promoted higher yield of vanillin. The review also highlights the promising avenue of biotransformation, the safest technique for the production of vanilla flavor components, tackling current challenges and emphasizing its potential to meet the market needs for authenticated and high-quality yields of vanillin.

Effect of different killing methods during curing on the phytochemical and bacterial composition of Vanilla planifolia using multi-omic approaches

Vanilla planifolia Jacks. ex Andrews, is cultivated for its aromatic pods, obtaining the primary source of vanillin, a molecule valued for its flavor and bioactivity. Mexico ranks among the top five global producers, and Papantla, Veracruz, contributes 70 % of national production. Developing vanilla's characteristic aroma involves a curing process composed of killing, sweating, drying, and conditioning, which enzymatic reactions and microbial activity play essential roles. This study assessed the impact of four killing treatments: microwave, hot water immersion, sonication, and freezing on the phenolic composition and bacterial communities in vanilla curing through metabolomic and 16S sequencing approaches. Freezing treatment resulted in the most substantial changes in phenolic profiles, including higher vanillin concentrations. Bacillus was the dominant bacterial genus, with hot water immersion and sonication showing the greatest α-diversity. These findings underscore the value of omic sciences in refining curing processes, enabling producers to achieve higher-quality vanilla through more efficient and technical methods.

Uncovering the sensory properties of commercial and experimental clean label almond milks

Almond milk is the largest category of plant-based milk alternatives in the United States, and it is manufactured by suspending ground almond paste in water. Nevertheless, this method limits the amount of almonds that can be added to almond milk, and most almond milks on the market have low protein despite almonds themselves being nutritionally dense. The use of sustainable aqueous and enzyme-assisted aqueous extraction processes offers an alternative method for producing almond milks with enhanced nutritional content. However, it is currently unclear how the sensory properties of such milks compare to those of commercial almond milks. In this study, we conducted a sensory descriptive analysis with 14 trained panelists on 12 commercial almond milk samples and 14 formulated ones (seven aqueous and seven enzyme-assisted aqueous extracted milks). The purpose of this study was to understand how sensorially diverse commercial almond milks are, as well as to determine how aqueous and enzyme-assisted aqueous extracted almond milks compare to commercial methods. We found that formulated samples were significantly different from commercial products, and that all commercial products could be distinguished from each other. Furthermore, commercial milks were more differentiated than were formulated samples. Given the sensory diversity of almond milks on the market, this study suggests that there is potential for introducing new products in the almond milk category. Finally, this study also showed that descriptive analysis can be successfully conducted with two distinct groups of products in the same panel. PRACTICAL APPLICATION: The almond milk category is highly diverse in terms of sensory characteristics, presenting opportunities to develop new products that offer unique sensory experiences distinct from those of existing products.

Geographic origin characterization of Brazilian green coffee beans via untargeted metabolomics

Coffee is a widely popular beverage worldwide, known for its distinct sensory properties which are greatly affected by geographical origin. Herein, we performed an untargeted metabolomic evaluation of green coffee beans (n = 40) from four different regions in Brazil: Cerrado Mineiro, Sul de Minas, Caparaó, and Mogiana Paulista; by using UHPLC-HRMS (ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry). The most significant metabolites responsible for coffee characterization were theobromine, zeatin, phenylacetaldehyde, 2-acetyl-1-pyrroline, chlorogenic acids, ferulic acid, p-coumaric acid, abscisic acid, and jasmonic acid. Our findings demonstrate that the green coffee cultivated in Cerrado Mineiro, the most valuable among the four samples evaluated, exhibits a unique and typical metabolite profile, setting it apart from the coffee beans grown in other regions. Finally, the findings reported may be relevant for coffee producers in the Cerrado Mineiro area, as they contribute to establishing a certificate of origin for their high-quality product.

Genetic Engineering Approaches for the Microbial Production of Vanillin

Vanilla flavour is widely used in various industries and is the most broadly used flavouring agent in the food industry. The demand for this flavour is, therefore, extremely high, yet vanilla bean extracts can only meet about 1% of the overall demand. Vanillin, the main constituent of vanilla flavour, can easily be obtained through chemical synthesis. Nonetheless, consumer demands for natural products and environmentally friendly industrial processes drive the development of biotechnological approaches for its production. Some microorganisms can naturally produce vanillin when fed with various substrates, including eugenol, isoeugenol, and ferulic acid. The characterisation of the genes and enzymes involved in these bioconversion pathways, as well as progress in the understanding of vanillin biosynthesis in Vanilla orchids, allowed the development of genetic engineering and synthetic biology approaches to increase vanillin production in naturally vanillin-producing microorganisms, or to implement novel vanillin biosynthetic pathways in microbial chassis. This review summarises and discusses these genetic engineering and synthetic biology approaches for the microbial production of vanillin.

Optimization of vanillin biosynthesis in Escherichia coli K12 MG1655 through metabolic engineering

Vanillin is an important flavouring agent applied in food, spices, pharmaceutical industries and other fields. Microbial biosynthesis of vanillin is considered a sustainable and economically feasible alternative to traditional chemical synthesis. In this study, Escherichia coli K12 MG1655 was used for the de novo synthesis of VAN by screening highly active carboxylic acid reductases and catechol O-methyltransferases, optimising the protocatechuic acid pathway, and regulating competitive metabolic pathways. Additionally, major alcohol by-products were identified and decreased by deleting three endogenous aldo-keto reductases and three alcohol dehydrogenases. Finally, a highest VAN titer was achieved to 481.2 mg/L in a 5 L fermenter from glucose. This work provides a valuable example of pathway engineering and screens several enzyme variants for the first time in E. coli.

Metabolic-Engineering Approach to Enhance Vanillin and Phenolic Compounds in Ocimum Sanctum (CIM-Angana) via VpVAN Overexpression

Transgenic Ocimum sanctum plants were engineered to produce vanillin by overexpressing the VpVAN gene using Agrobacterium-mediated transformation. Positive transformants developed shoots within 4-5 weeks and were transferred to a root induction medium and four independent transformants with no observed adverse effects were kept for anlysis. Quantitative RT-PCR indicated significantly higher VpVAN expression in transgenic lines AG_3 and AG_1, impacting the phenylpropanoid pathway and phenolic compound accumulation. Molecular docking studies indicated ferulic acid's higher binding affinity to vanillin synthase than eugenol. LC-MS/MS analysis revealed a marked increase in vanillin production in transgenic lines compared to wild type, with AG_3 exhibiting the highest vanillin content (1.98 ± 0.0047 mg/g extract) and AG_1 following (1.49 ± 0.0047 mg/g extract). AG_3 also showed elevated levels of benzoic acid, 4-hydroxy benzyl alcohol, and ferulic acid. This study highlights the potential of metabolic engineering in O. sanctum for enhanced vanillin production, suggesting pathways for large-scale production of natural vanillin and other valuable compounds in transgenic plants.

