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1

Enzymatic chitosan membranes for L-aspartic acid biosynthesis

100%
Modrzejwska Z., Chmiel A., Sobierajski B., Platak D., Kaminski W.
Biotechnologia
|
1998
|
issue 3
121-133
EN
A new method for the formation of enzymatic chitosan membranes containing active cells of E. coli mutant producing L-aspartic acid was developed. Trisodium orto-phosphate as a gelation agent for the chitosan membrane formation was proposed. The highest productivity, with near 100% conversion of ammonium fumarate to L-aspartic acid, has been shown by the membranes characterized by a low permeate stream flow of 5-10 dm3/m2h at an overpressure of 0,05 MPa.
2

Plasmids R577 and R785 decrease the resistance of Escherichia coli K12 strain W1485 to bactericidal action of normal serum

100%
Jankowski S., Cisowska A.
Journal of Applied Genetics
|
1998
|
vol. 39
|
issue 3
211-216
EN
The role of plasmids of drug resistance R577 and R785 in the development of susceptibility of Escherichia coli K12 strain W1485 to the bactericidal action of serum was studied. Plasmids R577 and R785 were transfered to cells of strain W1485 by means of conjugation. The susceptibility of cells containing the plasmid to serum was compared to that of cells lacking the plasmid. It was found that plasmids R577 and R758 sensitize bacteria to the action of serum.
3

Escherichia coli survival in the water from the Gulf of Gdansk under laboratory conditions

100%
Krolska M., Latala A., Michalska M., Nowacki J., Sobol Z.
Oceanological Studies
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1997
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vol. 26
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issue 4
133-143
EN
Faecal coliform bacteria (among others Escherichia coli) are routinely used in monitoring of water areas (first of all seaside resorts). Their occurrence indicates recent pollution by municipal sewage. Survival of these bacteria in the sea water depends on the complex of biological, chemi-cal and physical water parameters. There are many conflicting opinions on bacterial death-rate and the data on this phenomenon for the Gulf of Gdansk are rather scarce. The influence of irradi-ance (0-200 mumol photon m-2 s-1), temperature (5-20 ?C) and salinity (0-7.5 psu) on the survival of Escherichia coli strain K-12 has been investigated. The bacterial cultures were incubated for three days under chosen temperature, salinity and irradiance conditions. Experiments were planned based on the factorial design (method x'). The cell density was determined every day by direct viable count on agar plates. The obtained results were analysed statistically in such a way that temperature, salinity and irradiance were independent variables whereas Escherichia coli number and mean mortality coefficient (Km) were the dependent ones. It was found that the effect of salinity (in studied range from 0 to 7.5 psu) on Escherichia coli survival was not statistically significant. However, the survival was strongly correlated with temperature and irradiance. Correlation coefficient (R) between temperature and irradiance and mean coefficient of Escherichia coli mortality (Km) equalled 0.801. This dependence can be described by a function, obtained from nonlinear regression analysis, Km = 6.466 - 0.195 t + 2.215?10-7 t2 i2. The function will be used for the development of a model of matter circulation and energy flow in the Gulf of Gdansk.
4

Streptomyces and Escherichia coli, model organisms for the analysis of the initiation of bacterial chromosome replication

100%
Messer W., Zakrzewska-Czerwinska J.
Archivum Immunologiae et Therapiae Experimentalis
|
2002
|
vol. 50
|
issue 6
391-396
EN
Streptomyces coelicolor A3(2) and Escherichia coli are quite different in their life-style and the structures of their genomes. Streptomyces exhibit complex multicellular development including formation of multigenomic hyphae during growth. These organisms possess a large linear (8.7 Mb) and GC-rich (~72%) chromosome. The genome sequence of S. coelicolor has just been completed. The difference between E. coli and Streptomyces making them an excellent model organisms for a comparison of their replication modes. In this review, we compare initiation of chromosome replication in both organisms. Their replication origins are different in size, but both have DnaA boxes ? a binding motifs for initiator DnaA protein. The two DnaA proteins have practically the same biochemical properties. Many aspects of the control of initiation seem to be similar. A comparison of the two systems thus allows us to define those aspects of replication initiation that are universally used in the eubacterial kingdom.
5

Methods for isolation, purification and renaturation of recombinant proteins obtained in Escherichia coli bacteria

