Biotransformation of isoeugenol to vanillin by a newly isolated Bacillus pumilus strain: Identification of major metabolites

Strategies for improving the production of bio-based vanillin

Vanillin (4-hydroxy-3-methoxybenzaldehyde) is one of the most popular flavors with wide applications in food, fragrance, and pharmaceutical industries. However, the high cost and limited yield of plant extraction failed to meet the vast market demand of natural vanillin. Vanillin biotechnology has emerged as a sustainable and cost-effective alternative to supply vanillin. In this review, we explored recent advances in vanillin biosynthesis and highlighted the potential of vanillin biotechnology. In particular, we addressed key challenges in using microorganisms and provided promising approaches for improving vanillin production with a special focus on chassis development, pathway construction and process optimization. Future directions of vanillin biosynthesis using inexpensive precursors are also thoroughly discussed.

Production of hydroxytyrosol through whole-cell bioconversion from L-DOPA using engineered Escherichia coli

Hydroxytyrosol (HT), a polyphenolic molecule of high value, is used in the nutraceutical, cosmetic, food, and livestock nutrition industries. As a natural product, HT is chemically manufactured or extracted from olives; nevertheless, the increasing demand mandates the exploration and development of alternative sources, such as heterologous production by recombinant bacteria. In order to achieve this purpose, we have molecularly modified Escherichia coli to carry two plasmids. For conversion of L-DOPA (Levodopa) into HT efficiently, it is necessary to enhance the expression of DODC (DOPA decarboxylase), ADH (alcohol dehydrogenases), MAO (Monoamine oxidase) and GDH (glucose dehydrogenases). The step that significantly affects the rate of ht biosynthesis is likely to be associated with the reaction facilitated by DODC enzymatic activity, as suggested by the result of in vitro catalytic experiment and HPLC. Then Pseudomonas putida, Sus scrofa, Homo sapiens and Levilactobacillus brevis DODC were taken into comparsion. The DODC from H. sapiens is superior to that of P. putida, S. scrofa or L. brevis for HT production. Seven promoters were introduced to increase the expression levels of catalase (CAT) to remove the byproduct H₂O₂ and optimized coexpression strains were obtained after screening. After the 10-hour operation, the optimized whole-cell biocatalyst produced HT at a maximum titer of 4.84 g/L with over 77.5% molar substrate conversion rate.

Synthesis and Biological Activities of Dehydrodiisoeugenol: A Review

Dehydrodiisoeugenol (DHIE) is a neolignan found in more than 17 plant species, including herbs, fruit, and root. DHIE was, for the first time, isolated from Myristica fragrans bark in 1973. Since then, many methodologies have been used for the obtention of DHIE, including classical chemistry synthesis using metal catalysts and biocatalytic synthesis; employing horseradish peroxidase; peroxidase from Cocos nucifera; laccase; culture cells of plants; and microorganisms. Increasing evidence has indicated that DHIE has a wide range of biological activities: anti-inflammatory, anti-oxidant, anti-cancerogenic, and anti-microbial properties. However, evidence in vivo and in human beings is still lacking to support the usefulness potential of DHIE as a therapeutic agent. This study's review was created by searching for relevant DHIE material on websites such as Google Scholar, PubMed, SciFinder, Scholar, Science Direct, and others. This reviews the current state of knowledge regarding the different synthetical routes and biological applications of DHIE.

Biosynthesis of vanillic acid by Ochrobactrum anthropi and its applications

Vanillic acid has always been in high-demand in pharmaceutical, cosmetic, food, flavor, alcohol and polymer industries. Present study achieved highly pure synthesis of vanillic acid from vanillin using whole cells of Ochrobactrum anthropi strain T5_1. The complete biotransformation of vanillin (2 g/L) in to vanillic acid (2.2 g/L) with 95 % yield was achieved in single step in 7 h, whereas 5 g/L vanillin was converted to vanillic acid in 31 h. The vanillic acid thus produced was validated using LC-MS, GC-MS, FTIR and NMR. Further, vanillic acid was evaluated for in vitro anti-tyrosinase and cytotoxic properties on B16F1 skin cell line in dose dependent manner with IC₅₀ values of 15.84 mM and 9.24 mM respectively. The in silico Swiss target study predicted carbonic acid anhydrase IX and XII as key targets of vanillic acid inside the B16F1 skin cell line and revealed the possible mechanism underlying cell toxicity. Molecular docking indicated a strong linkage between vanillic acid and tyrosinase through four hydrogen and several hydrophobic bonds, with ΔG of -3.36 kJ/mol and Ki of 3.46 mM. The bioavailability of vanillic acid was confirmed by the Swiss ADME study with no violation of Lipinski's five rules.

