Physiological function of the maltose operon regulator, MalR, in Lactococcus lactis

BACKGROUND: Maltose metabolism is initiated by an ATP-dependent permease system in Lactococcus lactis. The subsequent degradation of intracellular maltose is performed by the concerted action of P(i)-dependent maltose phosphorylase and β-phosphoglucomutase. In some Gram-positive bacteria, maltose metabolism is regulated by a maltose operon regulator (MalR), belonging to the LacI-GalR family of transcriptional regulators. A gene presumed to encode MalR has been found directly downstream the maltose phosphorylase-encoding gene, malP in L. lactis. The purpose of this study was to investigate the physiological role of the MalR protein in maltose metabolism in L. lactis. RESULTS: A L. lactis ssp. lactis mutant, TMB5004, deficient in the putative MalR protein, was physiologically characterised. The mutant was not able to ferment maltose, while its capability to grow on glucose as well as trehalose was not affected. The activity of maltose phosphorylase and β-phosphoglucomutase was not affected in the mutant. However, the specific maltose uptake rate in the wild type was, at its lowest, five times higher than in the mutant. This difference in maltose uptake increased as the maltose concentration in the assay was increased. CONCLUSION: According to amino acid sequence similarities, the presumed MalR is a member of the LacI-GalR family of transcriptional regulators. Due to the suggested activating effect on maltose transport and absence of effect on the activities of maltose phosphorylase and β-phosphoglucomutase, MalR of L. lactis is considered rather as an activator than a repressor

Randomly amplified polymorphic DNA (RAPD) typing of Salmonella Senftenberg in animal feed production.

Randomly Amplified Polymorphic DNA (RAPD) was studied as genotyping method typing for a strain collection of Salmonella, belonging to the serotype Senftenberg. This collection consisted of 48 strains/isolates that were sampled in Sweden during 1995-96. In this study the aim was evaluate the usefulness of RAPD in terms of discriminatory power, reproducibility and typeability to compare it with other genotyping methods. By using Taq and Tth DNA polymerase in separate reactions the ability to increase discriminatory power and reproducibility was studied. When Tth DNA polymerase was used in the RAPD reaction brighter bands were obtained and the reproducibility was increased. The results suggest that RAPD can be used for rapid screening of a strain material and in combination with other more discriminating genotyping methods to more truly reflect the genetic diversity

Comparison of heterologous xylose transporters in recombinant Saccharomyces cerevisiae

Abstract Background Baker's yeast (Saccharomyces cerevisiae) has been engineered for xylose utilization to enable production of fuel ethanol from lignocellulose raw material. One unresolved challenge is that S. cerevisiae lacks a dedicated transport system for pentose sugars, which means that xylose is transported by non-specific Hxt transporters with comparatively low transport rate and affinity for xylose. Results In this study, we compared three heterologous xylose transporters that have recently been shown to improve xylose uptake under different experimental conditions. The transporters Gxf1, Sut1 and At5g59250 from Candida intermedia, Pichia stipitis and Arabidopsis thaliana, respectively, were expressed in isogenic strains of S. cerevisiae and the transport kinetics and utilization of xylose was evaluated. Expression of the Gxf1 and Sut1 transporters led to significantly increased affinity and transport rates of xylose. In batch cultivation at 4 g/L xylose concentration, improved transport kinetics led to a corresponding increase in xylose utilization, whereas no correlation could be demonstrated at xylose concentrations greater than 15 g/L. The relative contribution of native sugar transporters to the overall xylose transport capacity was also estimated during growth on glucose and xylose. Conclusions Kinetic characterization and aerobic batch cultivation of strains expressing the Gxf1, Sut1 and At5g59250 transporters showed a direct relationship between transport kinetics and xylose growth. The Gxf1 transporter had the highest transport capacity and the highest xylose growth rate, followed by the Sut1 transporter. The range in which transport controlled the growth rate was determined to between 0 and 15 g/L xylose. The role of catabolite repression in regulation of native transporters was also confirmed by the observation that xylose transport by native S. cerevisiae transporters increased significantly during cultivation in xylose and at low glucose concentration.</p

