VAAM-Jahrestagung 2012 18.–21. März in Tübingen

155OTP079Oil degradation by Alcanivorax borkumensis - Understandingstress response networks in relation to catabolic performanceD.J. Näther* 1,2,3 , H.J. Heipieper 4 , K.N. Timmis 2,31 Goethe-University, Molecular Biosciences, Frankfurt, Germany2 Helmholtz Centre for Infection Research, Environmental Microbiology,Braunschweig, Germany3 Technical University Braunschweig, Institute for Microbiology, Braunschweig,Germany4 Helmholtz Centre for Environmental Research, Department EnvironmentalMicrobiology, Leipzig, GermanyThe recent Gulf of Mexico oil spill about two years ago has once againshown the urgent need for simple and efficient bioremediation techniquesthat can be quickly implemented on a large scale. The unprecedentedcontinuous flow of crude oil into the Gulf of Mexico presented a hugechallenge to existing oil-spill treatment methods, and current technologieswere not able to cope with the size and nature of the oil spill. Althoughgeneral interest about polluted environments has lessened over the pastdecade, it is nonetheless necessary to make controlled interventions andavoid pollution damage.A distinct group of members of the Oceanospirillales have a high affinitytowards oil hydrocarbon substrates in seawater. The dominating species inthis community is Alcanivorax borkumensis (Yakimov et al., 1998), whichhas been studied intensely for its bioremediation potential (Gertler et al.,2009, 2010). Unfortunately various stress conditions that naturally can befound in seawater, were so far not taken into account for bioremediation studies.The aim of our project is to understand stress and survival to finallyimprove catabolic performance in the field and find optimal formulations.For Alcanivorax borkumensis a microarray design was constructed to gaininsight into stress networks under environmental conditions. First stressresponsenetworks and the post-translational regulation of stress responsemechanisms were revealed.Also membrane fatty acid composition was investigated and a mechanismto cope harsh stress conditions was found. Finally first attempts for arobust formulation of Alcanivorax borkumensis were started with the aimto use those formulations in field trials for oil spills.Gertler C, Gerdts G, Timmis KN & Golyshin PN (2009) Microbial consortia in mesocosm bioremediationtrial using oil sorbents, slow-release fertilizer and bioaugmentation.FEMS Microbiol Ecol69: 288-300.Gertler C, Näther DJ, Gerdts G, Malpass MC & Golyshin PN (2010) A Mesocosm Study of the Changes inMarine Flagellate and Ciliate Communities in a Crude Oil Bioremediation Trial.Microb Ecol60: 180-191.Yakimov MM, Golyshin PN, Lang S, Moore ER, Abraham WR, Lunsdorf H & Timmis KN (1998)Alcanivorax borkumensis gen. nov., sp. nov., a new, hydrocarbon-degrading and surfactant producingmarine bacterium. Int J Syst Bacteriol 48: 339-348.OTP080Development of an in situ remediation technology for BTEXcontaminatedgroundwater by the use of iron oxide nanoparticlesC. Meyer*, J. Bosch, J. Braunschweig, A. Meyer, R.U. MeckenstockHelmholtz Zentrum München, Institut für Grundwasserökologie,Neuherberg, GermanyIron oxides play an important role in the global biogeochemical cycles. Inrecent years, a lot of iron-reducing bacterial strains were discovered and itbecame obvious that dissimilatory Fe(III) reduction plays a significant rolein anaerobic respiration processes in anoxic subsurface environments. Thereduction of Fe(III) is coupled to the oxidation of natural organic matter ororganic pollutants, whereby carbon dioxide is produced.However, Fe(III)in natural iron oxide minerals is poorly soluble, shows a high crystallinityand is thus hardly bioavailable for microorganisms.A recent study showed that colloidal iron oxide nanoparticles exhibit anexceptionally high reactivity compared to the reactivity of macro-sizedferric iron present in bulk phases (Bosch et al., 2010).Here, we want to use this high reactivity of iron oxide colloids for a newremediation technology for BTEX-polluted groundwater horizons.Eventually, our aim is to produce highly reactive iron oxide colloids whichcan be injected into a contaminant plume in order to stimulate themicrobial iron reduction and degradation of contaminants.In initial growth batch experiments cells of Geobacter metallireducens orGeobacter toluenoxydans were concentrated to high density, repeatedlywashed and added to toluene containing reaction medium with Fe(III)either in the macromolecular state or in the nanosized form. Iron reductionwas constantly measured over a period of around 1000 h, using a ferrozineassay for Fe(II) formation. Besides, toluene-degradation was analysed byGC-MS measurements and carbon isotope fractionation. Theseexperiments demonstrated that the addition of nanosized ferrihydriteenhanced the microbial toluene degradation, compared to thecorresponding bulk macroaggregates. Toluene was depleted almostcompletely by the use of nanosized ferrihydrite, whereas bulk ferrihydriteshowed no significant degradation.In the next step the iron oxide nanoparticles will be exposed in 2D-aquifersto examine their long-term stability as well as their long-term reactivity.Because of natural sediment as a matrix for the 2D-aquifer also a catalyticeffect is possible. As a last step we plan an outdoor test at a BTEXcontaminatedsite of a former industrial area.Bosch et al., 2010; Appl. Environ. Microbiol. 