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.

RNase1 can modulate gut microbiota and metabolome after Aeromonas hydrophila infection in blunt snout bream

Pancreatic ribonuclease (RNase1) of Megalobrama amblycephala exhibits both antimicrobial and digestive activity. The gut microbiome improve the digestion and metabolic capacity and enhance the functioning of the immune system of the host against pathogenic bacteria. In this study, we aimed to assess the protective effect of RNase1 on Aeromonas hydrophila-induced inflammation and intestinal microbial metabolism. Megalobrama amblycephala were randomly divided into three groups: control (injected PBS), infection (A. hydrophila-injected), and treatment group (RNase1 pretreatment 24 h before the A. hydrophila injection). The morphological symptoms were significantly alleviated by RNase1. RNase1 reshaped the perturbed gut microbiota by upregulating Proteobacteria and Vibrio richness and downregulating Firmicutes, Chlamydiae, Bacillus, and Gemmobacter richness. The lysophosphatidylcholine, (±) 17 HETE, D- (+) -cellobiose, and PC (20:5) in the treatment group were restored by RNase 1 protein treatment to the level of the control group. In the treatment group, phospholipid metabolism, fatty acid metabolism, glucose metabolism and lipid metabolism were different from the control and infection groups. The proinflammatory factors concentration in intestinal samples significantly increased after A. hydrophila infection. Our results revealed that RNase1 plays an important role in resistance to pathogen invasion, reducing inflammation, and improving intestinal function, thus inhibiting the occurrence of disease.

Efficient Biosynthesis of Vanillin from Isoeugenol by Recombinant Isoeugenol Monooxygenase from Pseudomonas nitroreducens Jin1

Currently, the biotechnological preparation of fragrances using natural materials attracted growing attention. Enzymatic synthesis of vanillin from isoeugenol by recombinant isoeugenol monooxygenase from Pseudomonas nitroreducens Jin1 was systematically investigated herein. With series of work on the construction of recombinant E. coli over-expressing isoeugenol monooxygenase, optimization of the culture conditions for enzyme production and reaction process for converting isoeugenol into vanillin, an increase of 22-fold in the enzyme activity (2050 U/L) was obtained, and the conversion was significantly increased at high substrate concentration with the aid of magnetic chitosan membrane for product isolation in situ. Under optimal conditions, the product concentration and space-time yield reached 252 mM and 115 g/L/d, respectively, and vanillin was obtained in 82.3% yield and > 99% purity in the gram preparative scale. The developed bioprocess showed application potential for efficient preparation of vanillin from inexpensive natural resources.

A rapid and simple ultra high performance liquid chromatography method for the simultaneous determination of methoxyphenol derivatives involved in the eugenol catabolic pathway

An efficient ultra high performance liquid chromatography method of separation was developed for the analysis of six important methoxyphenol derivatives involved in the eugenol catabolic pathway. In the present study, an Acquity UPLC BEH C₁₈ column was used for the chromatographic separation of the industrially important phenolic compounds such as vanillin, vanillic acid, ferulic acid, coniferyl alcohol, and coniferyl aldehyde obtained during microbial transformation of eugenol. Eluted components were identified using the dual wavelength (254 and 310 nm) UV detector. A gradient method of elution using mobile phase of aqueous 1 mM trifluoroacetic acid (Solvent A) and methanol (Solvent B) at a flow rate of 0.3 mL/min separated all the five intermediate methoxyphenol derivatives along with their precursor eugenol within 15 min with stable baseline resolution. Method validation was performed for the accurate quantification of vanillin, coniferyl aldehyde, and eugenol using the parameters of linearity, specificity, precision, limit of detection, limit of quantification, and robustness. The developed method would be helpful for clear separation and identification of the five most important intermediate metabolites of the eugenol catabolism pathway.