Virkesflöde och val av hjulsystem på virkesfordon inom Region Iggesund, Holmen Skog

Syftet med detta arbete har varit att undersöka hur virkesflödet från Region Iggesund varierar under året och belysa orsakerna till detta samt att beräkna transportkostnader och analysera vilka distrikt som skulle kunna ha störst nytta av virkesfordon med Central Tyre Inflation (CTI) eller Super Singel hjul, alternativt hjulsystem som kombinerar de båda teknikerna. Utgångspunkten har varit rationell virkesförsörjning från skog till industri, med så låga virkeslager och transportkostnader som möjligt. Region Iggesund anskaffade 1,9 miljoner fastkubikmeter (m3fub) virke 2011, varav 45 % kom från egen skog och 55 % kom från lokala köp. Huvuddelen levererades till Iggesunds Bruk, Iggesunds Såg och Hallsta Pappersbruk. Regionen är uppdelat i sex distrikt, med Uppland i söder, Sveg i nordväst och Hudiksvall i öster. Däremellan ligger Bollnäs, Delsbo och Ljusdal. Studien avser 2010 och 2011, men omfattar inte Bollnäs distrikt eftersom detta var nybildat och nödvändiga uppgiftsunderlag saknades. Den inmätta volymen från egen skog respektive lokala köp är varandras spegelbilder med lägst leverans från egen skog under de bästa drivningssäsongerna och vice versa. Orsaken är främst att man vill undvika skador på skogsmark och vägar hos privata skogsägare, vilket skulle kunna inverka negativt på köpverksamheten. Väglagret är högst i februari, ca 7,5 % av årsvolymen, och lägst i oktober, ca 2,5 %. Distriktens medeltransportavstånd till industri varierar från 38 km till 192 km. Variationen under året när det gäller skotade och inmätta volymer har beskrivits med hjälp av variationskoefficienten. Denna var i genomsnitt 17 % respektive 12 %, men varierade mellan distrikt. Variationen i inmätt volym från distrikten minskade med ökad andel av årsvolymen. Däremot kunde inte något samband med vägstandard påvisas. Förklaringen är troligen att verksamheten i hög grad anpassats till den rådande vägsituationen. Sambandet mellan inmätt och skotad volym var starkare vid kortare transportavstånd och vice versa, vilket torde kunna förklaras av distriktens taktiska roll i virkesförsörjningen. För ett konventionellt 60 tons fordon som utrustats med CTI ökade transportkostnaden med i genomsnitt 1,5 % eller 1 kr/m3fub. Super Singel hjul innebar däremot en kostnadssänkning med i genomsnitt 1,3 % eller 1,2 kr/m3fub. Effekten på transportkostnaden är med andra ord begränsad. Mot detta skall ställas effekter på virkesflöde och vägar. Fördelen med CTI är främst ökad framkomlighet, minskad spårbildning och minskat vägslitage. Därför är nyttan av CTI störst på vägar som har låg tillgänglighet under tjällossningen och/eller är svaga under regniga perioder. Korta transportavstånd, som innebär hög volym per fordon samt gruppkörning, som kan innebära risk för utmattning av vägen under känsliga perioder, är också förutsättningar som talar för CTI. Fördelen med Super Singel hjul är att det sänker bränsleförbrukningen och därmed transportkostnaden. Analyserna visade att Delsbo och Hudiksvall är av störst intresse för CTI medan Uppland är intressant för Super Singel hjul. CTI är också ett bra alternativ för Ljusdal. Sveg har långa transportavståndet och relativt låg vägstandard, därför är bedömningen att Super Singel hjul skulle kunna kombineras med CTI. Detta är dock ett i praktiken obeprövat hjulsystem i Sverige. Vid införande av 74 tons bruttovikt, som nu är aktuellt, så kommer transportkostnaden att kunna sänkas. Den relativa förändringen av transportkostnaden vid införande av CTI och Super Singel hjul förblir dock oförändrad. Detta innebär att tröskeln för införande av dessa tekniker sänks. Variationen i virkesflödet under året, beroende på skillnader i vägstandard och övriga förutsättningar för virkesförsörjningen inom Region Iggesund, visar att det finns en potential att differentiera fordonen och bättre anpassa dessa till uppgiften. En ökad specialisering kan dock kräva mer planering och intensivare transportledning. Detta kan förväntas sätta ökat fokus på utvecklingen av hela transportsystemet, d.v.s. vägar och fordon, vilket i sig är positivt. Mot bakgrund av detta föreslås en bredare implementering av CTI och även test av Super Singel hjul där förutsättningar finns. En nyckelförutsättning är då troligen ökat samarbete med åkeriföretagen och mer innovationsdrivande upphandling av transporttjänster.The aim of this work was to investigate how the timber flows from Region Iggesund vary during the year, highlighting the reasons for this, and to calculate transportation costs and analyze which