CRISPR/Cas9-based genome editing of 14 lipid metabolic genes reveals a sporopollenin metabolon ZmPKSB-ZmTKPR1-1/-2 required for pollen exine formation in maize.

Lipid biosynthesis and transport are essential for plant male reproduction. Compared with Arabidopsis and rice, relatively fewer maize lipid metabolic genic male-sterility (GMS) genes have been identified, and the sporopollenin metabolon in maize anther remains unknown. Here, we identified two maize GMS genes, ZmTKPR1-1 and ZmTKPR1-2, by CRISPR/Cas9 mutagenesis of 14 lipid metabolic genes with anther stage-specific expression patterns. Among them, tkpr1-1/-2 double mutants displayed complete male sterility with delayed tapetum degradation and abortive pollen. ZmTKPR1-1 and ZmTKPR1-2 encode tetraketide α-pyrone reductases and have catalytic activities in reducing tetraketide α-pyrone produced by ZmPKSB (polyketide synthase B). Several conserved catalytic sites (S128/130, Y164/166 and K168/170 in ZmTKPR1-1/-2) are essential for their enzymatic activities. Both ZmTKPR1-1 and ZmTKPR1-2 are directly activated by ZmMYB84, and their encoded proteins are localized in both the endoplasmic reticulum and nuclei. Based on protein structure prediction, molecular docking, site-directed mutagenesis and biochemical assays, the sporopollenin biosynthetic metabolon ZmPKSB-ZmTKPR1-1/-2 was identified to control pollen exine formation in maize anther. Although ZmTKPR1-1/-2 and ZmPKSB formed a protein complex, their mutants showed different, even opposite, defective phenotypes of anther cuticle and pollen exine. Our findings discover new maize GMS genes that can contribute to male-sterility line-assisted maize breeding and also provide new insights into the metabolon-regulated sporopollenin biosynthesis in maize anther.

OsTKPR1 proteins with a single amino acid substitution fail the synthesis of a specific sporopollenin precursor and cause abnormal exine and pollen development in rice.

Fatty acid derivatives are key components of rice pollen exine. The synthesis of aliphatic sporopollenin precursors are initiated in the plastids of the tapetal cells, followed by multiple-step reactions conducted in the endoplasmic reticulum (ER). However, the relative contribution of different precursors to the precise structure of sporopollenin remains largely elusive, let alone the underlying mechanism. Here, we report that two complete male sterile mutants ostkpr1-3 (Tetraketide α-pyrone reductase 1-3, with OsTKPR1P124S substitution) and ostkpr1-4 (with truncated OsTKPR1stop) are defective in pollen exine, Ubisch body and anther cuticle development where ostkpr1-4 display severer phenotypes. Remarkably, OsTKPR1 could produce reduced hydroxylated tetraketide α-pyrone and reduced tetraketide α-pyrone, whereas OsTKPR1P124S fails to produce the latter. Pairwise interaction assays show that mutated OsTKPR1P124S is able to integrate into a recently characterized metabolon, thus its altered catalytic activity is not due to dis-integrity of the metabolon. In short, we find that reduced tetraketide α-pyrone is a key sporopollenin precursor required for normal exine formation, and the conserved 124th proline of OsTKPR1 is essential for the reduction activity. Therefore, this study provided new insights into the sporopollenin precursor constitution critical for exine formation.

Development of the production of 2-pyrone-4,6-dicarboxylic acid from lignin extracts, which are industrially formed as by-products, as raw materials.

Lignosulfonate is a by-product of the cooking process by sulfite pulping for paper manufacturing. The treatment of wood chips by various salts of sulfurous acid solubilizes lignin to produce a cellulose-rich wood pulp. Developing a technique for the conversion of lignosulfonate by-product to high value materials has an important industrial utility. Sphingobium sp. strain SYK-6, which was isolated from pulping wastewater, is one of the best enzymatically or genetically characterized bacteria for degrading lignin-derived aromatics. We have previously established a system for the production of 2-pyrone-4,6-dicarboxylic acid (PDC), a novel platform chemical that can produce a variety of bio-based polymers, by introducing of ligA, ligB, and ligC genes from SYK-6 into a mutant strain of Pseudomonas putida PpY1100. In this study, extracts from lignosulfonates, which were desulphonated and depolymerized by alkaline oxidation, were evaluated as substrates for microbiological conversion to PDC by the transgenic bacteria.

Producing Biochemicals in Yarrowia lipolytica from Xylose through a Strain Mating Approach.