Metabolic engineering of hairy root cultures in Beta vulgaris for enhanced production of vanillin, 4-hydroxybenzoic acid, and vanillyl alcohol

The flavor of vanilla is a complex blend of compounds, with vanillin as the most prominent, along with vanillyl alcohol and 4-hydroxybenzoic acid. Natural vanillin extracted from vanilla beans is expensive, so researchers use heterologous synthesis to produce nature-identical vanillin in plant hosts. Consequently, alternative traditional farming and gathering methods are required to bridge the significant disparity between supply and demand. The current research successfully developed a method to induce hairy root formation from leaves. It integrated the Vanillin synthase (VpVAN) gene into transgenic hairy root lines of Beta vulgaris, synthesizing vanillin-related compounds. The presence of the VpVAN gene in transgenic roots was confirmed using PCR analysis. Additionally, RT-qPCR analysis demonstrated the expression of the VpVAN gene in the transgenic root lines. The transgenic hairy root clones H1, H2, and H5 showed enhanced vanillin production, vanillyl alcohol, and 4-hydroxybenzoic acid. Elicitation with methyl jasmonate (MJ) and salicylic acid (SA) further improved the production of these compounds in B. vulgaris hairy roots. The maximum hairy root biomass was observed after 60 days, with the maximum synthesis of vanillin and 4-hydroxybenzoic acid obtained from hairy root clones H5 and HR2, respectively. Vanillyl alcohol HR2 was obtained on the 45th day of cultivation. Elicitation with wound-associated hormone methyl jasmonate and salicylic acid enhanced the yield of vanillin, vanillyl alcohol, and 4-hydroxybenzoic acid, with a 215-fold increase in vanillin, a 13-fold increase in vanillyl alcohol, and a 21 fold increase in 4-hydroxybenzoic acid. The study results indicate that establishing transgenic hairy root cultures with the VpVAN gene is a promising alternative method for enhancing the production of vanilla flavor compounds such as vanillin, vanillyl alcohol, and 4-hydroxybenzoic acid. A cost-effective protocol has been developed to mass-produce phenolic compounds using a hairy root culture of B. vulgaris. This approach addresses the increasing demand for these substances while reducing the cost of natural vanillin production, making it suitable for industrial-scale applications.

Pathway-Adapted Biosensor for High-Throughput Screening of O-Methyltransferase and its Application in Vanillin Synthesis

Vanillin is a widely used flavoring compound in the food, pharmaceutical, and cosmetics area. However, the biosynthesis of vanillin from low-cost shikimic acid is significantly hindered by the low activity of the rate-limiting enzyme, caffeate O-methyltransferase (COMT). To screen COMT variants with improved conversion rates, we designed a biosensing system that is adaptable to the COMT-mediated vanillin synthetic pathway. Through the evolution of aldehyde transcriptional factor YqhC, we obtained a dual-responsive variant, MuYqhC, which positively responds to the product and negatively responds to the substrate, with no response to intermediates. Using the MuYqhC-based vanillin biosensor, we successfully identified a COMT variant, Mu176, that displayed a 7-fold increase in the conversion rate compared to the wild-type COMT. This variant produced 2.38 mM vanillin from 3 mM protocatechuic acid, achieving a conversion rate of 79.33%. The enhanced activity of Mu176 was attributed to an enlarged binding pocket and strengthened substrate interaction. Applying Mu176 to Bacillus subtilis increased the level of vanillin production from shikimic acid by 2.39-fold. Further optimization of the production chassis, increasing the S-adenosylmethionine supply and the precursor concentration, elevated the vanillin titer to 1 mM, marking the highest level of vanillin production from shikimic acid in Bacillus. Our work highlights the significance of the MuYqhC-based biosensing system and the Mu176 variant in vanillin production.

Correlation of Vanillin-Induced Cytotoxicity with CYP3A-Mediated Metabolic Activation

Vanillin (VAN) is a common flavoring agent that can cause liver damage when ingested in large amounts. Nevertheless, the precise processes responsible for its toxicity remain obscure. The present research aimed to examine the metabolic activation of VAN and establish a potential correlation between its reactive metabolites and its cytotoxicity. In rat liver microsomes incubated with VAN, reduced glutathione/N-acetylcysteine (GSH/NAC), and nicotinamide adenine dinucleotide phosphate (NADPH), two conjugates formed from GSH and one conjugate derived from NAC were identified. We also discovered one GSH conjugate in both the bile obtained from rats and the rat primary hepatocytes that were subjected to VAN exposure. Additionally, the NAC conjugate exerted in the urine of VAN-treated rats was observed. These results indicate that a quinone intermediate was produced from VAN both in vitro and in vivo. Next, we identified CYP3A as the main enzyme that initiated the bioactive pathway of VAN. After the activity of CYP3A was selectively inhibited by ketoconazole (KTZ), the generation of the GSH conjugate declined in hepatocytes exposed to VAN. Furthermore, the vulnerability to VAN-induced toxicity was alleviated by KTZ in hepatocytes. Thus, we propose that the cytotoxicity of VAN may derive from metabolic activation triggered by CYP3A.

Molecular Aroma Composition of Vanilla Beans from Different Origins

The demand for natural Vanilla has increased rapidly, creating the need for more potential sources of high-quality Vanilla essence. Understanding the geographical influences on the aroma profile of Vanilla is essential. This study demonstrates the first comparative analysis of odorant compositions in the three most important Vanilla varieties: Vanilla planifolia, Vanilla pompona, and Vanilla tahitensis from different origins. Following the screening for odor-active molecules through gas chromatography-olfactometry and aroma extract dilution analysis (GC-O and AEDA), selected compounds were quantified using stable isotope dilution assays (SIDA) and their dose over threshold values (DoTs) were calculated. Vanillin was confirmed as the most important odor-active compound due to its highest DoT value, especially in the V. planifolia sample. Meanwhile, 4-methoxybenzyl alcohol and 4-methoxybenzaldehyde showed higher DoT factors than vanillin in V. pompona and partially in V. tahitensis samples. This indicates their role as discriminative odorants for these varieties. The heightened DoT values of 3-hydroxy-4,5-dimethyl-2(5H)-furanone in Uganda Vanilla samples unveil geographical influences on the odorant profile within V. planifolia species. Additionally, 2-methyl-3-(methyldithio)furan was identified for the first time in Vanilla samples with diverse DoT values from different species and origins.