districts could benefit most from timber vehicles with Central Tyre Inflation (CTI) or Super Single wheel, or wheel system that combines the two techniques. The starting point has been streamlined wood supply from forest to industry, with as low wood storage and transportation costs as possible. Region Iggesund procured 1.9 million cubic meters of solid wood under bark (m3sub) in 2011, of which came 45 % from own forests and 55 % came from local purchases. The majority was delivered to Iggesund Paper Mill, Iggesund Saw Mill and Hallsta Paper Mill. The region is divided into six districts, with Uppland in the south, Sveg in the northwest and Hudiksvall in the east. In between lies Bollnäs, Delsbo and Ljusdal. The study refers to 2010 and 2011, but does not include the Bollnäs district because it was newly formed and necessary supporting data was lacking. The measured volume from own forests and local purchases are mirror images with the lowest delivery from own forests under the best logging seasons and vice versa. This is mainly motivated by the need to avoid damage to woodlands and roads of private forest owners, which otherwise could have a negative effect on local timber purchases. The storage of wood at road side had its maximum in February, about 7.5 % of the annual volume, and its lowest level in October, about 2.5 %. The average transport distance from district to the industry varied from 38 km to 192 km. The variation during the year for terrain transported and measured volumes at mill have been described using the coefficient of variation. This was on average 17 % and 12 % respectively, but varied between districts. The variation in the measured volume from the districts decreased with increasing proportion of the total annual volume from Region Iggesund. However, no relationship with the standard of roads was found. The explanation for this is probably that the harvest planning, to a large extent, has adapted to the existing road situation. The correlation between the measured volume at mill and the terrain transported volume is stronger at shorter transport distances and vice versa, which probably could be explained by the tactical role of different districts in wood supply. For a conventional 60-tonne vehicle equipped with CTI the transportation cost increased by on average 1.5 % or 1 SEK per m3sub. Super Single wheel, on the contrary, gives a reduction in transportation costs by on average 1.3 % or 1.2 SEK per m3sub. The effect on transportation cost was in other words limited. Against this must be set effects on timber flow and roads. The advantage of CTI is mainly increased accessibility, reduced rutting and reduced road wear. Therefore, the benefits of CTI are greatest on roads that have low availability during the spring thaw and/or weakness during rainy periods. High annual volume per vehicle, thanks to short transportation distance and group riding, which may pose a risk of fatigue of the roads during sensitive periods, are also conditions that speaks for CTI. The advantage of Super Single wheel is that it reduces fuel consumption and hence transportation costs. The analyze show that Delsbo and Hudiksvall are of most interest for CTI, while Uppland is interesting for Super Single wheel. CTI is also a good option for Ljusdal. Sveg has long transportation distances and relatively low road standard, therefore, the assessment is that Super Single wheels could be combined with CTI. However, this wheel system has not been tested in Sweden. When introducing 74 tons gross vehicle weight, which is now imminent, the transportation cost will be reduced. However the relative change of the transportation cost when introducing CTI and Super Single wheel will remain unchanged. This means that the threshold for the introduction of these technologies is lowered. The variation in the timber flow during the year, due to differences in road standard and other requirements for wood supply at Region Iggesund, shows that there is a potential to differentiate vehicles and better adapt them to the task in timber supply. Increased specialization may require more planning and more intensive transport management. This can be expected to put increased focus on the development of the whole transportation system, i.e. roads and vehicles, which in itself is positive. In light of this, the suggestion is a broader implementation of CTI and also testing of Super Single wheels where favorable conditions exist. A key prerequisite is then probably closer cooperation with haulage companies and more innovation-driven procurement of transportation services