Enabling xylose catabolism is challenging, especially for unconventional yeasts and previously engineered background strains. In this study, the efficacy of a yeast mating approach with Yarrowia lipolytica that can combine a previously engineering and evolved xylose phenotype with a metabolite overproduction phenotype is demonstrated. Specifically, several engineered Y. lipolytica strains that produce α-linolenic acid (ALA), riboflavin, and triacetic acid lactone (TAL) with an engineered and adapted xylose-utilizing strain to obtain three diploid strains that rapidly produce these molecules directly from xylose are mated. Titers of 0.52 g L-1 ALA, 96.6 mg L-1 riboflavin, and 2.9 g L-1 TAL, are obtained from xylose in flask cultures and 1.42 g L-1 production of ALA is obtained using bioreactor condition. This total production level is generally on par or higher than the parental strain cultivated on glucose, although specific productivities decreased as a result of improved overall cell growth by the diploid strains. In the case of ALA, this lipid content reached similar levels to that of flaxseed oil. This result showcases the first study using strain mating in Y. lipolytica for producing biomolecules from xylose, and thus demonstrates the utility of this approach as a routine tool for metabolic engineering.

The integration of metabolome and proteome reveals bioactive polyphenols and hispidin in ARTP mutagenized Phellinus baumii.

Phellinus baumii, also called "Sang Huang" in China, is broadly used as a kind of health food or folk medicine in Asia for its high biological activities, e.g. anti-tumor, anti-oxidation and anti-inflammatory activities. Although some previous studies have indicated that polysaccharides and flavonoids showed the activity of inhibiting tumor cells, the active metabolites of P. baumii needs further research. In our study, a stable P. baumii mutant (A67), generated by ARTP mutagenesis strategy, showed more significantly inhibiting tumor cells and enhancing antioxidant activity. Our further studies found that the increase of polyphenols content, especially hispidin, was an important reason of the biological activity enhancement of A67. According to the results of the integrated metabolome and proteome study, the increase of polyphenol content was caused by upregulation of the phenylpropanoid biosynthesis. This study expanded the understanding of active compounds and metabolic pathway of P. baumii.

Single Production of Kojic Acid by Aspergillus flavus and the Revision of Flufuran.

Timor Island is very hot and dry due to the high intensity of sunlight experienced throughout the year. The endophytic fungi Aspergillus flavus had been isolated from medicinal plants such as Catharanthus roseus, Annona squamosa and Curcuma xanthorisa. The endophytic fungi A. flavus from each plant was cultivated on solid rice media and then analyzed for its capability for producing kojic acid. The production of kojic acid was analyzed by HPLC; the highest amount of kojic acid was observed from the endophytic fungi A. flavus, isolated from the stem of Catharanthus roseus, followed by A. flavus from Annona squamosa and Curcuma xanthorisa. Simple VLC fractionation of the extract of A. flavus from C.roseus led to the isolation of around 11.1 g of pure kojic acid. The structure of kojic acid (1) was confirmed by NMR and MS spectroscopic data. A comparison of the NMR data with the literature supported the revision of the natural product flufuran to kojic acid. To the best of our knowledge, this is the first report of a strain of endophytic fungi producing only kojic acid without any other toxic metabolites such as alfatoxins. Therefore, this Aspergillus flavus strain can be applied as a potential producer of kojic acid for industrial use.

Identification and characterization of type III polyketide synthase genes from culturable endophytes of ethnomedicinal plants.

Endophytic fungi provide benefits to host plants by producing a diverse class of secondary metabolites (natural products). Arrays of polyketide natural products are synthesized by specific classes of polyketide synthases (PKS I, II and III) in host organisms. In the present study, we attempt to screen and identify type III PKSs in culturable fungal endophytes isolated from the ethno medicinal plants including Arbus precatorius, Bacopa monnieri,Citrus aurantifolia and Datura metel to detect the genetic potential of endophytic fungi in producing bioactive compounds. A total of seventeen endophytic fungal strains belonging to eight genera were identified using fungal morphology and rDNA-ITS phylogenetic analyses. A CODEHOP-PCR based strategy was followed to design degenerate primers for the screening of type III PKS genes from fungal endophytes. We had successfully amplified partial PKS genes from eight endophytes. The amplified PKS sequences showed 60-99% identity to already characterized/putative PKS genes. From the partial sequence of FiPKS from Fusarium incarnatum BMER1, a full-length gene was amplified, cloned and characterized. FiPKScDNA was cloned and expressed in E. coli Lemo21 (DE3) and the purified protein was shown to produce pyrones and resorcinols using acyl-CoA thioesters as substrates. FiPKS showed the highest catalytic efficiency of 7.6 × 104 s-1 M-1 with stearoyl CoA as a starter unit. This study reports the identification and characterization of type III PKS from endophytes of medicinal plants by CODEHOP PCR.