Construction of a Novel Vanillin-Induced Autoregulating Bidirectional Transport System in a Vanillin-Producing E. coli Cell Factory

Vanillin is one of the world's most extensively used flavoring agents with high application value. However, the yield of vanillin biosynthesis remains limited due to the low efficiency of substrate uptake and the inhibitory effect on cell growth caused by vanillin. Here, we screened high-efficiency ferulic acid importer TodX and vanillin exporters PP_0178 and PP_0179 by overexpressing genes encoding candidate transporters in a vanillin-producing engineered Escherichia coli strain VA and further constructed an autoregulatory bidirectional transport system by coexpressing TodX and PP_0178/PP_0179 with a vanillin self-inducible promoter ADH7. Compared with strain VA, strain VA-TodX-PP_0179 can efficiently transport ferulic acid across the cell membrane and convert it to vanillin, which significantly increases the substrate utilization rate efficiency (14.86%) and vanillin titer (51.07%). This study demonstrated that the autoregulatory bidirectional transport system significantly enhances the substrate uptake efficiency while alleviating the vanillin toxicity issue, providing a promising viable route for vanillin biosynthesis.

Engineering a coenzyme-independent dioxygenase for one-step production of vanillin from ferulic acid

Vanillin is one of the world's most important flavor and fragrance compounds used in foods and cosmetics. In plants, vanillin is reportedly biosynthesized from ferulic acid via the hydratase/lyase-type enzyme VpVAN. However, in biotechnological and biocatalytic applications, the use of VpVAN limits the production of vanillin. Although microbial enzymes are helpful as substitutes for plant enzymes, synthesizing vanillin from ferulic acid in one step using microbial enzymes remains a challenge. Here, we developed a single enzyme that catalyzes vanillin production from ferulic acid in a coenzyme-independent manner via the rational design of a microbial dioxygenase in the carotenoid cleavage oxygenase family using computational simulations. This enzyme acquired catalytic activity toward ferulic acid by introducing mutations into the active center to increase its affinity for ferulic acid. We found that the single enzyme can catalyze not only the production of vanillin from ferulic acid but also the synthesis of other aldehydes from p-coumaric acid, sinapinic acid, and coniferyl alcohol. These results indicate that the approach used in this study can greatly expand the range of substrates available for the dioxygenase family of enzymes. The engineered enzyme enables efficient production of vanillin and other value-added aldehydes from renewable lignin-derived compounds.

IMPORTANCE

The final step of vanillin biosynthesis in plants is reportedly catalyzed by the enzyme VpVAN. Prior to our study, VpVAN was the only reported enzyme that directly converts ferulic acid to vanillin. However, as many characteristics of VpVAN remain unknown, this enzyme is not yet suitable for biocatalytic applications. We show that an enzyme that converts ferulic acid to vanillin in one step could be constructed by modifying a microbial dioxygenase-type enzyme. The engineered enzyme is of biotechnological importance as a tool for the production of vanillin and related compounds via biocatalytic processes and metabolic engineering. The results of this study may also provide useful insights for understanding vanillin biosynthesis in plants.

A comprehensive review of eclectic approaches to the biological synthesis of vanillin and their application towards the food sector

Vanillin, a highly regarded flavor compound, has earned widespread recognition for its natural and aromatic qualities, piquing substantial interest in the scientific community. This comprehensive review delves deeply into the intricate world of vanillin synthesis, encompassing a wide spectrum of methodologies, including enzymatic, microbial, and immobilized systems. This investigation provides a thorough analysis of the precursors of vanillin and also offers a comprehensive overview of its transformation through these diverse processes, making it an invaluable resource for researchers and enthusiasts alike. The elucidation of different substrates such as ferulic acid, eugenol, veratraldehyde, vanillic acid, glucovanillin, and C6-C3 phenylpropanoids adds a layer of depth and insight to the understanding of vanillin synthesis. Moreover, this comprehensive review explores the multifaceted applications of vanillin within the food industry. While commonly known as a flavoring agent, vanillin transcends this role by finding extensive use in food preservation and food packaging. The review meticulously examines the remarkable preservative properties of vanillin, providing a profound understanding of its crucial role in the culinary and food science sectors, thus making it an indispensable reference for professionals and researchers in these domains.

Graphical abstract

Reconstructing curcumin biosynthesis in yeast reveals the implication of caffeoyl-shikimate esterase in phenylpropanoid metabolic flux

Curcumin is a polyphenolic natural product from the roots of turmeric (Curcuma longa). It has been a popular coloring and flavoring agent in food industries with known health benefits. The conventional phenylpropanoid pathway is known to proceed from phenylalanine via p-coumaroyl-CoA intermediate. Although hydroxycinnamoyl-CoA: shikimate hydroxycinnamoyl transferase (HCT) plays a key catalysis in the biosynthesis of phenylpropanoid products at the downstream of p-coumaric acid, a recent discovery of caffeoyl-shikimate esterase (CSE) showed that an alternative pathway exists. Here, the biosynthetic efficiency of the conventional and the alternative pathway in producing feruloyl-CoA was examined using curcumin production in yeast. A novel modular multiplex genome-edit (MMG)-CRISPR platform was developed to facilitate rapid integrations of up to eight genes into the yeast genome in two steps. Using this MMG-CRISPR platform and metabolic engineering strategies, the alternative CSE phenylpropanoid pathway consistently showed higher titers (2-19 folds) of curcumin production than the conventional pathway in engineered yeast strains. In shake flask cultures using a synthetic minimal medium without phenylalanine, the curcumin production titer reached up to 1.5 mg/L, which is three orders of magnitude (∼4800-fold) improvement over non-engineered base strain. This is the first demonstration of de novo curcumin biosynthesis in yeast. Our work shows the critical role of CSE in improving the metabolic flux in yeast towards the phenylpropanoid biosynthetic pathway. In addition, we showcased the convenience and reliability of modular multiplex CRISPR/Cas9 genome editing in constructing complex synthetic pathways in yeast.

Comparison of Carbon Isotope Ratio Measurement of the Vanillin Methoxy Group by GC-IRMS and 13C-qNMR

Site-specific carbon isotope ratio measurements by quantitative 13C NMR (13C-qNMR), Orbitrap-MS, and GC-IRMS offer a new dimension to conventional bulk carbon isotope ratio measurements used in food provenance, forensics, and a number of other applications. While the site-specific measurements of carbon isotope ratios in vanillin by 13C-qNMR or Orbitrap-MS are powerful new tools in food analysis, there are a limited number of studies regarding the validity of these measurement results. Here we present carbon site-specific measurements of vanillin by GC-IRMS and 13C-qNMR for methoxy carbon. Carbon isotope delta (δ13C) values obtained by these different measurement approaches demonstrate remarkable agreement; in five vanillin samples whose bulk δ13C values ranged from -31‰ to -26‰, their δ13C values of the methoxy carbon ranged from -62.4‰ to -30.6‰, yet the difference between the results of the two analytical approaches was within ±0.6‰. While the GC-IRMS approach afforded up to 9-fold lower uncertainties and required 100-fold less sample compared to the 13C-qNMR, the 13C-qNMR is able to assign δ13C values to all carbon atoms in the molecule, not just the cleavable methoxy group.

