Advances in the microbial synthesis of aromatic fragrance molecules / 生物工程学报

Aromatic compounds make up a large part of fragrances and are traditionally produced by chemical synthesis and direct extraction from plants. Chemical synthesis depends on petroleum resources and has disadvantages such as causing environment pollutions and harsh reaction conditions. Due to the low content of aromatic compounds in plants and the low yield of direct extraction, plant extractions require large amounts of plant resources that occupy arable land. In recent years, with the development of metabolic engineering and synthetic biology, microbial synthesis of aromatic compounds from renewable resources has become a promising alternative approach to traditional methods. This review describes the research progress on the synthesis of aromatic fragrances by model microorganisms such as Escherichia coli or yeast, including the synthesis of vanillin through shikimic acid pathway and the synthesis of raspberry ketone through polyketide pathway. Moreover, this review highlights the elucidation of native biosynthesis pathways, the construction of synthetic pathways and metabolic regulation for the production of aromatic fragrances by microbial fermentation.

Tripodalsporormielones A-C, unprecedented cage-like polyketides with complex polyvdent bridged and fused ring systems

A chemical investigation on

A new polyketide from endophytic fungus Aspergillus oryzae derived from Paris polyphylla var. yunnanensis / 中草药

Objective: To study the secondary metabolites of the endophytic fungus Aspergillus oryzae from Paris polyphylla var. yunnanensis in order to find new compounds. Methods: The endophytic fungus A. oryzae was fermented by liquid fermentation. After extraction, silica gel and macroporous adsorption resin were used to separate and purify the extract. The structures of the compounds were identified according to their physical and chemical properties and spectroscopic data. Results: Three compounds were isolated and their structures were identified as 3-amino-4,5-dihydroxy-4,6-dimethyl-2-(2-methylbutanoyl)cyclohex-2-enone (1), 12-N-methyl- cyclo-(L-tryptophyl-L-phenylalanyl) (2) and ditryptophenaline (3). Conclusion: Compound 1 is a new polyketide named asperpolyketide A.

Peptides and polyketides isolated from the marine sponge-derived fungus Aspergillus terreus SCSIO 41008 / 中国天然药物

Two new isomeric modified tripeptides, aspergillamides C and D (compounds 1 and 2), together with fifteen known compounds (compounds 3-17), were obtained from the marine sponge-derived fungus Aspergillus terreus SCSIO 41008. The structures of the new compounds, including absolute configurations, were determined by extensive analyses of spectroscopic data (NMR, MS, UV, and IR) and comparisons between the calculated and experimental electronic circular dichroism (ECD) spectra. Butyrolactone I (compound 11) exhibited strong inhibitory effects against Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB) with the IC being 5.11 ± 0.53 μmol·L, and acted as a noncompetitive inhibitor based on kinetic analysis.

Cloning and expressing of a polyketide synthase gene in Antrodia camphorata / 中草药

Objective To obtained the gene AcPKS1 of Antrodia camphorata, analyze using bioinformatics, and detect the condition of expressing in the different medium. Methods Polyketide synthases gene was obtained from the genome of A. camphorata through analyzing the genome, and the full length of the gene was obtained through designed the special primers including initiation codon and termination codon and the template using cDNA of A. camphorata, which named the gene AcPKS1, and using the bioinformatics analysis and expression profiles analysis in the different medium. Results The full length of AcPKS1 gene was 6 348 bp, including six introns and seven exons, and the expression region encoded 2 115 amino acids; the bioinformatics analysis showed that AcPKS1 was a kind of nonreduced PKS of type in fungi, the domains was SAT-KS-PT-ACP-ACP-TE, and the enzyme catalyzed a new kind of cyclization in the process of polyketides biosynthesis; The expression profiles revealed that glucose was necessary during the expression of AcPKS protein, and the expression quantity of the AcPKS1 protein basically proportion to the content of glucose. Conclusion The result of this text has applied foundation to identify the polyketide synthase gene and take full advantage genomic resources of A. camphorata.