Enzymes and Pathways of Kavain Bioactivation and Biotransformation.

Kavain is an active and major component in Piper methysticum Forst. (kava), which is a widely used dietary supplement for the treatment of anxiety, insomnia, and stress. However, kava-containing products can cause liver toxicity, and its underlying mechanisms are understudied. Cytochrome P450s (CYPs)-mediated bioactivation and biotransformation are highly associated with drug toxicity. In the current study, we profiled the metabolic pathways of kavain in mouse liver, urine, and feces. Overall, 28 kavain metabolites were identified including 17 new ones. The metabolic pathways of kavain include glutathione (GSH) conjugation, oxidation, dehydrogenation, O-demethylation, sulfation, and glucuronidation. The identification of kavain-GSH adducts suggests the formation of reactive metabolites of kavain in the liver. We further illustrated that CYP2C19, a highly polymorphic and inducible enzyme, was the major enzyme contributing to kavain biotransformation and bioactivation. Our data can be used to guide the safe use of kava products by preventing potential herb-drug interactions and hepatotoxicity.

An In-Vitro Assay Estimating Changes in Melanin Content of Melanoma Cells due to Ultra-Dilute, Potentized Preparations.

INTRODUCTION: The authors had previously conducted an in-vitro study to observe the effect of homeopathic medicines on melanogenesis, demonstrating anti-vitiligo potential by increasing the melanin content in murine B16F10 melanoma cells. A similar experiment was performed using further homeopathic preparations sourced from kojic acid (KA), hydrogen peroxide (H2O2; HP), 6-biopterin (BP), and [Nle4, D-Phe7]-α-melanocyte-stimulating hormone (NLE), some of which are known to induce vitiligo or melano-destruction at physiological dose. MATERIALS AND METHODS: The homeopathic preparations of BP, KA, NLE, and HP were used in 30c potency. Alcohol and potentized alcohol were used as vehicle controls. Prior to starting the main experiment, the viability of B16F10 melanoma cells after treatment with study preparations was assayed. Melanin content (at 48 h and 96 h) and tyrosinase activity in melanocytes were determined. RESULTS: At the end of 48 hours, NLE and HP in 30c potency had a significantly greater melanin content (p = 0.015 and p = 0.039, respectively) compared with controls; BP and KA in 30c potency had no significant effects. No significant changes were seen at the end of 96 hours. KA, NLE, HP, and vehicle controls showed an inhibition of tyrosinase activity. CONCLUSION: The study demonstrated melanogenic effects of two homeopathic preparations. Further research to evaluate the therapeutic efficacy of these medicines is warranted.

Neuroprotective Secondary Metabolite Produced by an Endophytic Fungus, Neosartorya fischeri JS0553, Isolated from Glehnia littoralis.

Roots of Glehnia littoralis have been used to heal stroke as a traditional medicine. Even though many studies on this plant have been conducted, the secondary metabolites produced by its endophytes and their bioactivities have not been investigated thus far. Therefore, a new meroditerpenoid named sartorypyrone E (1) and eight known compounds (2-9) were isolated from extracts of cultured Neosartorya fischeri JS0553, an endophyte of G. littoralis. The isolated metabolites were identified using spectroscopic methods and chemical reaction, based on a comparison to literature data. Relative and absolute stereochemistries of compound 1 were also elucidated. To identify the protective effects of isolated compounds (1-9) in HT22 cells against glutamate-induced cytotoxicity, we assessed inhibition of cell death, intracellular reactive oxygen species (ROS) accumulation, and calcium ion (Ca2+) influx. Among the isolates, compound 8, identified as fischerin, showed significant neuroprotective activity on glutamate-mediated HT22 cell death through inhibition of ROS, Ca2+ influx, and phosphorylation of mitogen-activated protein kinase, including c-Jun N-terminal kinase, extracellular signal-regulated kinase, and p38. The results suggested that the metabolites produced by the endophyte N. fischeri JS0553 might be related to the neuroprotective activity of its host plant, G. littoralis.

α-Pyrones, secondary metabolites from fungus Cephalotrichum microsporum and their bioactivities.

