Investigating the physiology of cyanobacteria cultured under a diel light regime is relevant for a better understanding of the resulting growth characteristics and for specific biotechnological applications that are foreseen for these photosynthetic organisms. Here, we present the results of a multiomics study of the model cyanobacterium Synechocystis sp. strain PCC 6803, cultured in a lab-scale photobioreactor in physiological conditions relevant for large-scale culturing. The culture was sparged with N 2 and CO 2 , leading to an anoxic environment during the dark period. Growth followed the availability of light. Metabolite analysis performed with 1 H nuclear magnetic resonance analysis showed that amino acids involved in nitrogen and sulfur assimilation showed elevated levels in the light. Most protein levels, analyzed through mass spectrometry, remained rather stable. However, several high-light-response proteins and stress-response proteins showed distinct changes at the onset of the light period. Microarray-based transcript analysis found common patterns of ϳ56% of the transcriptome following the diel regime. These oscillating transcripts could be grouped coarsely into genes that were upregulated and downregulated in the dark period. The accumulated glycogen was degraded in the anaerobic environment in the dark. A small part was degraded gradually, reflecting basic maintenance requirements of the cells in darkness. Surprisingly, the largest part was degraded rapidly in a short time span at the end of the dark period. This degradation could allow rapid formation of metabolic intermediates at the end of the dark period, preparing the cells for the resumption of growth at the start of the light period. IMPORTANCEIndustrial-scale biotechnological applications are anticipated for cyanobacteria. We simulated large-scale high-cell-density culturing of Synechocystis sp. PCC 6803 under a diel light regime in a lab-scale photobioreactor. In BG-11 medium, Synechocystis grew only in the light. Metabolite analysis grouped the collected samples according to the light and dark conditions. Proteome analysis suggested that the majority of enzyme-activity regulation was not hierarchical but rather occurred through enzyme activity regulation. An abrupt light-on condition induced high-light-stress proteins. Transcript analysis showed distinct patterns for the light and dark periods. Glycogen gradually accumulated in the light and was rapidly consumed in the last quarter of the dark period. This suggests that the circadian clock primed the cellular machinery for immediate resumption of growth in the light. Understanding cyanobacterial physiology in a diel environment is of interest to understand circadian regulation in general and for the utilization of these organisms in biotechnological applications. Our exploration of the effect of a diel light cycle on a cyanobacterial culture started with the wish to investigate the response of the metabolic network of the cells to the imposed repetitively fluctuating environment,...

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Marine sponges are relatively less explored for their chemical features but highly anticipated resource for bioactive compounds. In this paper we report the screening of marine sponges crude extracts for their potential to bind the adenosine A1 receptor. Many samples showed very promising activity and in order to identify the active components, a metabolomics-chemometrics approach is employed. Nuclear magnetic resonance spectroscopy is used for the metabolic profiling of the marine sponges and partial least squares (PLS) and orthogonal PLS (OPLS) algorithms are used to correlate the metabolomics with bioactivity data. Using several two dimensional-NMR techniques, the resonances responsible for the separation of high activity samples from the medium and low activity samples were identified as associated to metabolites like halisulfate 1, halisulfate 3-5, and suvanine (1-5), all belongs to sesterterpenes class. The reference compounds for these metabolites are also tested for the activity, which endorse the findings of the applied methodology.

The identification of active ingredients in crude plant extracts offers great advantages. In this study, nuclear magnetic resonance and chemometrics were used for the screening of in vitro anti-TNFα activity in different berry types. Solid phase extraction was applied and the resulting water, methanol–water (1:1), and methanol fractions were tested for the activity. The methanol–water fraction contained most of the phenolics and showed significantly higher activity than the other two fractions. In the second phase of this study, grapes from ‘Trincadeira’, ‘Touriga Nacional’, and ‘Aragonês’, at four developmental stages were metabolically classified and tested for the TNFα inhibition. The initial stages of grape development, green and veraison, were found more active against TNFα production as compared to the later ripe and harvest stages. Among the cultivars, ‘Touriga Nacional’ was found to be the most potent inhibitor. Different multivariate data analyses algorithms based on projections to latent structures were applied to correlate the NMR and TNFα inhibition data. The variable importance in the projections plot showed that phenolics like quercetin, myricetin, (+)-catechin, (−)-epicatechin, caftarate, and coutarate, were positively correlated with high activity. This work demonstrates the great potential of NMR spectroscopy in combination with chemometrics for the screening of large set of crude extracts, to study the effects of different variables on the activity, and identifying active compounds in complex mixtures like plant extracts.Electronic supplementary materialThe online version of this article (doi:10.1007/s11306-012-0406-8) contains supplementary material, which is available to authorized users.

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