Advances in structure-function relation of plant type Ⅲ polyketide synthases by site-directed mutagenesis / 生物工程学报

Plant type Ⅲ polyketide synthases (PKSs), the pivotal enzymes in the biosynthesis of polyketides, produce backbones of many structurally diverse and functionally different polyketides. So far, a variety of functionally diverse plant type Ⅲ PKSs have been cloned and identified from plant origin. Site-directed mutagenesis is a useful technique to study the complex relationship between protein structure and function. This review summarized advances in the structure-function relation of plant type Ⅲ polyketide synthases by site-directed mutagenesis in recent years, including the modification of the amino acid residues influencing enzyme architectures (such as controlling the specificity of starter substrates, the number of condensation reactions, and the cyclization reactions of the intermediate product). This review provides information to study the structure-function relation of plant type Ⅲ polyketide synthases.

Chinoketides A and B, Two New Antimicrobial Polyketides from the Endophytes of Distylium chinense with the “Black-Box” Co-culture Method

Two new polyketides, chinoketides A and B (1 – 2) with a known compound xylarphthalide A (3), were isolated from the solid medium of the endophytes from the leaves of the relic plant Distylium chinense with the “black-box” co-culture method, and the structures of two new compounds were elucidated by NMR, MS and CD spectra. And the absolute configurations of chinoketides A (1) and B (2) were determined as 2R,3R,8S and 5R,6S by calculating their ECD spectra to compare with the experimental CD spectra. Finally, the antimicrobial activities were evaluated to Erwinia carotovora sub sp. Carotovora (Jones) Bersey et al, and the results showed that compounds 1 – 3 displayed the antimicrobial activities with MIC value at 20.5, 30.4 and 10.2 µg/mL.

Screening of polyketide genes from Brazilian Atlantic Forest soil / Evaluación de genes biosintéticos de policétidos provenientes de suelo de la selva atlántica brasileñae / Avaliação de genes biossintéticos de policetídeos provenientes do solo da Mata Atlântica Brasileira

Abstract Soil is a large source of microorganisms with potential to produce bioactive compounds. Since most of them cannot be cultured, metagenomics has become a useful tool in order to evaluate this potential. The aim of this study was to screen biosynthetic polyketide genes (PKS) present in a metagenomic library constructed from a soil sample isolated from the Brazilian Atlantic Forest. The library comprises 5000 clones with DNA inserts between 40 and 50 Kb. The characterization of the biosynthetic gene clusters of these molecules is a promising alternative to elucidate the biotechnological potential of bioactive compounds in microbial communities. The PKS genes were screened using degenerated primers. The positive clones for PKS systems were isolated, and their nucleotide sequences analysed with bioinformatics tools. The screening yielded two positive clones for PKS II genes. Furthermore, variations in the sequences of the PKS II genes from the metagenomic library were observed when compared with sequences of ketosynthases' databases. With these findings we gain insight into the possible relation between new biosynthetic genes and the production of new secondary metabolites.

Resumen El suelo es una fuente importante de microrganismos con potencial para producir compuestos bioactivos. Dado que la gran mayoría de estos microorganismos no puede cultivarse, la metagenómica se ha convertido en una herramienta útil para evaluar dicho potencial. El objetivo del presente estudio fue evaluar los genes biosintéticos de policétidos (PKS) presentes en una biblioteca metagenómica construida a partir de una muestra de suelo aislada de la selva atlántica brasileña. La biblioteca comprende 5000 clones con insertos de DNA entre 40 y 50 Kb. La caracterización de clústeres de genes biosintéticos de estas moléculas es una alternativa promisoria para elucidar el potencial biotecnológico de los compuestos bioactivos en comunidades microbianas. Los genes biosintéticos de PKS se evaluaron usando cebadores degenerados. Se aislaron los clones positivos para sistemas PKS y sus secuencias de nucleótidos se analizaron con herramientas bioinformáticas. La evaluación arrojó dos clones positivos para genes de PKS II. Además, se observaron variaciones en las secuencias de genes de PKS II de la biblioteca metagenómica cuando se compararon con las secuencias de las bases de datos de cetosintasas. Estos hallazgos proporcionan nueva información sobre la posible relación entre nuevos genes biosintéticos y la producción de nuevos metabolitos secundarios.