Genome-wide identification of the glutamate receptor-like gene family in Vanilla planifolia and their response to Fusarium oxysporum infection

Glutamate receptor-like genes (GLRs) are essential for plant growth and development and for coping with environmental (biological and non-biological) stresses. In this study, 13 GLR members were identified in the Vanilla planifolia genome and attributed to two subgroups (Clade I and Clade III) based on their physical relationships. Cis-acting element analysis and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations indicated the GLR gene regulation's complexity and their functional diversity. Expression analysis revealed a relatively higher and more general expression pattern of Clade III members compared to the Clade I subgroup in tissues. Most GLRs showed significant differences in expression during Fusarium oxysporum infection. This suggested that GLRs play a critical role in the response of V. planifolia to pathogenic infection. These results provide helpful information for further functional research and crop improvement of VpGLRs.

Gamma Irradiation Promotes the Growth Rate of Thai Pigmented Rice As Well As Inducing the Accumulation of Bioactive Compounds and Carbohydrate Hydrolyzing Enzymes Inhibitors (α-Glucosidase and α-Amylase) under Salt Conditions

Rice contains many bioactive compounds that perform various biological activities. Some of these compounds have been identified as α-glucosidase and α-amylase inhibitors, including guaiacol, vanillin, methyl vanillate, vanillic acid, syringic acid, and 2-pentyl furan. In this study, we assessed the growth rate, photosynthetic pigment content, phenolic content, and flavonoid content of gamma-irradiated Thai pigmented rice. Bioactive components of gamma-irradiated rice that had been subjected to salt treatment were also investigated. The findings showed that production of photosynthetic pigments, which are associated with plant growth, was induced by low gamma exposure. Phenolic and flavonoid content of rice was increased after gamma irradiation at 5 to 1,000 Gy. Both gamma irradiation and the salt conditions changed the quantity of vanillin, methyl vanillate, and vanillic acid in the rice. However, at a salt concentration of 40 mM, the salt stress had more of an effect than the gamma dosage. However, the high concentrations of methyl vanillate and vanillic acid detected in the rice under salt conditions were ameliorated by gamma irradiation. Guaiacol served as the substrate of guaiacol peroxidase for catalyzed reactive oxygen species, as evidenced by the observation that the guaiacol content of rice decreased between increased gamma dosages. A gamma dose of 40 to 1,000 Gy resulted in the production of syringic acid. Under salt stress, syringic acid buildup was also seen to be ameliorated by gamma irradiation. In comparison to salt conditions, particularly for 20 mM salt, gamma irradiation had less of an impact on the 2-pentyl furan in rice.

Identification of ethyl vanillin in strawberry (Fragaria × ananassa) using a targeted metabolomics strategy: From artificial to natural

Improving flavor can be an important goal of strawberry through breeding that is enhanced through the accurate identification and quantification of flavor compounds. Herein, a targeted metabolomics strategy was developed using liquid-liquid extraction, an in-house standard database, and GC-MS/MS analysis. The database consisted of key food odorants (KFOs), artificial flavor compounds (AFCs) and volatiles. A total of 131 flavor compounds were accurately identified in Medallion® 'FL 16.30-128' strawberry. Importantly, ethyl vanillin was identified for the first time in natural food. Multiple techniques, including GC-MS, GC-MS/MS and UPLC-MS/MS were applied to ensure the identification. The ethyl vanillin in the Medallion® samples were determined in a range of concentrations from 0.070 ± 0.0006 µg/kg to 0.1372 ± 0.0014 µg/kg by using stable isotope dilution analysis. The identification of ethyl vanillin in strawberry implys the future commercial use a natural flavor compound and the potential to identify genes and proteins associated with its biosynthesis.

Carbon and Oxygen Isotopic Ratio Analysis by FT ICR MS for Natural Vanillin Authentication

Vanillin is the main component of vanilla flavor and is naturally produced from an orchid. However, due to the high cost and time-intensive nature of cultivating natural vanilla pods, most of the vanillin is mainly artificially manufactured. Existing methodologies, such as isotope ratio mass spectrometry (IRMS) and site-specific natural isotopic fractionation by nuclear magnetic resonance (SNIF-NMR), are employed to differentiate natural vanillin from other sources based on carbon and hydrogen isotope measurements. Nevertheless, these methods have limitations, as the carbon isotopic ratio can be counterfeited by adding commercially available enriched vanillin. For this research, we purified 1 mg of vanillin from pods from various geographical and botanical sources. We developed a novel method for analyzing 13C/12C and 18O/16O isotopic ratios of vanillin using direct injection analysis coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). This innovative approach enables the examination of bulk vanillin carbon and oxygen isotopic ratios, as well as specific molecular fragments. By analyzing a characteristic vanillin fragment that provides site-specific 18O/16O isotopic ratio data, we achieved superior clustering and discrimination of samples based on their botanical source and geographical origin. Our proposed method holds significant potential for vanillin authentication and can be performed using a mere 20 μg of pure vanillin in just 10 min of analysis time. Subsequent research should focus on acquiring additional vanillin samples from diverse botanical, geographical, and biosynthetic origins while exploring various isotopic ratios to further enhance the reproducibility and reliability of this methodology.