Värden i samhällsstyrningen - En studie om sociala hänsyn vid offentlig upphandling

The ‘New Public Management’ wave of the 90s is considered to have had a great impact on the values that control the Swedish public administration. Arguably, it has led to an increased representation of economic values within the public administration and, as a result, democratic values have been neglected. This qualitative case study has analyzed the democratic and economic values within the public procurement with social considerations in a municipal owned company. The aim has been to enlighten which values that are represented in the governance of public procurement with social considerations. The empirical material consists of interviews, which have been interpreted from a perspective of economic and democratic values. The study has shown that several aspects of economic and democratic values are both believed to be fulfilled within the process of public procurement with social considerations. This result has led to the conclusion that the aim of introducing social considerations within the public procurement is likely an example of a development towards a more complex public administration. In which, both economic and democratic values are expected to be fully represented within the public administration

Development of an in vitro method for detection of Clostridium botulinum types A and E using real-time PCR

Specific primers for C. botulinum types A and E neurotoxin genes were evaluated both from the literature and of own construction. Furthermore, a real-time system with specific hybridisation probes was designed for C. botulinum type E neurotoxin gene, and is under construction for type A. Sequencing of part of the neurotoxin gene for type E showed some differences with sequences reported in GenBank. The PCR methods were optimised regarding amplification efficiency, linear range and specificity. The detection limit for type E using real-time PCR is at least 0,1 ng/ml, corresponding to 0,4 pg of total DNA in the tube, and at least 0,5 ng/ml (2,5 pg of total DNA) for type A using conventional PCR. Quantitative reverse transcription PCR was used to study the relative expression of the neurotoxin gene in different growth phases

A set-valued framework for birth-and-growth process

We propose a set-valued framework for the well-posedness of birth-and-growth process. Our birth-and-growth model is rigorously defined as a suitable combination, involving Minkowski sum and Aumann integral, of two very general set-valued processes representing nucleation and growth respectively. The simplicity of the used geometrical approach leads us to avoid problems arising by an analytical definition of the front growth such as boundary regularities. In this framework, growth is generally anisotropic and, according to a mesoscale point of view, it is not local, i.e. for a fixed time instant, growth is the same at each space point

Jämställdhet i EU - En fallstudie om politisk påverkan och europeisk integration

Europeiska unionen (EU) utgör idag en inflytelserik plattform för att utöva politisk påverkan, något som har dragit till sig ett stort antal aktörer. Många nya politiska kanaler och möjligheter har öppnats upp i och med det europeiska samarbetet, men hur kan organisationer gå till väga för att faktiskt kunna påverka den politik som förs inom EU:s institutioner? Denna uppsats är en fallstudie av organisationen European Women´s Lobby och deras arbete för att förbättra kvinnors representation i EU. Deras arbete undersöks genom en analys av det officiella material som presenterar en av de kampanjer som organisationen driver på den europeiska plattformen. Till hjälp för denna analys användes ett teoretiskt ramverk som bygger på europeiseringsteori. Det som undersökningen har visat på är att olika aspekter av europeisering anses ha skapat både nya möjligheter samt svårigheter för att utforma och bedriva den kampanj som har studerats