Pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) has great potential within environmental analysis. This technique is mainly used for the chemical identification of macromolecules that cannot be characterized by either liquid or gas chromatography due to their big size. Through pyrolysis (controlled thermal degradation), these macromolecules are broken down into simpler molecules that can be separated by gas chromatography and detected by mass spectrometry. This technique has been traditionally used in environmental samples for the characterization of organic matter and humic substances, contaminants, lignins, etc. It attains the identification of the different types of chemical units that integrate the macromolecules. In addition, recently, this technique has experienced an important boom in the chemical characterization of microplastics present in environmental samples. This has triggered its use in this type of matrix. We describe the fundamentals and modalities of Py-GC-MS and outline some of the recent applications for the environmental analysis with special emphasis on humic substances and/or other types of organic matter components as well as microplastics, but reporting also other interesting application of environmental relevance.

Pyrolysis gas chromatography-mass spectrometry in environmental analysis: Focus on organic matter and microplastics

Systems and synthetic biology for the biotechnological application of cyanobacteria.

Characterization of natural organic matter in drinking water: Sample preparation and analytical approaches

Systematic overexpression study to find target enzymes enhancing production of terpenes in Synechocystis PCC 6803, using isoprene as a model compound.

Challenges and opportunity of recent genome editing and multi-omics in cyanobacteria and microalgae for biorefinery.

Cyanobacteria are phototrophic prokaryotes that convert inorganic carbon as CO2 into organic compounds at the expense of light energy. They need only inorganic nutrients and can be cultivated to high densities using non-arable land and seawater. This has made cyanobacteria attractive organisms for the production of biofuels and chemical feedstock. Synechocystis sp. PCC 6803 is one of the most widely used cyanobacterial model strains. Based on its available genome sequence and genetic tools, Synechocystis has been genetically modified to produce different biotechnological products. Efficient isoprene production is an attractive goal because this compound is widely used as chemical feedstock. Here, we report on our attempts to generate isoprene-producing strains of Synechocystis using a plasmid-based strategy. As previously reported, a codon-optimized plant isoprene synthase (IspS) was expressed under the control of different Synechocystis promoters that ensure strong constitutive or light-regulated ispS expression. The expression of the ispS gene was quantified by qPCR and Western blotting, while the amount of isoprene was quantified using GC—MS. In addition to isoprene measurements in the headspace of closed culture vessels, single photon ionization time-of-flight mass spectrometry (SPI-MS) was applied, which allowed online measurements of isoprene production in open-cultivation systems under various conditions. Under standard conditions, a good correlation existed between ispS expression and isoprene production rate. The cultivation of isoprene production strains under NaCl-supplemented conditions decreased isoprene production despite enhanced ispS mRNA levels. The characterization of the metabolome of isoprene-producing strains indicated that isoprene production might be limited by insufficient precursor levels. Transcriptomic analysis revealed the upregulation of mRNA and regulatory RNAs characteristic of acclimation to metabolic stress. Our best production strains produced twofold higher isoprene amounts in the presence of low NaCl concentrations than previously reported strains. These results will guide future attempts to establish isoprene production in cyanobacterial hosts.

/pdf/insights-into-isoprene-production-using-the-cyanobacterium-1obfx1lswc.pdf

Insights into isoprene production using the cyanobacterium Synechocystis sp. PCC 6803

Application of pyrolysis–mass spectrometry and pyrolysis–gas chromatography–mass spectrometry with electron-ionization or resonance-enhanced-multi-photon ionization for characterization of crude oils

Pyrolysis-gas chromatography-mass spectrometry with electron-ionization or resonance-enhanced-multi-photon-ionization for characterization of polycyclic aromatic hydrocarbons in the Baltic Sea.

With the effects of global warming the input of terrigenous material into the oceans is increasing, with unknown consequences for the ecosystem. The Baltic Sea is an ideal research object and observed effects can be transferred to the oceans. This paper combines the influence of biotic and abiotic factors especially for terrigenous dissolved organic matter (tDOM). The study is focused on specific lignin target molecules and reflects the influence of salinity and microbial activity. Samples were taken along the salt gradient. In addition, an incubation experiment, mixing of tDOM-rich river water with Baltic Sea water from three different stations, was carried out. A newly developed pyrolysis gas chromatography mass spectrometry (Py-GC/MS) method using two different mass selective analyzers in one measurement cycle was established for the analysis of tDOM species. It enables the characterization of natural samples by a universal (electron ionization quadrupole MS) as well as an aromatic fingerprint (resonance-enhanced-multi-photon-ionization time-of-flight MS). By thermal desorption (TD) and subsequent pyrolysis the free volatile and high molecular weight structures are accessible. A huge part of the chemical species exists as high molecular structures. The salt content has a high influence on the composition of DOM. Generally, under TD conditions greater changes were observed, especially for the incubation experiment. Under pyrolysis and the chosen experimental conditions, the lignin apparently is hardly degraded by microorganisms.

/pdf/pyrolysis-gas-chromatography-mass-spectrometry-with-electron-4jvh4zvams.pdf

Pyrolysis-gas chromatography-mass spectrometry with electron-ionization and resonance-enhanced-multi-photon-ionization for the characterization of terrestrial dissolved organic matter in the Baltic Sea

Sabrina Erdmann

Papers

Insights into isoprene production using the cyanobacterium Synechocystis sp. PCC 6803

Application of pyrolysis–mass spectrometry and pyrolysis–gas chromatography–mass spectrometry with electron-ionization or resonance-enhanced-multi-photon ionization for characterization of crude oils

Pyrolysis-gas chromatography-mass spectrometry with electron-ionization or resonance-enhanced-multi-photon-ionization for characterization of polycyclic aromatic hydrocarbons in the Baltic Sea.

Pyrolysis-gas chromatography-mass spectrometry with electron-ionization and resonance-enhanced-multi-photon-ionization for the characterization of terrestrial dissolved organic matter in the Baltic Sea