Influence of quorum sensing signal molecules on biofilm formation in Proteus mirabilis O18

The influence of basis of quorum sensing molecules on Proteus strains is much less known as compared to Pseudomonas or Escherichia. We have previously shown that a series of acylated homoserine lactones (acyl-HSL) does not influence the ureolytic, proteolytic, or hemolytic abilities, and that the swarming motility of Proteus mirabilis rods is strain specific. The aim of the presented study was to find out if the presence of a series of acyl-HSL influences biofilm formation of P. mirabilis laboratory strain belonging to O18 serogroup. This serogroup is characterized by the presence of a unique non-carbohydrate component, namely phosphocholine. Escherichia coli and P. mirabilis O18 strains used in this work contains cloned plasmids encoding fluorescent protein genes with constitutive gene expression. In mixed biofilms in stationary and continuous flow conditions, P. mirabilis O18 overgrow whole culture. P. mirabilis O18 strain has genetically proved a presence of AI–2 quorum sensing system. Differences in biofilm structure were observed depending on the biofilm type and culture methods. From tested acylated homoserine lactones (BHL, HHL, OHL, DHL, dDHL, tDHL), a significant influence had BHL on thickness, structure, and the amount of exopolysaccharides produced by biofilms formed by P. mirabilis O18 pDsRed2

The Two-Domain LysX Protein of Mycobacterium tuberculosis Is Required for Production of Lysinylated Phosphatidylglycerol and Resistance to Cationic Antimicrobial Peptides

The well-recognized phospholipids (PLs) of Mycobacterium tuberculosis (Mtb) include several acidic species such as phosphatidylglycerol (PG), cardiolipin, phosphatidylinositol and its mannoside derivatives, in addition to a single basic species, phosphatidylethanolamine. Here we demonstrate that an additional basic PL, lysinylated PG (L-PG), is a component of the PLs of Mtb H37Rv and that the lysX gene encoding the two-domain lysyl-transferase (mprF)-lysyl-tRNA synthetase (lysU) protein is responsible for L-PG production. The Mtb lysX mutant is sensitive to cationic antibiotics and peptides, shows increased association with lysosome-associated membrane protein–positive vesicles, and it exhibits altered membrane potential compared to wild type. A lysX complementing strain expressing the intact lysX gene, but not one expressing mprF alone, restored the production of L-PG and rescued the lysX mutant phenotypes, indicating that the expression of both proteins is required for LysX function. The lysX mutant also showed defective growth in mouse and guinea pig lungs and showed reduced pathology relative to wild type, indicating that LysX activity is required for full virulence. Together, our results suggest that LysX-mediated production of L-PG is necessary for the maintenance of optimal membrane integrity and for survival of the pathogen upon infection

Current standards in the design of high-voltage transmission towers. Testing of 220 kV towers

Pierwsza część artykułu to analiza porównawcza norm stosowanych w procesie projektowania napowietrznych linii elektroenergetycznych oraz wskazanie zasadniczych różnic w podejściu do obliczania wielkości obciążeń ich kombinacji i zasad wymiarowania konstrukcji. Druga część artykułu przedstawia krótką analizę badań wytrzymałościowo- -zniszczeniowych słupów linii 220 kV.The first part of this article consists of a comparative analysis of the standards applied in the process of designing overhead power lines, and indicates the principal differences in approaches to the calculation of the size of loads on combinations of such structures and principles for dimensioning. The second part contains a short analysis of strength and destruction testing carried out on the towers of a 220 kV power line

Dielectric Properties of Triglycine Sulphate Crystals Admixtured with L-Threonine

The influence of L-threonine admixture on the dielectric properties of triglycine sulphate (TGS) crystals was studied. With increasing concentration of the admixture in the solution from which the crystals were grown, their maximum permittivity and spontaneous polarization were found to decrease, their Curie point was found not much different than that for pure TGS crystals (322 K), the coercive field and bias field increased. The domain structure of the obtained crystals was also studied by the liquid crystal method

Analiza systemu oczyszczania ścieków miasta aglomeracji Śląskiej

The construction of the technological treatment plant is closely related to the amount and physicochemical parameters of incoming sewage. The economic aspects and the principles of sustainable development also should be taken into account at the stage of sewage treatment plant construction planning. Moreover, in large cities, there is often greater number of sewage treatment plants, which should create an effective system for wastewater treatment. Municipal wastewater treatment system should not disturb the ecological balance of the area and cannot contribute to the deterioration of the living conditions of people (especially those living in the immediate vicinity of the sewage treatment plant). The paper compares the process lines of three wastewater treatment plants located in the city of Bytom: “Centralna” plant, “Miechowice” plant and “Bobrek” plant. The paper also compares the main indicators of the efficiency of the described wastewater treatment plants and the selected parameters of the sewage sludge. Based on the above data, an attempt was made to assess the proper operation of the sewage treatment system in the city of Bytom.Budowa ciągu technologicznego oczyszczalni jest ściśle powiązana z ilością i parametrami fizykochemicznymi dopływających ścieków. Na etapie planowania należy rozważyć także kryteria zrównoważonego rozwoju oraz aspekty ekonomiczne. Ponadto, w dużych miastach na skuteczny system oczyszczania ścieków składa się często większa liczba oczyszczalni. Miejski system oczyszczania ścieków nie może zakłócać równowagi ekosystemowej danego obszaru ani przyczyniać się do pogorszenia warunków bytowania ludzi (szczególnie tych mieszkających w bezpośrednim sąsiedztwie oczyszczalni ścieków). W artykule porównano ciągi technologiczne trzech oczyszczalni ścieków znajdujących się na terenie miasta Bytom: Oczyszczalni „Centralna”, Oczyszczalni „Miechowice” oraz Oczyszczalni „Bobrek”. Zestawiono także główne wskaźniki efektywności oczyszczania oraz niektóre parametry osadu czynnego. Na podstawie powyższych danych podjęto próbę oceny prawidłowego funkcjonowania systemu oczyszczania ścieków w Bytomiu

Investigation of the Dependence of Dielectric Properties of D-Serine Admixtured TGS Crystals on the Distance from the Seed of the Crystal Growth

Dielectric properties of a D-serine admixtured triglycine sulphate (TGS) crystal were studied on samples cut out from different sites in the crystal. The value of spontaneous polarization P$\text{}_{s}$ measured on b-cuts was found to be independent of the site. Whereas the coercive field E$\text{}_{c}$ values were higher for the samples cut out closer to the seed than for those cut out at the ends of the crystal along b axis. After rejuvenation the values of the bias field E$\text{}_{b}$ increased in contrary to the effect observed in the pure TGS crystals. An exponentially decreasing dependence of the maximum permittivity ε$\text{}_{max}$ on the site of the samples (b-plates) cut out along b axis from -b to +b positions, was obtained

Biokompozyty przeszłość i przyszłość

Due to the increasing environmental awareness nowadays biocomposites are becoming as important and prevalent materials as they were centuries ago. The development of high-performance engineering products made from natural resources is increasing worldwide. Natural fibre composites have become more and more efficient as new compositions and their processing methods are being intensively researched, developed and consequently applied. This paper, above all, is intended to provide a brief outline of the development and modification trends which aim to make biocomposites more user-friendly and eco-friendly by means of novel processing methods. These methods produce biopolymers with an improved melt behaviour and use naturally occurring raw materials