Natural complex substances: From molecules to the molecular complexes. Analytical and technological advances for their definition and differentiation from the corresponding synthetic substances

Natural complex substances (NCSs) are a heterogeneous family of substances that are notably used as ingredients in several products classified as food supplements, medical devices, cosmetics and traditional medicines, according to the correspondent regulatory framework. The compositions of NCSs vary widely and hundreds to thousands of compounds can be present at the same time. A key concept is that NCSs are much more than the simple sum of the compounds that constitute them, in fact some emerging phenomena are the result of the supramolecular interaction of the constituents of the system. Therefore, close attention should be paid to produce and characterize these systems. Today many natural compounds are produced by chemical synthesis and are intentionally added to NCSs, or to formulated natural products, to enhance their properties, lowering their production costs. Market analysis shows a tendency of people to use products made with NCSs and, currently, products made with ingredients of natural origin only are not conveniently distinguishable from those containing compounds of synthetic origin. Furthermore, the uncertainty of the current European regulatory framework does not allow consumers to correctly differentiate and identify products containing only ingredients of natural origin. The high demand for specific and effective NCSs and their high-cost offer on the market, create the conditions to economically motivated sophistications, characterized by the addition of a cheap material to a more expensive one, just to increase profit. This type of practice can concern both the addition of less valuable natural materials and the addition of pure artificial compounds with the same structure as those naturally present. In this scenario, it becomes essential for producers of natural products to have advanced analytical techniques to evaluate the effective naturalness of NCSs. In fact, synthetically obtained compounds are not identical to their naturally occurring counterparts, due to the isotopic composition or chirality, as well as the presence of different trace metabolites (since pure substances in nature do not exist). For this reason, in this review, the main analytical tests that can be performed to differentiate natural compounds from their synthetic counterparts will be highlighted and the main analytical technologies will be described. At the same time, the main fingerprint techniques useful for characterizing the complexity of the NCSs, also allowing their identification and quali-quantitative evaluation, will be described. Furthermore, NCSs can be produced through different manufacturing processes, not all of which are on the same level of quality. In this review the most suitable technologies for green processes that operate according to physical extraction principles will be presented, as according to the authors they are the ones that come closest to creating more life-cycle compatible NCSs and that are well suited to the European green deal, a strategy with the aim of transforming the EU into a sustainable and resource-efficient society by 2050.

The multifactorial role of vanillin in amelioration of aluminium chloride and D-galactose induced Alzheimer's disease in mice

The onset and progression of Alzheimer's disease (AD) are influenced by a variety of factors. These include oxidative stress, overexpression of acetylcholinesterase (AChE), depletion of acetylcholine levels, increased beta-secretase mediated conversion of Amyloid Precursor Protein (APP) to Amyloid Beta (Abeta), accumulation of Abeta oligomers, decrease in Brain Derived Neurotrophic factor (BDNF) and accelerated neuronal apoptosis due to elevated levels of caspase-3. The currently available therapeutic approaches are inadequate in affecting these pathological processes except maybe the overexpression of AChE (AChE inhibitors like donepezil, rivastigmine). There is an urgent need to develop disease modifying pharmacotherapeutic interventions which have appreciable safety and cost effectiveness. From previously reported in vitro studies and a preliminary assessment of neuroprotective effect in scopolamine induced dementia-like cognitive impairment in mice, vanillin has been used as the compound of interest in the present study. Vanillin, a phytoconstituent, has been used in humans, safely, in the form of a flavouring agent for various foods, beverages, and cosmetics. Owing to its chemical nature i.e. being a phenolic aldehyde, it has an additional antioxidant property that is congruent to the desirable characteristics that are sought in a suitable novel anti-AD agent. In our study, vanillin proved to have a nootropic effect in healthy Swiss albino mice as well as an ameliorative effect in aluminium chloride and D-galactose induced AD model in mice. Apart from tackling oxidative stress, vanillin was found to reduce the levels of AChE, beta secretase, caspase-3, enhance degradation of Abeta plaques and elevate the levels of BDNF, in cortical and hippocampal regions. Vanillin is a promising candidate for being incorporated into the search for safe and effective anti-AD molecules. However, further research might be needed to warrant its application clinically.

Comprehensive phylogenetic analyses of Orchidaceae using nuclear genes and evolutionary insights into epiphytism

Orchidaceae (with >28,000 orchid species) are one of the two largest plant families, with economically and ecologically important species, and occupy global and diverse niches with primary distribution in rainforests. Among orchids, 70% grow on other plants as epiphytes; epiphytes contribute up to ~50% of the plant diversity in rainforests and provide food and shelter for diverse animals and microbes, thereby contributing to the health of these ecosystems. Orchids account for over two-thirds of vascular epiphytes and provide an excellent model for studying evolution of epiphytism. Extensive phylogenetic studies of Orchidaceae and subgroups have ;been crucial for understanding relationships among many orchid lineages, although some uncertainties remain. For example, in the largest subfamily Epidendroideae with nearly all epiphytic orchids, relationships among some tribes and many subtribes are still controversial, hampering evolutionary analyses of epiphytism. Here we obtained 1,450 low-copy nuclear genes from 610 orchid species, including 431 with newly generated transcriptomes, and used them for the reconstruction of robust Orchidaceae phylogenetic trees with highly supported placements of tribes and subtribes. We also provide generally well-supported phylogenetic placements of 131 genera and 437 species that were not sampled by previous plastid and nuclear phylogenomic studies. Molecular clock analyses estimated the Orchidaceae origin at ~132 million years ago (Ma) and divergences of most subtribes from 52 to 29 Ma. Character reconstruction supports at least 14 parallel origins of epiphytism; one such origin was placed at the most recent common ancestor of ~95% of epiphytic orchids and linked to modern rainforests. Ten occurrences of rapid increase in the diversification rate were detected within Epidendroideae near and after the K-Pg boundary, contributing to ~80% of the Orchidaceae diversity. This study provides a robust and the largest family-wide Orchidaceae nuclear phylogenetic tree thus far and new insights into the evolution of epiphytism in vascular plants.

A small molecule potent IRAK4 inhibitor abrogates lipopolysaccharide-induced macrophage inflammation in-vitro and in-vivo

Increasing evidence supports vanillin and its analogs as potent toll-like receptor signaling inhibitors that strongly attenuate inflammation, though, the underlying molecular mechanism remains elusive. Here, we report that vanillin inhibits lipopolysaccharide (LPS)-induced toll-like receptor 4 activation in macrophages by targeting the myeloid differentiation primary-response gene 88 (MyD88)-dependent pathway through direct interaction and suppression of interleukin-1 receptor-associated kinase 4 (IRAK4) activity. Moreover, incubation of vanillin in cells expressing constitutively active forms of different toll-like receptor 4 signaling molecules revealed that vanillin could only able to block the ligand-independent constitutively activated IRAK4/1 or its upstream molecules-associated NF-κB activation and NF-κB transactivation along with the expression of various proinflammatory cytokines. A significant inhibition of LPS-induced IRAK4/MyD88, IRAK4/IRAK1, and IRAK1/TRAF6 association was evinced in response to vanillin treatment. Furthermore, mutations at Tyr262 and Asp329 residues in IRAK4 or modifications of 3-OMe and 4-OH side groups in vanillin, significantly reduced IRAK4 activity and vanillin function, respectively. Mice pretreated with vanillin followed by LPS challenge markedly impaired LPS-induced IRAK4 activation and inflammation in peritoneal macrophages. Thus, the present study posits vanillin as a novel and potent IRAK4 inhibitor and thus providing an opportunity for its therapeutic application in managing various inflammatory diseases.