Mechanochemical Synthesis of CuO/MgAl2O4 and MgFe2O4 Spinels for Vanillin Production from Isoeugenol and Vanillyl Alcohol

CuO/MgAl₂O₄ and CuO/MgFe₂O₄ catalysts were successfully synthesized with the use of spinel supports by a very simple and low-cost mechanochemical method. High-speed ball-milling was used to synthesize these catalyst supports for the first time. Materials were subsequently characterized by using XRD, FESEM, TEM, EDS-Dot mapping, XPS, BET-BJH, and Magnetic Susceptibility to investigate the physical-chemical characteristics of the catalysts. Acidity evaluation results indicated that the catalyst with the Mg-Al spinel support had more acid sites. XRD results showed a successful synthesis of the catalysts with large crystal sizes. Both catalysts were used in isoeugenol oxidation and vanillyl alcohol to vanillin reactions, with the CuO/MgAl₂O₄ showing optimum results. This catalyst provided 67% conversion (74% selectivity) after 2 h and this value improved to 81% (selectivity 100%) with the second reaction after 8 h. The CuO/MgFe₂O₄ catalyst in the first reaction after five hours revealed 53% conversion (47% selectivity) and after eight hours with the second reaction, the conversion value improved to 64% (100% selectivity). In terms of reusability, CuO/MgAl₂O₄ showed better results than the CuO/MgFe₂O₄ catalyst, for both reactions.

Biotransformation of Isoeugenol into Vanillin Using Immobilized Recombinant Cells Containing Isoeugenol Monooxygenase Active Aggregates

For efficiently enhancing the activity of isoeugenol monooxygenase, a whole cell overproducing active aggregate IEM720-18A was successfully fabricated via the fusion of amphiphilic short peptide 18A (EWLKAFYEKVLEKLKELF) and isoeugenol monooxygenase and then efficiently expressed in E. coli BL21 (DE3). Such resulting bacteria, E. coli BL21 (DE3) harboring pET30a-IEM720-18A was applied in the biotransformation of isoeugenol to vanillin with the optimization of cultivation conditions. Our results revealed that the vanillin concentration reached to the highest level (14.5 mmol/L) under the optimized reaction conditions including 1.5-g cells containing active aggregate of IEM720-18A, 10% (v/v) dimethyl sulfoxide (DMSO), 100 mmol/L isoeugenol, 50 mmol/L glycine-sodium hydroxide buffer (pH 10.5) in 10 mL reaction volume, and 200 rpm at 25 °C for 36 h. Moreover, the active aggregate IEM720-18A was immobilized with 100 mmol/L glutaraldehyde at 4 °C to improve the operational stability. The highest activity could be achieved when the reactions were carried out at 25 °C and the relative activity of the immobilized enzyme maintained over 60% after seven recycles. Our study provides a new approach to the biotransformation of isoeugenol into vanillin.

Vanillin biotechnology: the perspectives and future

The biotechnological production of fragrances is a recent trend that has expanded rapidly in the last two decades. Vanillin is the second most popular flavoring agent after saffron and is extensively used in various applications, e.g., as a food additive in food and beverages and as a masking agent in various pharmaceutical formulations. It is also considered a valuable product for other applications, such as metal plating and the production of other flavoring agents, herbicides, ripening agents, antifoaming agents, and personal and home-use products (such as in deodorants, air fresheners, and floor-polishing agents). In general, three types of vanillin, namely natural, biotechnological, and chemical/synthetic, are available on the market. However, only natural and nature-identical (biotechnologically produced from ferulic acid only) vanillins are considered as food-grade additives by most food-safety control authorities worldwide. In the present review, we summarize recent trends in fermentation technology for vanillin production and discuss the importance of the choice of raw materials for the economically viable production of vanillin. We also describe the key enzymes used in the biotechnological production of vanillin as well as their underlying genes. Research to advance our understanding of the molecular regulation of different pathways involved in vanillin production from ferulic acid is still ongoing. The enhanced knowledge is expected to offer new opportunities for the application of metabolic engineering to optimize the production of nature-identical vanillin. © 2018 Society of Chemical Industry.