88%
Szczepanek A., Plucienniczak A.
Biotechnologia
|
1994
|
issue 4
102-125
EN
Escherichia coli is the most useful bacterial species applied to genetic engineering in recombinant proteins production process.The supply of many polipeptides with potential clinical or industrial use is often limited by their low natural availability. Overexpressed polipeptides may either be located in the cytoplasm and periplasm of E.coli or secreted through the cell membrne into the growth medium.Foreign proteins can be expressed in E.coli cells directly or as fusion proteins with prokaryotic sequences. Frequently, the overexpressed proteins acumulate in the bacterial cytoplasm or periplasm in the form of insoluble inclusion bodies.This review considers isolation, purification, solubiliztion and renaturation of recombinant proteins from E.coli, which is still a serious methodological and technical renaturtion.
6

Inclusion bodies and their application for the production of recombinant proteins in Escherichia coli expression system

88%
Sierant M., Okruszek A.
Biotechnologia
|
2004
|
issue 1
9-19
EN
Over-expression of recombinant proteins in Escherichia coli, the most frequently used prokaryotic expression system, often results in the formation of intracellulary aggregated, insoluble folding intermediates. It is generally thought that protein aggregation is triggered by the failure of polypeptide intermediates to complete folding, leading to self-association. These aggregates are known as inclusion bodies or refractile bodies, since they appear upon microscopic observation as highly refractile areas. The formation of inclusion bodies often increases the yields of recombinant proteins and falicitates their isolation. The aggregated proteins are usually protected from proteases and do not harm host cells. Specific strategies are developed to produce bio-active proteins with the participation of inclusion bodies. These procedures include: 1) isolation and purification of inclusion bodies, 2) solubilization of the protein aggregates, and 3) renaturation of solubilized proteins involving formation of native disulphide bonds.
7

Abnormalities in the handling of intracellular bacteria in Crohn's disease: a link between infectious etiology and host genetic susceptibility

88%
Glasser A.-L., Darfeuille-Michaud A.
Archivum Immunologiae et Therapiae Experimentalis
|
2008
|
vol. 56
|
issue 4
237-244
EN
The etiology of Crohn's disease (CD) is still poorly understood, but recent advances have highlighted the importance of the innate immune system and the critical relationship between the gut flora and the intestinal mucosa. Several combinations of genetic factors predisposing to CD have been described, with the most significant replicable associations including genes for intracellular receptors of bacterial cell walls (NOD2/CARD15) and for bacterial clearance and antigen processing via autophagy (ATG16L1 and IRGM). One theoretical link between susceptibility genes NOD2/CARD15, ATG16L1, and IRGM is that CD is primarily induced by the presence of a dysfunctional immunological response to persistent infection by intracellular bacterial pathogens such as Mycobacterium avium subspecies paratuberculosis or adherent-invasive Escherichia coli, both first-rank candidates on the basis of host genetic susceptibility, which concerns impaired functions in the defense against intracellular bacteria.
8

Lactoferrin stimulates killing and clearance of bacteria but does not prevent mortality of diabetic mice

88%
Zagulski T., Jarzabek Z., Zagulska A., Jaszczak M., Kochanowska I. E., Zimecki M.
Archivum Immunologiae et Therapiae Experimentalis
|
2001
|
vol. 49
|
issue 6
431-438
EN
We have previously shown that bovine lactoferrin (BLF) given intravenously (i.v.) protected mice against a lethal dose of E. coli and strongly stimulated both the clearing and killing activities in liver, lungs, spleen and kidney. Since some studies indicated a reduction of the manifestation of experimental pancreatitis with lactoferrin, we decided to examine the protective activity of BLF against lethal E. coli infection in animals with alloxan (Alx)-induced diabetes. It appeared that 48 h diabetes substantially lowered the killing activity in all four organs as well as the clearing rate of E. coli from the circulation. BLF given i.v. o reduced this undesirable effect of diabetes. However, in 10- and 20-day diabetic animals, the diabetes alone stimulated the killing activity in the organs investigated, and upregulated the clearing rate of E. coli from the circulation. Lactoferrin (LF) significantly increased both the killing and the clearing activity in these long-term diabetic animals. In some cases the stimulating effect of BLF was very high, suggesting a concerted action of BLF and diabetes in that category of mice. Despite these beneficial effects of BLF and diabetes on the killing process in the investigated organs, the survival time of animals from all the diabetic groups ( 48 h, 10 and 20 days) was not prolonged by BLF. The protective properties of BLF did not depend on the blood glucose levels in the diabetic animals. BLF partly delayed the development of experimental Alx-induced diabetes, measured by the glucose level, but only if administered shortly after Alx injection. In conclusion, we demonstrated that the state of diabetes alone could increase killing of bacteria in the investigated organs and LF enhanced this process. However, LF had no protective effect against the mortality of diabetic mice infected with a lethal dose of E. coli.
9