Lactic acid bacteria as a tool for biovanillin production: A review

Vanilla is the most commonly used natural flavoring agent in industries like food, flavoring, medicine, and fragrance. Vanillin can be obtained naturally, chemically, or through a biotechnological process. However, the yield from vanilla pods is low and does not meet market demand, and the use of vanillin produced by chemical synthesis is restricted in the food and pharmaceutical industries. As a result, the biotechnological process is the most efficient and cost-effective method for producing vanillin with consumer-demanding properties while also supporting industrial applications. Toxin-free biovanillin production, based on renewable sources such as industrial wastes or by-products, is a promising approach. In addition, only natural-labeled vanillin is approved for use in the food industry. Accordingly, this review focuses on biovanillin production from lactic acid bacteria (LAB), which is generally recognized as safe (GRAS), and the cost-cutting efforts that are utilized to improve the efficiency of biotransformation of inexpensive and readily available sources. LABs can utilize agro-wastes rich in ferulic acid to produce ferulic acid, which is then employed in vanillin production via fermentation, and various efforts have been applied to enhance the vanillin titer. However, different designs, such as response surface methods, using immobilized cells or pure enzymes for the spontaneous release of vanillin, are strongly advised.

Synthesis and virucide activity on zika virus of 1,2,3-triazole-containing vanillin derivatives

The Zika virus (ZIKV) is an arbovirus and belongs to the Flaviviridae family and Flavivirus genus, with dissemination in the Americas. In Brazil, the predominant strain is the Asian, promoting outbreaks that started in 2015 and are directly related to microcephaly in newborns and Guillain-Barré syndrome in adults. Recently, researchers identified a new African strain circulating in Brazil at the mid-end of 2018 and the beginning of 2019, with the potential to originate a new epidemic. To date, there is no approved vaccine or drug for the treatment of Zika syndrome, and the development of therapeutic alternatives to treat it is of relevance. A critical approach is to use natural products when searching for new chemical agents to treat Zika syndrome. The present investigation describes the preparation of a series of 1,2,3-triazoles derived from the natural product vanillin and the evaluation of their virucide activity. A series of fourteen derivatives were prepared via alkylation of vanillin followed by CuAAC (the copper(I)-catalyzed azide-alkyne cycloaddition) reaction. The compounds were fully characterized by infrared (I.R.), nuclear magnetic resonance (NMR), and high-resolution mass spectrometry (HRMS) techniques. The cytotoxicity of Vero cells and the effect on the Zika Virus of the vanillin derivatives were evaluated. It was found that the most effective compound corresponded to 4-((1-(4-isopropylbenzyl)-1H-1,2,3-triazol-4-yl)methoxy)-3-methoxybenzaldehyde (8) (EC₅₀ = 27.14 μM, IC₅₀ = 334.9 μM). Subsequent assessments, namely pre and post-treatment assays, internalization and adsorption inhibition assays, kinetic, electronic microscopy analyses, and zeta potential determination, revealed that compound 8 blocks the Zika virus infection in vitro by acting on the viral particle. A molecular docking study was performed, and the results are also discussed.

Production of various phenolic aldehyde compounds using the 4CL-FCHL biosynthesis platform

Vanillin (3-methoxy-4-hydroxybenzaldehyde) is one of the most important flavoring substances used in the cosmetic and food industries. Feruloyl-CoA hydratase/lyase (FCHL) is an enzyme that catalyzes the production of vanillin from feruloyl-CoA. In this study, we report kinetic parameters and biochemical properties of FCHL from Sphingomonas paucimobilis SYK-6 (SpFCHL). Also, the crystal structures of an apo-form of SpFCHL and two complexed forms with acetyl-CoA and vanillin/CoA was present. Comparing the apo structure to its complexed forms of SpFCHL, a gate loop with an "open and closed" role was observed at the entrance of the substrate-binding site. With vanillin and CoA complexed to SpFCHL, we captured a conformational change in the feruloyl moiety-binding pocket that repositions the catalytic SpFCHL^E146 and other key residues. This binding pocket does not tightly fit the vanillin structure, suggesting substrate promiscuity of this enzyme. This observation is in good agreement with assay results for phenylpropanoid-CoAs and indicates important physicochemical properties of the substrate for the hydratase/lyase reaction mechanism. In addition, we showed that various phenolic aldehydes could be produced using the 4CL-FCHL biosynthesis platform.

Vanillin Induces Relaxation in Rat Mesenteric Resistance Arteries by Inhibiting Extracellular Ca2+ Influx

Vanillin is a phenolic aldehyde, which is found in plant species of the Vanilla genus. Although recent studies have suggested that vanillin has various beneficial properties, the effect of vanillin on blood vessels has not been studied well. In the present study, we investigated whether vanillin has vascular effects in rat mesenteric resistance arteries. To examine the vascular effect of vanillin, we measured the isometric tension of arteries using a multi-wire myograph system. After the arteries were pre-contracted with high K+ (70 mM) or phenylephrine (5 µM), vanillin was administered. Vanillin induced concentration-dependent vasodilation. Endothelial denudation or treatment of eNOS inhibitor (L-NNA, 300 μM) did not affect the vasodilation induced by vanillin. Treatment of K+ channel inhibitor (TEA, 10 mM) or sGC inhibitor (ODQ, 10 μM) or COX-2 inhibitor (indomethacin, 10 μM) did not affect the vanillin-induced vasodilation either. The treatment of vanillin decreased the contractile responses induced by Ca2+ addition. Furthermore, vanillin significantly reduced vascular contraction induced by BAY K 8644 (30 nM). Vanillin induced concentration-dependent vascular relaxation in rat mesenteric resistance arteries, which was endothelium-independent. Inhibition of extracellular Ca2+ influx was involved in vanillin-induced vasodilation. Treatment of vanillin reduced phopsho-MLC20 in vascular smooth muscle cells. These results suggest the possibility of vanillin as a potent vasodilatory molecule.

Unveiling the complete genome sequence of Alicyclobacillus acidoterrestris DSM 3922T, a taint-producing strain

Several species from the Alicyclobacillus genus have received much attention from the food and beverages industries. Their presence has been co-related with spoilage events of acidic food matrices, namely fruit juices and other fruit-based products, the majority attributed to Alicyclobacillus acidoterrestris. In this work, a combination of short and long reads enabled the assembly of the complete genome of A. acidoterrestris DSM 3922T, perfecting the draft genome already available (AURB00000000), and revealing the presence of one chromosome (4,222,202 bp; GC content 52.3%) as well as one plasmid (124,737 bp; GC content 46.6%). From the 4,288 genes identified, 4,004 sequences were attributed to coding sequences with proteins, with more than 80% being functionally annotated. This allowed the identification of metabolic pathways and networks and the interpretation of high-level functions with significant reliability. Furthermore, the additional genes of interest related to spore germination, off-flavor production, namely the vdc cluster, and CRISPR arrays, were identified. More importantly, this is the first complete and closed genome sequence for a taint-producing Alicyclobacillus species and thus represents a valuable reference for further comparative and functional genomic studies.