Resumo O solo é uma fonte de importante de microrganismos com potencial para produzir compostos bioativos. Considerando que a maioria destes microrganismos não se pode cultivar, a metagenômica tem se convertido em uma ferramenta útil para avaliar este potencial. O objetivo deste estudo foi avaliar os genes biossintéticos de policetídeos (PKS) presentes em uma biblioteca metagenômica construída a partir de uma amostra de solo isolada da Mata Atlântica brasileira. A biblioteca compreende 5000 clones com insertos de DNA entre 40 e 50 Kb. A caracterização de clusters de genes biossintéticos destas moléculas é uma alternativa promissora para elucidar o potencial biotecnológico de compostos bioativos em comunidades microbianas. Os genes PKS foram avaliados usando primers degenerados. Os clones positivos para sistemas PKS foram isolados e suas sequências de nucleotídeos foram analisadas com ferramentas de bioinformática. A avaliação forneceu dois clones positivos para genes PKS II. Além disso, variações nas sequências dos genes PKS II da biblioteca metagenômica foram observadas quando comparadas com sequências da base de dados de cetosintases. Com estas descobertas obtivemos uma visão sobre uma possível relação entre novos genes biossintéticos e a produção de novos metabólitos secundários.

Secondary metabolites from Streptococcus mutans and their ecological roles in dental biofilm / 生物工程学报

Dental biofilms are composed of hundreds of bacterial species, among which Streptococcus mutans is widely recognized as the major pathogen of dental caries. The cariogenic potential of S. mutans is related to its ability to form a robust biofilm on the tooth surface and its acidogenic and acid-tolerant properties. Co-evolution of S. mutans with the host has resulted in the diversity of secondary metabolism of S. mutans in strain level. A variety of secondary metabolites, including 10 bacteriocins (mutacins) and one hybrid Polyketide/Non-Ribosomal Peptide type compound, have been characterized. Studies on these secondary metabolites indicate that they play a significant role either in interspecies or in inter-kingdom interactions in the dental biofilm. As more S. mutans strains are isolated and sequenced, additional secondary metabolites with novel functions will be discovered. The study of secondary metabolites in S. mutans is anticipated to be helpful for oral disease treatment and prevention by providing new strategies.

Antibacterial metabolites from Penicillium sp. I09F 484 / 中国药学杂志

OBJECTIVE: To characterize the antibacterial agents from the culture broth of Penicillium sp. I09F 484. METHODS: The compounds were purified by a combination of chromatographic methods, and their structures were identified by IR, MS, CD, 1D and 2D-NMR spectroscopic data analysis. The antimicrobial activities of the isolates were evaluated by the micro-broth dilution method and the antiviral activities were also assessed. RESULTS: Eight compounds were identified from the cultures of strain I09F 484. Their structures were elucidated as patulin(1), gentisyl alcohol(2), 3-hydroxybenzyl alcohol(3), 2-methylhydroquinone(4), (45, 55)-4, 5-dihydroxy-2-methylcyclohex-2-enone(5), epiepoformin(6), thymidine(7), cyclo(L-Pro-L-Tyr) (8). Compound 1 displayed moderate antibacterial activities with MICs ranging 64-128 μg · mL-1 against a number of pathogenic strains, while 4 was active against Staphylococcus aureus and Staphylococcus epidermidis. Compound 2 displayed antiviral activity against influenza A strains A/FM/1/47 (H1N1) nd A/Hanfang/359/95( H3N2) viruses, with IC50 values of 5.0 and 5.9 μmol · L-1 Respectively. Compound 4 inhibited Coxsackie virus B3 replication, with an IC50 value of 149.4 μmol · L-1. CONCLUSION: Compounds 1-5 are obtained from the strain for the first time. The antibacterial activity of the crude extracts is mainly due to the presence of the known patulin (1). Compounds 2 and 4 show moderate influenza and Coxsackie virus B3 inhibitory activity and the antiviral activities are first assessed.

Two novel polyketides from Peperomia dindygulensis / 中草药

Objective: To study the chemical constituents from Peperomia dindygulensis. Methods: The chemical constituents in chloroform fraction of ethanol extract from P. dindygulensis were isolated and purified by column chromatography over silica gel column, preparative TLC, and semi-preparative HPLC. Their chemical structures were elucidated on the basis of physicochemical and spectral data. Results: Two new polyketides were isolated from the chloroform extracting fraction of P. dindygulensis and identified as (4S)-1,4-dihydroxy-2-(1′, 13′-diketone-octadec-14′E-ene)-1-cyclohexen-3-one (1) and (4S)-1,4-dihydroxy-2-(1′,14′-diketone-octadec-12′E-ene) -1-cyclohexen-3-one (2). Conclusion: Compounds 1 and 2 are new compounds and named as peperomadinone A and peperomadinone B.