The minimal genome paradox

88%
Wegrzyn G.
Journal of Applied Genetics
|
2001
|
vol. 42
|
issue 3
385-392
EN
The concept of a ?minimal genome? has appeared as an attempt to answer the question what the minimum number of genes or minimum amount of DNA to support life is. Since bacteria are cells bearing the smallest genomes, it has been generally accepted that the minimal genome must belong to a bacterial species. Currently the most popular chromosome in studies on a minimal genome belongs to Mycoplasma genitalium, a parasite bacterium whose total genetic material is as small as 580 kb. However, the problem is how we define life, and thus also a minimal genome. M. genitalium is a parasite and requires substances provided by its host. Therefore, if a genome of a parasite can be considered as a minimal genome, why not to consider genomes of bacteriophages? Going further, bacterial plasmids could be considered as minimal genomes. The smallest known DNA region playing the function of the origin of replication, which is sufficient for plasmid survival in natural habitats, is as short as 32 base pairs. However, such a small DNA molecule could not form a circular form and be replicated by cellular enzymes. These facts may lead to an ostensibly paradoxical conclusion that the size of a minimal genome is restricted by the physical size of a DNA molecule able to replicate rather, than by the amount of genetic information.
10

Characteristics of the ability to uptake cadmium by bacteria biosorbents

75%
Wojnowska-Baryla I., Stolarczyk E., Gredzinska A.
Biotechnologia
|
1997
|
issue 4
113-124
EN
The ability of the following bacteria: Escherichia coli, Kliebsiella pneumoniae, Proteus mirabilis, Proteus vulgaris, Pseudomonas sp. to uptake cadmium from water solution was investigated. Based on the parameters of Freundlich and Langmuir equations it was found that the kind of equation describing cadmium uptake by bacteria cells depended on the range of initial cadmium concentration in solution. Cadmium uptake by the investigated strains of bacteria from solution with low initial concentration of cadmium proceeded according to the Freundlich model. Increasing of the initial cadmium concentration above 30 mg Cd2+? dm-3 resulted in a change of the cadmium uptake mechanism and sorption was according to the Langmuir model. The best biosorbents were Pseudomonas sp. and Proteus vulgaris which showed high sorption ability in a wide range of initial concentrations (1-200 mg Cd2+ ? dm-3). In the range of low initial cadmium concentration (1-30 mg Cd2+? dm-3), the most effective biosorbent was Kliebsiella pneumoniae.
11

Asymmetry of nucleotide composition of prokaryotic chromosomes

75%
Mackiewicz P., Gierlik A., Kowalczuk M., Dudek M., Cebrat S.
Journal of Applied Genetics
|
1999
|
vol. 40
|
issue 1
1-14
EN
We have analysed the causes of asymmetry in nucleotide composition of DNA complementary strands of prokaryotic chromosomes. Analysing DNA walks we have separated the effect of replication-associated processes from the effect introduced by transcription and coding functions. The asymmetry introduced by replication switches its polarity at the origin and at the terminus of replication, which is observed in both noncoding and coding sequences and varies with respect to positions in codons. Coding functions introduce very strong trends into protein coding ORFs, which are specific for each nucleotide position in the codon. Using detrended DNA walks we have eliminated the effect of coding density and we were able to distinguish between mutational pressure associated with replication and compositional bias for genes proximal and distal to the origin of replication.
12

Heterologous genes expression in E. coli; interferon gamma as the model system

75%
Cieslikowski T.
Biotechnologia
|
1997
|
issue 2
71-92
EN
Interferon gamma is a molecule which may serve as a good object for studying and explaining the role of expression limiting conditions. Three levels of limiting factors modifications, i. e. operon choice and structure, changes in the secondary mRNA structure, and the influence of post-translational modulation processes are described. The relationship between the operon stucture and expression level for other heterologous proteins is compared with that of IFN-gamma. In particular, the shape of ribosome binding site (RBS) region and its affected different nucleotide substitutions are presented. The rule of N-terminal and C-terminal end changes for protein stability and inclusion body formation is also shown.
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