Cephalotrichum microsporum (SYP-F 7763) was a fungus isolated from the rhizosphere soil of traditional Chinese medicine Panax notoginseng. The EtOAc extract of Cephalotrichum microsporum cultivated on sterilized moistened-rice medium was separated by various chromatographic techniques, which yielded 11 metabolites (1-11) of this fungus. On the basis of the widely spectroscopic data, the chemical structures of isolated metabolites were determined, most of which were α-pyrones, including 5 compounds (4-7, and 10) unreported. In the anti-bacterial bioassay, compound 1 displayed significant inhibitory effects on three pathogenic bacteria, MR S. aureus, S. aureus, and B. cereus. α-Pyrones 2, 3, and 5-7 also displayed moderate inhibitory effects on MR S. aureus, S. aureus, and B. subtilis, which could be the major anti-bacterial constituents of Cephalotrichum microsporum. Additionally, compounds 1, 4, and 5 displayed significant cytotoxicity on five human cancer cell lines, with the IC50 values < 20 µM, which are more effective than positive control 5-fluorouracil. Therefore, α-pyrones were important secondary metabolites of Cephalotrichum microsporum, which displayed anti-bacterial and anti-tumor activities.

Quantification and Discrimination of in Vitro Regeneration Swertia nervosa at Different Growth Periods using the UPLC/UV Coupled with Chemometric Method.

BACKGROUND: Swertia nervosa (Wall. ex G. Don) C. B. Clarke, a promising traditional herbal medicine for the treatment of liver disorders, is endangered due to its extensive collection and unsustainable harvesting practices. OBJECTIVE: The aim of this study is to discuss the diversity of metabolites (loganic acid, sweroside, swertiamarin, and gentiopicroside) at different growth stages and organs of Swertia nervosa using the ultra-high-performance LC (UPLC)/UV coupled with chemometric method. METHODS: UPLC data, UV data, and data fusion were treated separately to find more useful information by partial least-squares discriminant analysis (PLS-DA). Hierarchical cluster analysis (HCA), an unsupervised method, was then employed for validating the results from PLS-DA. RESULTS: Three strategies displayed different chemical information associated with the sample discrimination. UV information mainly contributed to the classification of different organs; UPLC information was prominently responsible for both organs and growth periods; the data fusion did not perform with apparent superiority compared with single data analysis, although it provided useful information to differentiate leaves that could not be recognized by UPLC. The quantification result showed that the content of swertiamarin was the highest compared with the other three metabolites, especially in leaves at the rooted stage (19.57 ± 5.34 mg/g). Therefore, we speculated that interactive transformations occurred among these four metabolites, facilitated by root formation. CONCLUSIONS: This work will contribute to exploitation of bioactive compounds of S. nervosa, as well as its large-scale propagation. HIGHLIGHTS: The roots formation may influence the distribution and accumulation of metabolites.

Cloning and Characterization of Two Iridoid Synthase Homologs from Swertia Mussotii.

Swertia mussotii is an important medicinal plant found on the Qinghai Tibetan Plateau that has great economic and medicinal value. This plant has enjoyed a long history of use as a curative for hepatitis. The biological activity of secoiridoids, including gentiopicroside and swertiamarin, has been mainly tested for its anti-hepatitis effects. Here, we identify two candidate genes (SmIS1 and SmIS2) that are homologues of iridoid synthase and that are components of the secoiridoid pathway in S. mussotii. Using sequencing and phylogenetic analyses, we confirm that SmIS1 and SmIS2 contain six conserved short-chain dehydrogenases/reductase (SDR) motifs and thus belong to the P5ßRs group. The two purified Escherichia coli-expressed proteins reduced 8-oxogeranial to both nepetalactol and iridodials. A comparison of the kinetic parameters of SmIS1 and SmIS2 recombinant proteins revealed that SmIS2 has a lower affinity than SmIS1 for 8-oxogeranial. Transcript levels of the two genes were analysed in three different tissues of S. mussotii using semi-quantitative RT-PCR and RT-qPCR. SmIS1 and SmIS2 expression levels were more abundant in leaves and stems. This investigation adds to our knowledge of P5ßRs genes in the secoiridoid synthesis pathway and provides candidate genes for genetically improving S. mussotii by enhancing secondary metabolite production.

Antioxidant and Genotoxic Properties of Hispidin Isolated from the Velvet-Top Mushroom, Phaeolus schweinitzii (Agaricomycetes).