Phytochemicals from Vanda bensonii and Their Bioactivities to Inhibit Growth and Metastasis of Non-Small Cell Lung Cancer Cells

The most prevalent lung cancer is non-small cell lung cancer (NSCLC). This lung cancer type often develops other organ-specific metastases that are critical burdens in the treatment process. Orchid species in the genus Vanda have shown their potential in folkloric medication of diverse diseases but not all its species have been investigated, and little is known about their anticancer activities against NSCLC. Here, we firstly profiled the specialized metabolites of Vanda bensonii and examined their capability to inhibit growth and metastasis of NSCLC using NCI-H460 cells as a study model. Four phytochemicals, including phloretic acid methyl ester (1), cymbinodin-A (2), ephemeranthoquinone B (3), and protocatechuic acid (4), were isolated from the whole plant methanolic extract of V. bensonii. The most distinguished cytotoxic effect on NCI-H460 cells was observed in the treatments with crude methanolic extract and compound 2 with the half maximal inhibitory concentrations of 40.39 μg mL−1 and 50.82 μM, respectively. At non-cytotoxic doses (10 μg mL−1 or 10 μM), only compound 1 could significantly limit NCI-H460 cell proliferation when treated for 48 h, while others excluding compound 4 showed significant reduction in cell proliferation after treating for 72 h. Compound 1 also significantly decreased the migration rate of NCI-H460 cells examined through a wound-healing assay. Additionally, the crude extract and compound 1 strongly affected survival and growth of NCI-H460 cells under anchorage-independent conditions. Our findings proved that natural products from V. bensonii could be promising candidates for the future pharmacotherapy of NSCLC.

Characterization of vanillin carbon isotope delta reference materials

Stable carbon isotope ratio measurements are used to investigate the provenance of vanillin. In this study, a variety of commercial vanillin samples and vanilla products were analyzed to provide a frame of reference for the variability of carbon isotope delta values in various vanillin samples, with the results ranging from -20.6 to -36.7‰ relative to the Vienna Peedee Belemnite (VPDB). We present information on the development of two synthetic vanillin reference materials, VANA-1 and VANB-1, prepared in 0.75 g units in glass vials, to be used for the calibration of carbon isotope delta measurements of vanillin and other easily combustible organic materials. Characterization of 40 vials each of VANA-1 and VANB-1 was performed by three laboratories over several measurement sequences. The certified carbon isotope delta values are -31.30 ± 0.06‰ (VANA-1) and -25.85 ± 0.05‰ (VANB-1). These uncertainties, for the 95% confidence level, include considerations for measurement uncertainty, coherence of the reference materials used for calibration, batch homogeneity, and stability during storage and transportation. The results are traceable to the VPDB through a set of nine reference materials (IAEA-CH-6, USGS65, IAEA-600, NBS22, USGS61, IAEA-603, IAEA-610, IAEA-611, and IAEA-612). For up to date certified values, users should refer to doi.org/10.4224/crm.2022.vana-1 and doi.org/10.4224/crm.2022.vanb-1.

A Diamine-Oriented Biorefinery Concept Using Ammonia and Raney Ni as a Multifaceted Catalyst

Diamines are important industrial chemicals. In this paper we outline the feasibility of lignocellulose as a source of diol-containing molecules. We also illustrate the possibility of turning these diols into their diamines in good to excellent yields. Central to these transformations is the use of commercially available Raney Ni. For diol formation, the Raney Ni engages in hydrogenation and often also demethoxylation, that way funneling multiple components to one single molecule. For diamine formation, Raney Ni catalyzes hydrogen-borrowing mediated diamination in the presence of NH₃.

Enhanced vanillin production from eugenol by Bacillus cereus NCIM-5727

Biovanillin production by a wild strain of Bacillus cereus NCIM-5727 is studied using eugenol as the precursor aiming to achieve maximum vanillin productivity. Based on shake flask optimization, molar yield and global volumetric productivity of vanillin reached up to 71.2% (6.6 gL^-1) and 0.18 g(Lh)^-1, respectively, at 36 h by resting cells of B. cereus NCIM-5727 at the optimum cell concentration of 3 gL^-1 using eugenol concentration of 10 gL^-1 at 37 ºC, buffer pH 7.0, buffer volume 10%, and shaking speed 180 rpm. Furthermore, small-scale optimization in a bioreactor at the controlled aeration rate of 0.5 Lmin^-1, agitation rate of 210 rpm, and pH 7.0 enhanced the global volumetric productivity of vanillin up to 0.28 g(Lh)^-1 at 25 h of bioconversion. The highest vanillin molar yield (75.2%) is reported using resting cells of B. cereus NCIM-5727 upon eugenol biotransformation and found stable for 10 h.

Site-specific carbon isotope measurements of vanillin reference materials by nuclear magnetic resonance spectrometry

Vanillin, one of the world's most popular flavor used in food and pharmaceutical industries, is extracted from vanilla beans or obtained (bio)-synthetically. The price of natural vanillin is considerably higher than that of its synthetic alternative which leads increasingly to counterfeit vanillin. Here, we describe the workflow of combining carbon isotope ratio combustion mass spectrometry with quantitative carbon nuclear magnetic resonance spectrometry (13C-qNMR) to obtain carbon isotope measurements traceable to the Vienna Peedee Belemnite (VPDB) with 0.7‰ combined standard uncertainty (or expanded uncertainty of 1.4‰ at 95% confidence level). We perform these measurements on qualified Bruker 400 MHz instruments to certify site-specific carbon isotope delta values in two vanillin materials, VANA-1 and VANB-1, believed to be the first intramolecular isotopic certified reference material (CRMs).