Bioconversion of isoeugenol to vanillin and vanillic acid using the resting cells of Trichosporon asahii

40 isoeugenol-tolerant yeasts were isolated from the rhizosphere soil samples which in turn were collected from aromatic plants in different regions of Iran, and further tested for their ability to grow on a minimal medium containing isoeugenol as the sole carbon and energy source. Nine isolates which were able to grow on isoeugenol were examined for their ability to convert isoeugenol into vanillin under growing cell experiments. Of the tested yeasts, the highest conversion efficiency was observed in isolate MP24. The isolate was identified as Trichosporon asahii based on morphological, biochemical and molecular (ITS region) characters and tested to effectively convert isoeugenol into vanillin under resting cell system. A comparative analysis of thin layer chromatography (TLC), UV-Vis spectrometry, and high-performance liquid chromatography (HPLC) verified that vanillin and vanillic acid are accumulated as two major metabolites using T. asahii strain MP24 resting cells. In the presence of 7.5 g/l of wet weight cells of the strain MP24 pre-grown on isoeugenol and harvested at the end of the exponential growth phase, the optimal concentration of vanillin reached 2.4 g/l with a molar conversion of 52.5% in the potassium phosphate buffer (100 mM, pH 5.8) supplemented with 5 g/l of isoeugenol and 2% (v/v) N,N-dimethylformamide (DMF). The total concentration of vanillin and vanillic acid obtained from the bioconversion process was 4.2 g/l (total molar yield of 88.3%). Until now, no data has been published on the conversion of isoeugenol into vanillin by the strains of the genus Trichosporon.

Mechanochemical synthesis of graphene oxide-supported transition metal catalysts for the oxidation of isoeugenol to vanillin

Vanillin is one of the most commonly used natural products, which can also be produced from lignin-derived feedstocks. The chemical synthesis of vanillin is well-established in large-scale production from petrochemical-based starting materials. To overcome this problem, lignin-derived monomers (such as eugenol, isoeugenol, ferulic acid etc.) have been effectively used in the past few years. However, selective and efficient production of vanillin from these feedstocks still remains an issue to replace the existing process. In this work, new transition metal-based catalysts were proposed to investigate their efficiency in vanillin production. Reduced graphene oxide supported Fe and Co catalysts showed high conversion of isoeugenol under mild reaction conditions using H₂O₂ as oxidizing agent. Fe catalysts were more selective as compared to Co catalysts, providing a 63% vanillin selectivity at 61% conversion in 2 h. The mechanochemical process was demonstrated as an effective approach to prepare supported metal catalysts that exhibited high activity for the production of vanillin from isoeugenol.

Transcriptome profiling analysis reveals metabolic changes across various growth phases in Bacillus pumilus BA06

BACKGROUND

Bacillus pumilus can secret abundant extracellular enzymes, and may be used as a potential host for the industrial production of enzymes. It is necessary to understand the metabolic processes during cellular growth. Here, an RNA-seq based transcriptome analysis was applied to examine B. pumilus BA06 across various growth stages to reveal metabolic changes under two conditions.

RESULTS

Based on the gene expression levels, changes to metabolism pathways that were specific to various growth phases were enriched by KEGG analysis. Upon entry into the transition from the exponential growth phase, striking changes were revealed that included down-regulation of the tricarboxylic acid cycle, oxidative phosphorylation, flagellar assembly, and chemotaxis signaling. In contrast, the expression of stress-responding genes was induced when entering the transition phase, suggesting that the cell may suffer from stress during this growth stage. As expected, up-regulation of sporulation-related genes was continuous during the stationary growth phase, which was consistent with the observed sporulation. However, the expression pattern of the various extracellular proteases was different, suggesting that the regulatory mechanism may be distinct for various proteases. In addition, two protein secretion pathways were enriched with genes responsive to the observed protein secretion in B. pumilus. However, the expression of some genes that encode sporulation-related proteins and extracellular proteases was delayed by the addition of gelatin to the minimal medium.

CONCLUSIONS

The transcriptome data depict global alterations in the genome-wide transcriptome across the various growth phases, which will enable an understanding of the physiology and phenotype of B. pumilus through gene expression.

Taxonomic Identity Resolution of Highly Phylogenetically Related Strains and Selection of Phylogenetic Markers by Using Genome-Scale Methods: The Bacillus pumilus Group Case

Bacillus pumilus group strains have been studied due their agronomic, biotechnological or pharmaceutical potential. Classifying strains of this taxonomic group at species level is a challenging procedure since it is composed of seven species that share among them over 99.5% of 16S rRNA gene identity. In this study, first, a whole-genome in silico approach was used to accurately demarcate B. pumilus group strains, as a case of highly phylogenetically related taxa, at the species level. In order to achieve that and consequently to validate or correct taxonomic identities of genomes in public databases, an average nucleotide identity correlation, a core-based phylogenomic and a gene function repertory analyses were performed. Eventually, more than 50% such genomes were found to be misclassified. Hierarchical clustering of gene functional repertoires was also used to infer ecotypes among B. pumilus group species. Furthermore, for the first time the machine-learning algorithm Random Forest was used to rank genes in order of their importance for species classification. We found that ybbP, a gene involved in the synthesis of cyclic di-AMP, was the most important gene for accurately predicting species identity among B. pumilus group strains. Finally, principal component analysis was used to classify strains based on the distances between their ybbP genes. The methodologies described could be utilized more broadly to identify other highly phylogenetically related species in metagenomic or epidemiological assessments.