Antioxidant and genotoxic properties of hispidin isolated from the Phaeolus schweinitzii mushroom were evaluated with various assays. Hispidin demonstrated strong free radical scavenging, oxygen radical absorbance capacity, and ferric-reducing antioxidant power; in all applied assays, hispidin exhibited antioxidant capacity similar to or higher than that of the reference antioxidant Trolox. Genotoxic activity of hispidin was assessed using different end points: chromosome aberrations, micronuclei, sister chromatid exchanges, and primary DNA damage (detected by the comet assay) in human lymphocytes in vitro, and gene mutations in the Salmonella/microsome test. Hispidin did not increase the frequency of chromosome aberrations, micronuclei, or primary DNA damage in human lymphocytes in vitro and did not produce reverse mutation in bacterial cells. However, we identified in human lymphocytes a statistically significant dose-dependent increase in sister chromatid exchange frequency and a decrease in replication index and nuclear division index values.

Secondary metabolites from Aspergillus japonicus CAM231, an endophytic fungus associated with Garcinia preussii.

Chemical investigation of Aspergillus japonicus CAM231, isolated from the leaf of Garcina preussii collected in Cameroon, yielded two new compounds; one pyrone derivative, hydroxy neovasinin (1) and one phenol derivative, asperolan (2), together with two known compounds neovasifurarone B (3) and variecolin (4). The structures of the two new compounds were established using intensive NMR spectroscopy and HRMS spectra in comparison with data found in literature. The structure of compound 1 was confirmed by single-crystal X-ray crystallographic analysis in combination with NOESY experiment. The new compounds were screened for their cytotoxic and antibacterial properties; however, the tested compounds displayed no significant activities.

Functional characterization and expression of GASCL1 and GASCL2, two anther-specific chalcone synthase like enzymes from Gerbera hybrida.

The chalcone synthase superfamily consists of type III polyketidesynthases (PKSs), enzymes responsible for producing plant secondary metabolites with various biological and pharmacological activities. Anther-specific chalcone synthase-like enzymes (ASCLs) represent an ancient group of type III PKSs involved in the biosynthesis of sporopollenin, the main component of the exine layer of moss spores and mature pollen grains of seed plants. In the latter, ASCL proteins are localized in the tapetal cells of the anther where they participate in sporopollenin biosynthesis and exine formation within the locule. It is thought that the enzymes responsible for sporopollenin biosynthesis are highly conserved, and thus far, each angiosperm species with a genome sequenced has possessed two ASCL genes, which in Arabidopsis thaliana are PKSA and PKSB. The Gerbera hybrida (gerbera) PKS protein family consists of three chalcone synthases (GCHS1, GCHS3 and GCHS4) and three 2-pyrone synthases (G2PS1, G2PS2 and G2PS3). In previous studies we have demonstrated the functions of chalcone synthases in flavonoid biosynthesis, and the involvement of 2-pyrone synthases in the biosynthesis of antimicrobial compounds found in gerbera. In this study we expanded the gerbera PKS-family by functionally characterizing two gerbera ASCL proteins. In vitro enzymatic studies using purified recombinant proteins showed that both GASCL1 and GASCL2 were able to use medium and long-chain acyl-CoA starters and perform two to three condensation reactions of malonyl-CoA to produce tri- and tetraketide 2-pyrones, usually referred to as alpha-pyrones in sporopollenin literature. Both GASCL1 and GASCL2 genes were expressed only in floral organs, with most expression observed in anthers. In the anthers, transcripts of both genes showed strict tapetum-specific localization.

High-throughput sequencing and de novo transcriptome assembly of Swertia japonica to identify genes involved in the biosynthesis of therapeutic metabolites.

KEY MESSAGE: Here, we report potential transcripts involved in the biosynthesis of therapeutic metabolites in Swertia japonica , the first report of transcriptome assembly, and characterization of the medicinal plant from Swertia genus. Swertia genus, representing over 170 plant species including herbs such as S. chirata, S. hookeri, S. longifolia, S. japonica, among others, have been used as the traditional medicine in China, India, Korea, and Japan for thousands of years. Due to the lack of genomic and transcriptomic resources, little is known about the molecular basis involved in the biosynthesis of characteristic key bioactive metabolites. Here, we performed deep-transcriptome sequencing for the aerial tissues and the roots of S. japonica, generating over 2 billion raw reads with an average length of 101 bps. Using a combined approach of three popular assemblers, de novo transcriptome assembly for S. japonica was obtained, yielding 81,729 unigenes having an average length of 884 bps and N50 value of 1452 bps, of which 46,963 unigenes were annotated based on the sequence similarity against NCBI-nr protein database. Annotation of transcriptome assembly resulted in the identification of putative genes encoding all enzymes from the key therapeutic metabolite biosynthesis pathways. Transcript abundance analysis, gene ontology enrichment analysis, and KEGG pathway enrichment analysis revealed metabolic processes being up-regulated in the aerial tissues with respect to the roots of S. japonica. We also identified 37 unigenes as potential candidates involved in the glycosylation of bioactive metabolites. Being the first report of transcriptome assembly and annotation for any of the Swertia species, this study will be a valuable resource for future investigations on the biosynthetic pathways of therapeutic metabolites and their regulations.