Antibacterial effects of vanilla ingredients provide novel treatment options for infections with multidrug-resistant bacteria - A recent literature review

Due to the increasing application of antibiotics not only in healthcare settings but also in conventional agriculture and farming, multidrug-resistant (MDR) bacterial pathogens are rising worldwide. Given the increasing prevalence of infections caused by MDR bacteria such as Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter species (ESKAPE pathogen complex), it is pivotal to explore novel alternative or adjunct treatment options such as phytochemicals with antibiotic properties. Vanillin and vanillin acid represent biologically active ingredients in vanilla that has been known for long for its health-beneficial including antimicrobial effects besides its role as flavoring agent. Therefore, we performed a literature search from the past 10 years summarizing the knowledge regarding the effects of vanilla constituents against bacterial including MDR pathogens. Our survey revealed that vanillin and vanillic acid exerted potent effects directed against distinct Gram-positive and Gram-negative bacteria by inhibiting growth, viability, biofilm formation, quorum sensing and virulence. Remarkably, when combining vanillin or vanillic acid with defined synthetic antibiotics pronounced synergistic effects directed against distinct pathogenic including ESCAPE strains could be observed. In conclusion, vanilla ingredients constitute promising alternative or adjunct options in the combat of infections caused by MDR bacterial pathogens.

A whiff of the future: functions of phenylalanine-derived aroma compounds and advances in their industrial production

Plants produce myriad aroma compounds-odorous molecules that are key factors in countless aspects of the plant's life cycle, including pollinator attraction and communication within and between plants. For humans, aroma compounds convey accurate information on food type, and are vital for assessing the environment. The phenylpropanoid pathway is the origin of notable aroma compounds, such as raspberry ketone and vanillin. In the last decade, great strides have been made in elucidating this pathway with the identification of numerous aroma-related biosynthetic enzymes and factors regulating metabolic shunts. These scientific achievements, together with public acknowledgment of aroma compounds' medicinal benefits and growing consumer demand for natural products, are driving the development of novel biological sources for wide-scale, eco-friendly, and inexpensive production. Microbes and plants that are readily amenable to metabolic engineering are garnering attention as suitable platforms for achieving this goal. In this review, we discuss the importance of aroma compounds from the perspectives of humans, pollinators and plant-plant interactions. Focusing on vanillin and raspberry ketone, which are of high interest to the industry, we present key knowledge on the biosynthesis and regulation of phenylalanine-derived aroma compounds, describe advances in the adoption of microbes and plants as platforms for their production, and propose routes for improvement.

Comparative Analysis of Bio-Vanillin Recovery from Bioconversion Media Using Pervaporation and Vacuum Distillation

The increasing demand for natural products has led to biotechnological vanillin production, which requires the recovery of vanillin (and vanillyl alcohol at trace concentrations, as in botanical vanillin) from the bioconversion broth, free from potential contaminants: the substrate and metabolites of bioconversion. This work discusses the recovery and fractionation of bio-vanillin, from a bioconversion broth, by pervaporation and by vacuum distillation, coupled with fractionated condensation. The objective was to recover vanillin free of potential contaminants, with maximised fluxes and selectivity for vanillin against water and minimised energy consumption per mass of vanillin recovered. In vacuum distillation fractionated condensation, adding several consecutive water pulses to the feed increased the percentage of recovered vanillin. In pervaporation-fractionated condensation and vacuum distillation-fractionated condensation processes, it was possible to recover vanillin and traces of vanillyl alcohol without the presence of potential contaminants. Vacuum distillation-experiments presented higher vanillin fluxes than pervaporation fractionated condensation experiments, 2.7 ± 0.1 g·m^-2 h^-1 and 1.19 ± 0.01 g·m^-2 h^-1, respectively. However, pervaporation fractionated condensation assures a selectivity of vanillin against water of 4.5 on the pervaporation step (acting as a preconcentration step) and vacuum distillation fractionated condensation requires a higher energy consumption per mass of vanillin recovered when compared with pervaporation- fractionated condensation, 2727 KWh kg_VAN^-1 at 85 °C and 1361 KWh kg_VAN^-1 at 75 °C, respectively.

Engineering a Feruloyl-Coenzyme A Synthase for Bioconversion of Phenylpropanoid Acids into High-Value Aromatic Aldehydes

Aromatic aldehydes find extensive applications in food, perfume, pharmaceutical, and chemical industries. However, a limited natural enzyme selectivity has become the bottleneck of bioconversion of aromatic aldehydes from natural phenylpropanoid acids. Here, based on the original structure of feruloyl-coenzyme A (CoA) synthetase (FCS) from Streptomyces sp. V-1, we engineered five substrate-binding domains to match specific phenylpropanoid acids. FcsCIA^E407A/K483L, FcsMA^{E407R/I481R/K483R}, FcsHA^{E407K/I481K/K483I}, FcsCA^{E407R/I481R/K483T}, and FcsFA^{E407R/I481K/K483R} showed 9.96-, 10.58-, 4.25-, 6.49-, and 8.71-fold enhanced catalytic efficiency for degrading CoA thioesters of cinnamic acid, 4-methoxycinnamic acid, 4-hydroxycinnamic acid, caffeic acid, and ferulic acid, respectively. Molecular dynamics simulation illustrated that novel substrate-binding domains formed strong interaction forces with substrates' methoxy/hydroxyl group and provided hydrophobic/alkaline catalytic surfaces. Five recombinant E. coli with FCS mutants were constructed with the maximum benzaldehyde, p-anisaldehyde, p-hydroxybenzaldehyde, protocatechualdehyde, and vanillin productivity of 6.2 ± 0.3, 5.1 ± 0.23, 4.1 ± 0.25, 7.1 ± 0.3, and 8.7 ± 0.2 mM/h, respectively. Hence, our study provided novel and efficient enzymes for the bioconversion of phenylpropanoid acids into aromatic aldehydes.

From Biomass-Derived p-Hydroxycinnamic Acids to Novel Sustainable and Non-Toxic Phenolics-Based UV-Filters: A Multidisciplinary Journey

Although organic UV-filters are extensively used in cosmetics to protect consumers from the deleterious effects of solar UV radiation-exposure, they suffer from some major drawbacks such as their fossil origin and their toxicity to both humans and the environment. Thus, finding sustainable and non-toxic UV-filters is becoming a topic of great interest for the cosmetic industry. A few years ago, sinapoyl malate was shown to be a powerful naturally occurring UV-filter. Building on these findings, we decided to design and optimize an entire value chain that goes from biomass to innovative biobased and non-toxic lignin-derived UV-filters. This multidisciplinary approach relies on: 1) The production of phenolic synthons using either metabolite extraction from biomass or their bioproduction through synthetic biology/fermentation/in stream product recovery; 2) their functionalization using green chemistry to access sinapoyl malate and analogues; 3) the study of their UV-filtering activity, their photostability, their biological properties; and 4) their photodynamics. This mini-review aims at demonstrating that combining biotechnology, green chemistry, downstream process and photochemistry is a powerful approach to transform biomass and, in particular lignins, into high value-added innovative UV-filters.