ABSTRACT: Impact of Different Starter Cultures on the Microbial Community and Volatile Flavor Compounds in Xuanwei Ham: A Metagenomic and GC-MS Analysis
Project description:Grape volatiles include a great number of compounds, among which monoterpenes, alcohols,esters and carbonyls were found.Grape may be divided into aromatic and non-aromatic varieties. ‘Shine Muscat’ belongs to the aromatic cultivar. The most abundant free compounds detected in Muscat grape were linalool, geraniol, citronellol, nerol. Grapevine (Vitis vinifera L.) is an economically important and widely cultivated fruit crop. Grape quality is important for its market value and is largely decided by its taste and aroma.Gas-chromatograph mass-spectrometry (GC-MS) was performed to observe changes of the volatile compounds.
Project description:Flahaut2013 - Genome-scale metabolic model of L.lactis (MG1363)
Genome-scale metabolic model for Lactococcus lactis
MG1363 and its application to the analysis of flavor formation.
This model is described in the article:
Genome-scale metabolic model for Lactococcus lactis MG1363 and its application to the analysis of flavor formation.
Flahaut NA, Wiersma A, van de Bunt B, Martens DE, Schaap PJ, Sijtsma L, Dos Santos VA, de Vos WM
Applied Microbiology and Biotechnology. 2013; 97(19):8729-8739
Abstract:
Lactococcus lactis subsp. cremoris MG1363 is a paradigm strain for lactococci used in industrial dairy fermentations. However, despite of its importance for process development, no genome-scale metabolic model has been reported thus far. Moreover, current models for other lactococci only focus on growth and sugar degradation. A metabolic model that includes nitrogen metabolism and flavor-forming pathways is instrumental for the understanding and designing new industrial applications of these lactic acid bacteria. A genome-scale, constraint-based model of the metabolism and transport in L. lactis MG1363, accounting for 518 genes, 754 reactions, and 650 metabolites, was developed and experimentally validated. Fifty-nine reactions are directly or indirectly involved in flavor formation. Flux Balance Analysis and Flux Variability Analysis were used to investigate flux distributions within the whole metabolic network. Anaerobic carbon-limited continuous cultures were used for estimating the energetic parameters. A thorough model-driven analysis showing a highly flexible nitrogen metabolism, e.g., branched-chain amino acid catabolism which coupled with the redox balance, is pivotal for the prediction of the formation of different flavor compounds. Furthermore, the model predicted the formation of volatile sulfur compounds as a result of the fermentation. These products were subsequently identified in the experimental fermentations carried out. Thus, the genome-scale metabolic model couples the carbon and nitrogen metabolism in L. lactis MG1363 with complete known catabolic pathways leading to flavor formation. The model provided valuable insights into the metabolic networks underlying flavor formation and has the potential to contribute to new developments in dairy industries and cheese-flavor research.
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Project description:TMT combined with two-dimensional liquid chromatography-tandem mass spectrometry (LC-MS/MS) was utilized for the first time to investigate the changes in protein profiles of Xuanwei ham during different ripening periods (0, 12, 24 and 36 months).
Project description:Transcriptomic and GC-MS metabolomic analysis to provide insight into aroma volatile compounds of ‘Granny Smith’ and ‘Jonagold’ apples (Malus domestica)
Project description:The overall aroma is an important factor of the sensory quality of fruit wines, which attributed to hundreds of volatile compounds. However, the qualitative determination of trace volatile compounds is considered to be very challenging work. GC-Orbitrap-MS with high resolution and high sensitivity provided more possibilities for the determination of volatile compounds, but without the high-resolution mass spectral library. For accuracy of qualitative determination in fruit wines by GC-Orbitrap-MS, a high-resolution mass spectral library, including 22 esters, 11 carbonyl compounds, 10 high alcohols, 7 lactones, 6 acids, 6 furans, 5 pyrazines, 5 terpenes, 4 benzenes, 4 volatile phenols and 1 sulfide, was developed in this study. Not only the HRMS spectrum but also the exact ion fragment, relative abundance, retention indices (RI), CAS number, chemical structure diagram, aroma description and aroma threshold were provided and were shown in a database website (Food Flavor Laboratory, http://foodflavorlab.cn/). HRMS library was used to successfully identify the volatile compounds mentioned above in 16 fruit wines (5 blueberry wines, 6 goji berry wines and 5 hawthorn wines). The library was developed as an important basis for further understanding of trace volatile compounds in fruit wines.
