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Serratia sp. ATCC 39006 (S39006) is known for producing carbapenem and prodiginine antibiotics; 1-carbapen-2-em-3-carboxylic acid (car) and prodigiosin. It displays different motility mechanisms, such as swimming and swarming aided by flagellar rotation and biosurfactant production. In addition, S39006 produces gas vesicles to float in aqueous environments and enable colonization of air-liquid interfaces. Gas vesicles are thought to be constructed solely from proteins expressed from a gene cluster composed of two contiguous operons, gvpA1-gvpY and gvrA-gvrC. Prior to this study, three cognate regulators, GvrA, GvrB, and GvrC, encoded by the right hand operon were known to be essential for gas vesicle synthesis. Post-transcriptional regulators such as RsmA-rsmB were also known to be involved in the inverse regulation of gas vesicles and flagella based motility. Furthermore, gas vesicle formation, antibiotic production, and motility in S39006 were affected by cell population densities and de-repressed at high cellular densities through a quorum sensing (QS) system. The aim of this research study was to identify novel regulatory inputs to gas vesicle production. Mutants were generated by random transposon mutagenesis followed by extensive screening, then sequencing and bioinformatic identification of the corresponding mutant genes. After screening, 31 mutants and seven novel regulatory genes impacting on cell buoyancy were identified. Phenotypic and genetic analysis revealed that the mutations were pleiotropic and involved in cell morphology, ion transport and central metabolism. Two new pleiotropic regulators were characterized in detail. Mutations in an ion transporter gene (trkH) and a putative transcriptional regulator gene (floR) showed opposite phenotypic impacts on flotation, flagella-based motility and prodigiosin, whereas production of the carbapenem antibiotic was affected in the transcription regulator mutant. Gene expression assays with reporter fusions, phenotypic assays in single and double mutants, and proteomics suggested that these regulatory genes couple different physiological inputs to QS and RsmA-dependent and RsmA-independent pathways.

Detta arbete i militärteknik studerar om högeffektpulsad mikrovågsstrålning kan uppnå verkan mot kommersiella UAV. Analysen genomförs på två olika icke-dödliga HPM-vapen. Data hämtas från ett scenario där vapenverkan innebär hög risk för skada på tredje man. En Försvarsmaktsstudie har konstaterat att Luftvärnsbataljon saknar förmåga att verka mot små UAV.Dagsaktuell kunskap har inhämtats om scenariots miljö samt från forskning och industri genom studiebesök. Inhämtad kunskap har möjliggjort en logisk-matematisk parameterstudie på ett scenario med militärtekniskt perspektiv. Analysens slutsatser är att kommersiella UAV innehar låg skyddsnivå, att beslut om insats underlättas i alla miljöer och att en elektronisk sköld i form av HPM-vapen skyddar en stor volym samtidigt. HPM-vapen kan inte som ensamt vapensystem stå för skydd och uppnå säkerställd verkan mot kommersiell UAV. HPM-vapen kan däremot komplettera övriga verkanssystem och göra luftförsvaret starkare genom system av system. HPM-vapen kan bidra till att minska ett befintligt förmågeglapp mot kommersiella UAV. / This paper in military technology discusses whether high power microwaves can affect commercial UAVs. Two non-lethal HPM-weapons are analyzed. The data is collected from a scenario where there is a high risk for collateral damage. A Swedish Armed Forces study stated that the Air Defence Battalion lacks ability to affect small UAVs. The latest knowledge is obtained from the environment in the scenario, from research and from the industry. This knowledge has enabled a logical-mathematical parametric study on the scenario within a military perspective. The result of the study is the assessment that commercial UAVs are assessed to have low protection factor, facilitates decision to act in all environments and provides an electronic shield protection of a large surface at the same time. HPM-weapons can´t stand as a single system for protection against commercial UAVs and achieve guaranteed effect. However, HPM-weapons can complement other weapon systems and thus make the air defense stronger through systems of systems. HPM-weapons can reduce the capability deficiency against commercial UAVs.

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No description available.