76:184-189.OTP081A new clean deletion and expression system for differentGluconobacter oxydans strainsD. Kostner*, M. Mientus, B. Peters, W. Liebl, A. EhrenreichTU München, Department of Microbiology, Freising-Weihenstephan, GermanyThe acetic acid bacterium Gluconobacter oxydans is well known for itsability to incompletely oxidize a great variety of carbohydrates, alcoholsand related compounds. In a multitude of biotechnological processes G.oxydans is used because of its regio- and stereo-selective oxidativepotential. The incomplete oxidation of substrates is catalyzed by variousmembrane-bound dehydrogenases.For the detailed investigation of Gluconobacter a well established andeasily applicable clean deletion system is essential.A method for markerless clean deletion in G. oxydans strain 621H isalready available from our group. This method is based on the use ofuracilphosphoribosyl transferase (UPRTase) as a counter-selectablemarker in the presence of the toxic pyrimidin analogue 5-fluorouracil (5-FU). The method is restricted to the usage of previously generated mutantsof the UPRTase gene (upp).To allow usage of wild-type strains instead of upp-mutants, wedeveloped an improved clean-deletion system using a cytosine-deaminaseas the counter-selectable marker in the presence of toxic 5-fluorocytosine(5-FC).In order to complement deletions of membrane bound dehydrogenases weconstructed a shuttle vector system for their functional expression. Thissystem was successfully used for the complementation of membranebound dehydrogenases in G. oxydans 621H and could also be used in otherG. oxydans strains. Furthermore this vector system is available for theexpression and characterization of membrane bound dehydrogenases froma vinegar metagenomeOTP082Will not be presented!OTP083Roast Duck with Curry Aromatized on Grapefruit Gravyor:How to Properly Keep Research RecordsF. Centler, B. Kiesel, S. Kleinsteuber, A. Kuppardt, T. Maskow, F. Zielinski*Helmholtz Centre for Environmental Research - UFZ, EnvironmentalMicrobiology, Leipzig, GermanyAny experimental work performed in a laboratory needs to be properlydocumented. Not only to assist a researcher in recalling each individualstep of an experiment after weeks, months, or even years, but also becausesomeday its results might become part of a publication. Therefore, keepinga laboratory notebook is a fundamental aspect of good scientific praxis,and a clearly written, self-explanatory lab book should be the standard.However, from our everyday experience with students, both new andadvanced in the lab, we have learned that a clear lab book does not comenaturally: dates are missing, objectives of experiments are not indicated,methods are not described in detail, reasons for certain procedures remainunclear, samples have been arbitrarily renamed, supplementary documentsnecessary for data interpretation are missing, loose notes, printouts, andphotocopies fall out when flicking through the lab book, interim results arenot documented, the writing is illegible, and so on. To alleviate thissituation and help our students to avoid the most common flaws, we haveformulated a few general guidelines on how to properly keep researchrecords that we think are particularly crucial. So far so good! However,modern psychology posits that guidelines are not well adopted as long theyare perceived as just another “dull instruction”. Besides, students arepotentially overloaded with “stuff to read and keep in mind”. Therefore,we were especially concerned with the task on how to get our points acrosswithout creating a feeling of something that “must” be followed or“should” be done, without being boring, and without being wiped out ofmemory shortly after reading. We encountered this challenge by (i)visually exemplifying our points in the form of a poster, (ii) wrapping ourguidelines into a humorous story of metaphoric character, and (iii) placingthe poster in the lab floor, thereby reminding our students of the mostimportant points on a daily basis. Our poster entitled “Roast Duck withCurry Aromatized on Grapefruit Gravy” features a young scientist whokeeps a cook book to keep record of her attempts to fix a decent dinner forfriends at her place, eventually doing everything right, except for … Tofind out come and see our poster!BIOspektrum | Tagungsband 2012