Biotechnological applications of microbial bioconversions

Modern research has focused on the microbial transformation of a huge variety of organic compounds to obtain compounds of therapeutic and/or industrial interest. Microbial transformation is a useful tool for producing new compounds, as a consequence of the variety of reactions for natural products. This article describes the production of many important compounds by biotransformation. Emphasis is placed on reporting the metabolites that may be of special interest to the pharmaceutical and biotechnological industries, as well as the practical aspects of this work in the field of microbial transformations.

Mimicking a natural pathway for de novo biosynthesis: natural vanillin production from accessible carbon sources

Plant secondary metabolites have been attracting people’s attention for centuries, due to their potentials; however, their production is still difficult and costly. The rich diversity of microbes and microbial genome sequence data provide unprecedented gene resources that enable to develop efficient artificial pathways in microorganisms. Here, by mimicking a natural pathway of plants using microbial genes, a new metabolic route was developed in E. coli for the synthesis of vanillin, the most widely used flavoring agent. A series of factors were systematically investigated for raising production, including efficiency and suitability of genes, gene dosage, and culture media. The metabolically engineered strain produced 97.2 mg/L vanillin from l-tyrosine, 19.3 mg/L from glucose, 13.3 mg/L from xylose and 24.7 mg/L from glycerol. These results show that the metabolic route enables production of natural vanillin from low-cost substrates, suggesting that it is a good strategy to mimick natural pathways for artificial pathway design.

Genomic analysis of a ginger pathogen Bacillus pumilus providing the understanding to the pathogenesis and the novel control strategy

Bacillus pumilus has been widely identified as a pathogen of plant and human, while the genetic information is rarely available for pathogenic B. pumilus strains. B. pumilus GR8 is a pathogen that causes ginger rhizome rot disease by invading ginger rhizome parenchymatous tissues, growing in the extracellular space, and producing plant cell wall-degrading enzymes to destroy ginger cells. In this study, the genome of GR8 was sequenced and characterized. This genome was the third completely sequenced genome of the B. pumilus species, and it exhibited high similarity to the genome of the B. pumilus strain B6033. The genome of GR8 was 3.67 Mb in length and encoded 3,713 putative ORFs. Among these predicted proteins, numerous plant cell wall-degrading enzymes and several proteins associated with invading and adapting to the environment in the extracellular space of the ginger rhizome parenchymatous tissue were found. The GR8 genome contained only one restriction-modification system and no CRISPR/Cas system. The lack of phage-resistant system suggested that phages might be potential agents for the control of GR8. The genomic analysis of GR8 provided the understanding to the pathogenesis and the phage-control strategy of pathogenic B. pumilus strains.

Involvement of Colonizing Bacillus Isolates in Glucovanillin Hydrolysis during the Curing of Vanilla planifolia Andrews

Vanilla beans were analyzed using biochemical methods, which revealed that glucovanillin disperses from the inner part to the outer part of the vanilla bean during the curing process and is simultaneously hydrolyzed by β-d-glucosidase. Enzymatic hydrolysis was found to occur on the surface of the vanilla beans. Transcripts of the β-d-glucosidase gene (bgl) of colonizing microorganisms were detected. The results directly indicate that colonizing microorganisms are involved in glucovanillin hydrolysis. Phylogenetic analysis based on 16S rRNA gene sequences showed that the colonizing microorganisms mainly belonged to the Bacillus genus. bgl was detected in all the isolates and presented clustering similar to that of the isolate taxonomy. Furthermore, inoculation of green fluorescent protein-tagged isolates showed that the Bacillus isolates can colonize vanilla beans. Glucovanillin was metabolized as the sole source of carbon in a culture of the isolates within 24 h. These isolates presented unique glucovanillin degradation capabilities. Vanillin was the major volatile compound in the culture. Other compounds, such as α-cubebene, β-pinene, and guaiacol, were detected in some isolate cultures. Colonizing Bacillus isolates were found to hydrolyze glucovanillin in culture, indirectly demonstrating the involvement of colonizing Bacillus isolates in glucovanillin hydrolysis during the vanilla curing process. Based on these results, we conclude that colonizing Bacillus isolates produce β-d-glucosidase, which mediates glucovanillin hydrolysis and influences flavor formation.