Mode of Action of the Sesquiterpene Lactones Psilostachyin and Psilostachyin C on Trypanosoma cruzi.

Trypanosoma cruzi is the causative agent of Chagas' disease, which is a major endemic disease in Latin America and is recognized by the WHO as one of the 17 neglected tropical diseases in the world. Psilostachyin and psilostachyin C, two sesquiterpene lactones isolated from Ambrosia spp., have been demonstrated to have trypanocidal activity. Considering both the potential therapeutic targets present in the parasite, and the several mechanisms of action proposed for sesquiterpene lactones, the aim of this work was to characterize the mode of action of psilostachyin and psilostachyin C on Trypanosoma cruzi and to identify the possible targets for these molecules. Psilostachyin and psilostachyin C were isolated from Ambrosia tenuifolia and Ambrosia scabra, respectively. Interaction of sesquiterpene lactones with hemin, the induction of oxidative stress, the inhibition of cruzipain and trypanothione reductase and their ability to inhibit sterol biosynthesis were evaluated. The induction of cell death by apoptosis was also evaluated by analyzing phosphatidylserine exposure detected using annexin-V/propidium iodide, decreased mitochondrial membrane potential, assessed with Rhodamine 123 and nuclear DNA fragmentation evaluated by the TUNEL assay. Both STLs were capable of interacting with hemin. Psilostachyin increased about 5 times the generation of reactive oxygen species in Trypanosoma cruzi after a 4h treatment, unlike psilostachyin C which induced an increase in reactive oxygen species levels of only 1.5 times. Only psilostachyin C was able to inhibit the biosynthesis of ergosterol, causing an accumulation of squalene. Both sesquiterpene lactones induced parasite death by apoptosis. Upon evaluating the combination of both compounds, and additive trypanocidal effect was observed. Despite their structural similarity, both sesquiterpene lactones exerted their anti-T. cruzi activity through interaction with different targets. Psilostachyin accomplished its antiparasitic effect by interacting with hemin, while psilostachyin C interfered with sterol synthesis.

Production of δ-decalactone from linoleic acid via 13-hydroxy-9(Z)-octadecenoic acid intermediate by one-pot reaction using linoleate 13-hydratase and whole Yarrowia lipolytica cells.

OBJECTIVE: To produce δ-decalactone from linoleic acid by one-pot reaction using linoleate 13-hydratase with supplementation with whole Yarrowia lipolytica cells. RESULTS: Whole Y. lipolytica cells at 25 g l(-1) produced1.9 g l(-1) δ-decalactone from 7.5 g 13-hydroxy-9(Z)-octadecenoic acid l(-1) at pH 7.5 and 30 °C for 21 h. Linoleate 13-hydratase from Lactobacillus acidophilus at 3.5 g l(-1) with supplementation with 25 g Y. lipolytica cells l(-1) in one pot at 3 h produced 1.9 g l(-1) δ-decalactone from 10 g linoleic acid l(-1) via 13-hydroxy-9(Z)-octadecenoic acid intermediate at pH 7.5 and 30°C after 18 h, with a molar conversion yield of 31 % and productivity of 106 mg l(-1) h(-1). CONCLUSION: To the best of our knowledge, this is the first production of δ-decalactone using unsaturated fatty acid.

Biotransformation of swertiamarin by Aspergillus niger.

The biotransforamtion of swertiamarin has been carried out using Aspergillus niger. The results showed that 60% swertiamarin were metabolized into two metabolites during the 5 days of biotransformation. The metabolites were identified as erythrocentaurin and 5-ethylidene-8-hydroxy-3,4,5,6,7,8-hexahydro-1Hpyrano[3,4-c]-pyridine-1-one, a novel alkaloid, with NMR and MS. The hydrolysis of glucosidic bond catalyzed by ß-D-glucosidase was found to be the rate-limiting reaction in pathway of biotransformation of swertiamarin.