LNG-fueled vessels in the Norwegian short-sea market : a cost-effective response to environmental regulation

The objective of this thesis is to assess the environmental and economic advantages of using LNG as fuel for ships. Air emissions from ships are an increasing environmental concern. Since the shipping sector can expect to face more stringent environmental regulations in the future, LNG’s potential as a response to these regulations is analyzed. This study offers an overview of present environmental regulations as well as a description of the properties of LNG. The aim of the final analysis is to identify the cost position of LNG-fueled vessels within different sectors of the Norwegian short-sea shipping market. Net present value (NPV) analysis sets the technical framework for the economic evaluation. The analysis comes to the conclusion that using LNG as fuel for ships offers the potential for significant environmental improvement, regarding both air quality and climate protection, in all sectors subject to the analysis. Economically, LNG as fuel can compete with conventional marine fuel (MGO), at oil prices around approximately 60 $/bbl. Hence, the results of this study indicate that from both an environmental- and economic perspective the investment in LNG powered ships is strongly recommendable. The study also presents some potential barriers with regards to commercial viability and technological feasibility that need to be overcome before LNG becomes fully competitive with other fuels

Chassis organism from Corynebacterium glutamicum – a top-down approach to identify and delete irrelevant gene clusters

Unthan S, Baumgart M, Radek A, et al. Chassis organism from Corynebacterium glutamicum – a top-down approach to identify and delete irrelevant gene clusters. Biotechnology Journal. 2015;10(2):290-301

Plasma lipid profiles discriminate bacterial from viral infection in febrile children

Fever is the most common reason that children present to Emergency Departments. Clinical signs and symptoms suggestive of bacterial infection are often non-specific, and there is no definitive test for the accurate diagnosis of infection. The 'omics' approaches to identifying biomarkers from the host-response to bacterial infection are promising. In this study, lipidomic analysis was carried out with plasma samples obtained from febrile children with confirmed bacterial infection (n = 20) and confirmed viral infection (n = 20). We show for the first time that bacterial and viral infection produces distinct profile in the host lipidome. Some species of glycerophosphoinositol, sphingomyelin, lysophosphatidylcholine and cholesterol sulfate were higher in the confirmed virus infected group, while some species of fatty acids, glycerophosphocholine, glycerophosphoserine, lactosylceramide and bilirubin were lower in the confirmed virus infected group when compared with confirmed bacterial infected group. A combination of three lipids achieved an area under the receiver operating characteristic (ROC) curve of 0.911 (95% CI 0.81 to 0.98). This pilot study demonstrates the potential of metabolic biomarkers to assist clinicians in distinguishing bacterial from viral infection in febrile children, to facilitate effective clinical management and to the limit inappropriate use of antibiotics

Novel insights into characteristics, relevance and regulation of corynebacterial aconitase

Strains of the Gram-positive soil bacterium $\textit{Corynebacterium glutamicum}$ are widely used in industrial biotechnology for the production of amino acids, predominantly L-glutamate and L-lysine. In this context, the tricarboxylic acid cycle (TCA cycle) is of particular interest, as it provides energy and the biosynthetic precursors 2-oxoglutarate and oxaloacetate. A detailed understanding of the enzymes and of the regulation of this metabolic pathway is crucial for rational improvement of production strains. In this dissertation, the properties, physiological relevance and regulation of aconitase, a [4Fe-4S]-cluster containing enzyme catalysing the second step of the TCA cycle, have been investigated. In the first part of this thesis, the biochemical properties of aconitase were studied. The comparison of different enzyme assays revealed the highest activity for the hydration of $\textit{cis}$-aconitate (0.433 ± 0.054 U mg$^{-1}$ protein in cell-free extracts) and the lowest activity for the physiological reaction from citrate to isocitrate (0.134 ± 0.026 U mg$^{-1}$). Aconitase was heterologously overproduced, purified, reactivated and used for the determination of kinetic constants. The K$_{m}$ values for citrate (480 ± 200 μM) and isocitrate (552 ± 302 μM) were much higher than the one for $\textit{cis}$-aconitate (18.5 ± 3.4 μM), a feature reported also for aconitases from other organisms. The pH and temperature optima were found to be between 7.5 and 7.75 and at 50°C. These results are useful for mechanistic in $\textit{silico}$ models of the central metabolism of $\textit{C. glutamicum}$. The second aim of this thesis was to study the impact of an aconitase deletion on growth and metabolism of $\textit{C. glutamicum}$. A $\Delta \textit{acn}$ strain was found to be glutamate-auxotrophic and severely inhibited in its growth. It secreted large amounts of acetate into the medium and showed strongly elevated mRNA and protein levels of enzymes involved in acetate metabolism. When searching for the reason of acetate production, we discovered that the $\Delta \textit{acn}$ strain was lacking citrate synthase activity due to a single point mutation in the corresponding $\textit{gltA}$ gene. Subsequent analysis of 28 independent $\Delta \textit{acn}$ mutant strains revealed that 16 of them contained none or only inactive citrate synthase due to 16 different kinds of mutations (point mutations, insertions, deletions, transposon insertions). This result clearly showed that in $\Delta \textit{acn}$ mutants there is a strong selection pressure for secondary mutations in the $\textit{gltA}$ gene, probably caused by the toxicity of high cytoplasmic citrate concentrations that accumulate in the absence of aconitase. Similar results were obtained for $\textit{C. glutamicum}$ mutants lacking the $\textit{icd}$ gene encoding isocitrate dehydrogenase. In this case, 8 out of 25 $[...

LNG-fueled vessels in the Norwegian short-sea market : a cost-effective response to environmental regulation

The objective of this thesis is to assess the environmental and economic advantages of using LNG as fuel for ships. Air emissions from ships are an increasing environmental concern. Since the shipping sector can expect to face more stringent environmental regulations in the future, LNG’s potential as a response to these regulations is analyzed. This study offers an overview of present environmental regulations as well as a description of the properties of LNG. The aim of the final analysis is to identify the cost position of LNG-fueled vessels within different sectors of the Norwegian short-sea shipping market. Net present value (NPV) analysis sets the technical framework for the economic evaluation. The analysis comes to the conclusion that using LNG as fuel for ships offers the potential for significant environmental improvement, regarding both air quality and climate protection, in all sectors subject to the analysis. Economically, LNG as fuel can compete with conventional marine fuel (MGO), at oil prices around approximately 60 $/bbl. Hence, the results of this study indicate that from both an environmental- and economic perspective the investment in LNG powered ships is strongly recommendable. The study also presents some potential barriers with regards to commercial viability and technological feasibility that need to be overcome before LNG becomes fully competitive with other fuels

Communities of Niche-Optimized Strains: Small-Genome Organism Consortia in Bioproduction

Bacterial genome reduction is a common phenomenon in nature that has also inspired several projects with biotechnologically relevant organisms. In many cases, however, no performance improvements with the streamlined chassis were obtained. A comparative analysis of natural and synthetic reduced genomes and their corresponding ecological niches reveals that: (i) deleting expressed genes can lead to noticeable energy conservation usable for improved biomass or product synthesis; and (ii) the simplified strains depend on the environment (e.g., another community member) to complement deleted functions. Based on this analysis, we introduce the concept of Community of Niche-optimized Strains (CoNoS) as an alternative strategy to generate superior biotechnological production processes