Draft Genome Sequence of Lysinibacillus fusiformis Strain SW-B9, a Novel Strain for Biotransformation of Isoeugenol to Vanillin

Lysinibacillus fusiformis SW-B9 was the first reported strain in L. fusiformis showing effective biotransformation of isoeugenol to vanillin. Here, we report the annotated genome of strain SW-B9, which has special pathways for producing vanillin. The genome will provide a genetic basis for better understanding the physiology of this species.

Genomic and chemical insights into biosurfactant production by the mangrove-derived strain Bacillus safensis CCMA-560

Many Bacillus species can produce biosurfactant, although most of the studies on lipopeptide production by this genus have been focused on Bacillus subtilis. Surfactants are broadly used in pharmaceutical, food and petroleum industry, and biological surfactant shows some advantages over the chemical surfactants, such as less toxicity, production from renewable, cheaper feedstocks and development of novel recombinant hyperproducer strains. This study is aimed to unveil the biosurfactant metabolic pathway and chemical composition in Bacillus safensis strain CCMA-560. The whole genome of the CCMA-560 strain was previously sequenced, and with the aid of bioinformatics tools, its biosurfactant metabolic pathway was compared to other pathways of closely related species. Fourier transform infrared (FTIR) and high-resolution TOF mass spectrometry (MS) were used to characterize the biosurfactant molecule. B. safensis CCMA-560 metabolic pathway is similar to other Bacillus species; however, some differences in amino acid incorporation were observed, and chemical analyses corroborated the genetic results. The strain CCMA-560 harbours two genes flanked by srfAC and srfAD not present in other Bacillus spp., which can be involved in the production of the analogue gramicidin. FTIR and MS showed that B. safensis CCMA-560 produces a mixture of at least four lipopeptides with seven amino acids incorporated and a fatty acid chain with 14 carbons, which makes this molecule similar to the biosurfactant of Bacillus pumilus, namely, pumilacidin. This is the first report on the biosurfactant production by B. safensis, encompassing the investigation of the metabolic pathway and chemical characterization of the biosurfactant molecule.

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

In recent years, biotechnology-derived production of flavors and fragrances has expanded rapidly. The world's most popular flavor, vanillin, is no exception. This review outlines the current state of biotechnology-based vanillin synthesis with the use of ferulic acid, eugenol, and glucose as substrates and bacteria, fungi, and yeasts as microbial production hosts. The de novo biosynthetic pathway of vanillin in the vanilla orchid and the possible applied uses of this new knowledge in the biotechnology-derived and pod-based vanillin industries are also highlighted.

Oxidovanadium(iv) and dioxidovanadium(v) complexes of hydrazones of 2-benzoylpyridine and their catalytic applications

V^V-polymer-supported compounds, their neat analogues and the corresponding peroxido-complexes are prepared and applied as catalyst precursors for the oxidation of isoeugenol.

Biotechnological and molecular approaches for vanillin production: a review

Vanillin is one of the most widely used flavoring agents in the world. As the annual world market demand of vanillin could not be met by natural extraction, chemical synthesis, or tissue culture technology, thus biotechnological approaches may be replacement routes to make production of bio-vanillin economically viable. This review's main focus is to highlight significant aspects of biotechnology with emphasis on the production of vanillin from eugenol, isoeugenol, lignin, ferulic acid, sugars, phenolic stilbenes, vanillic acid, aromatic amino acids, and waste residues by applying fungi, bacteria, and plant cells. Production of biovanillin using GRAS lactic acid bacteria and metabolically engineered microorganisms, genetic organization of vanillin biosynthesis operons/gene cassettes and finally the stability of biovanillin generated through various biotechnological procedures are also critically reviewed in the later sections of the review.

Genome sequence of Bacillus pumilus S-1, an efficient isoeugenol-utilizing producer for natural vanillin

Bacillus pumilus S-1 is an efficient isoeugenol-utilizing producer of natural vanillin. The genome of B. pumilus S-1 contains the epoxide hydrolase and six candidate monooxygenases that make it possible to explore the mechanism involved in conversion of isoenguenol to vanillin in the B. pumilus strain.