Project description:Coniferous trees use the oleoresin, a mixture of non-volatile non-volatile diterpene acids and a large (20-50%) volatile fraction of mono- and sesquiterpenes, as a defence tool against damaging herbivores and pathogens. Volatilization of monoterpenes increases viscosity of oleoresin and finally leading to polymerization of resin and a formation of protective solid plug. Resin storing conifers form an important source of volatile organic compounds (VOCs) mainly dominated by volatile monoterpenes. In the atmosphere, conifer VOCs react with ozone and OH and nitrous oxide radicals forming secondary organic compounds. This project seeks a better understanding of the genetic control of conifer defences and the role of monoterpenoid compounds under biotic stresses.
Project description:Infiltrating T-lymphocytes from the peripheral blood into the central nervous system (CNS) play a dynamic role in the development of a neurological immune-mediated diseases. HAM/TSP is a chronic progressive inflammatory neurological disorder associated with human T-cell lymphotropic virus type I (HTLV-I) infection. In this chronic myelopathy, virus-infected circulating T-cells infiltrate the CNS and an immune response is initiated against the components of CNS. As the HTLV-I proviral load (PVL) has been used as the best clinical marker for patient diagnostic with HAM/TSP, we hypothesized there might be a signature on T-cell receptor (TCR) clonal repertoire in these patients, which could distinguish HAM/TSP patients from the healthy population, as well as from patients with a more heterogeneous CNS-reactive inflammatory disease as multiple sclerosis (MS). With this in mind, we applied an innovative unbiased molecular technique – unique molecular identifier (UMI) library-strategy to investigate with high accuracy the TCR clonal repertoire by high throughput sequencing (HTS) technology. cDNA-TCR β-chain libraries were sequenced from 2 million peripheral mononuclear cells (PBMCs) in 14 HAM/TSP patients, 34 MS patients and 20 healthy controls (HC). To address whether the clonal expansion correlates with the patient’s PVL level, analysis of longitudinal TCR repertoire was performed in 2 HAM/TSP patients. Over 5.6 million TCR sequences were generated per sample on HiSeq 2500 Illumina system and analyzed through the molecular identifier groups-based error correction pipeline (MiGEC). Bioinformatic analysis showed that clones with more than 8 reads had a lower coefficient of variation (CV) and then could be used with confidence to evaluate the TCR clonal expansion. While HAM/TSP patients showed the higher clonal T-cell expansion compared to MS and HC, increase of the TCR clonal expansion was inversely correlated with the diversity of TCR repertoire in all subject’s group. In addition, correlation of the PVL with TCR clonal expansion was observed in HAM/TSP patients at longitudinal time-points. Surprisingly, MS patients showed a higher diversity of TCR repertoire along with a very slight clonal T-cell expansion in comparison to either HAM/TSP patients or HC. Despite of the higher TCR clonal expansion in HAM/TSP patients, a non-shared or “private” TCR repertoire was observed in these patients. No clones that shared the same CDR3 amino acid sequences were seen in HC and MS patients. However, a cluster of related CDR3 amino acid sequences were observed for 18 out of 34 MS patients when evaluated by phylogenetic tree analysis. It suggestes that a TCR-repertoire signature might characterize patients with MS. Our findings suggest that even though a unique TCR-b repertoire shapes the immune response in patients with neurological immune-mediated disease, a relatedness on clonal T-cell repertoire exist in MS.
Project description:Interventions: Gold Standard:pathological diagnosis ;Index test:Volatile organic compounds detected by gas chromatography-mass spectrometer and gas chromatography-ion migration spectrometry
Primary outcome(s): Volatile organic compounds;sensitivity;specificity
Study Design: Diagnostic test for accuracy
Project description:Transciptomic changes in tobacco (Nicotiana tabacum cv. Samsun) following exposure to microbial volatile organic compounds (MVOCs) emitted by Cladosporium sphaerospermum isolate TC09 (NRRL 67603) were investigated. Germinated seedling plants were cultured in Magenta GA7 vessels containing Murashige and Skoog (MS) medium supplemented with 30 g/L sucrose with and without fungal cultures that were included in the vessel but placed in a separated container. Ten days after the onset of MVOC exposure, tissue samples including the apical meristem and terminal leaves were collected and subject to RNA sequencing and transcriptome analysis using available tomato genome as reference. Our study revealed massive number of differentially expressed genes (DEGs) associated with diverse biological processes including cell expansion and cell cycle, photosynthesis, phytohormone homeostasis and defense responses as a consequence of short-term exposure to potent MVOCs.