All posts by Postępy Mikrobiologii

Biofilm, pompy MDR i inne mechanizmy oporności Stenotrophomonas maltophilia na związki przeciwbakteryjne

Biofilm, MDR efflux pumps and other mechanisms of Stenotrophomonas maltophilia resistance to antibacterial substances
O. Zając, A. E. Laudy, S. Tyski

1. Wstęp. 2. Leczenie zakażeń S. maltophilia. 3. Oporność na związki przeciwbakteryjne. 3.1. Oporność na antybiotyki i chemioterapeutyki. 3.2. Oporność na środki dezynfekcyjne. 3.3. Oporność na jony metali. 4. Systemy pomp. 4.1. Rodzina RND. 4.2. Rodzina MFS. 4.3. Rodzina ABC. 4.4. Pompa FuaABC. 5. Biofilm bakteryjny i system quorum sensing. 6. Podsumowanie

Abstract: Stenotrophomonas maltophilia is a non-fermentative Gram-negative rod, which can cause many infections, including pneumonia and bacteremia, especially in immunocompromised or long-term hospitalized patients. The infections are difficult in therapy, because clinical isolates are usually highly resistant to many classes of antimicrobial agents, moreover, they are able to colonize medical devices and epithelial cells and form biofilm. The several resistance mechanisms of S. maltophilia to antibacterial agents have been described, among them: β-lactamases production, production of other enzymes modifying antibiotics structure and activity of multidrug efflux pumps (MDR). Up to date, eight MDR efflux pumps have been identified in S. maltophilia strains. These pumps belong to three different families of MDR pumps and RND family plays the most important role in multidrug resistance.

1. Introduction. 2. Treatment of S. maltophilia infections. 3. Resistance to antibacterial substances. 3.1. Resistance to antibiotics and chemotherapeutics. 3.2. Resistance to disinfectants. 3.3. Resistance to metals. 4. Efflux systems. 4.1. RND family. 4.2. MFS family. 4.3. ABC family. 4.4. The FuaABC efflux pump. 5. Biofilm and quorum sensing system. 6. Summary

Rola mitochondriów w odporności przeciwwirusowej

The role of mitochondria in antiviral immunity
K. P. Gregorczyk, Z. Wyżewski, L. Szulc-Dąbrowska, J. Struzik, J. Szczepanowska, M. Niemiałtowski

1. Wstęp. 2. Udział mitochondriów w produkcji IFN typu I oraz cytokin prozapalnych. 3. Wirusowe mechanizmy hamowania zależnej od mitochondriów produkcji IFN typu I oraz cytokin prozapalnych. 4. Apoptoza – proces „pseudoprzeciwwirusowy”. 5. Podsumowanie

Abstract: Mitochondria, which are known as “powerhouse” of the cell, have numerous important functions in cellular metabolism and are involved in cellular innate antiviral immunity in vertebrates. They participate in an intrinsic pathway of apoptosis and production of proinflammatory cytokines and type I interferons (IFNs; α/β). These functions are essential for limiting the spread of viral infection before the stimulation of adaptive immunity. However, viruses have evolved the ability to escape from the mechanisms of immune response including those related to mitochondrial functions. Viruses can exploit these organelles in their replication cycle and/or morphogenesis process, therefore the answer to the question about the exact role of mitochondria during viral infection is not unequivocal.

1. Introduction. 2. Contribution of mitochondria in type I IFN and pro-inflammatory cytokines production. 3. Viral inhibition mechanisms of the mitochondrial-dependent production of type I IFN and pro-inflammatory cytokines. 4. Apoptosis – “pseudoantiviral” process. 5. Summary

Kultury starterowe do produkcji twarogów kwasowych – rola i oczekiwania

Starter cultures for acid curd – role and expectations
J. Żylińska, K. Siemianowski, K. Bohdziewicz, K. Pawlikowska, P. Kołakowski, J. Szpendowski, J. Bardowski

1. Wstęp. 2. Technologia twarogów kwasowych. 3. Rola kultur starterowych w produkcji serów twarogowych. 4. Kultury starterowe w produkcji twarogu kwasowego. 4.1. Oporność na bakteriofagi. 4.2. Produkcja bakteriocyn. 4.3. Aktywność proteolityczna i lipolityczna. 4.4. Produkcja zewnątrzkomórkowych polisacharydów. 5. Podsumowanie

Abstract: Lactic acid bacteria are industrially important microbes used all over the world in a large variety of industrial food fermentations. Cheese, cottage cheese, especially acid curd cheese, are characteristic dairy products for some Central and Eastern European countries. For production of acid curd cheese, only two components are needed: milk and lactic acid bacteria starter cultures. Starter cultures determine in large extent the technological process, the quality of the resulting quark and its shelf life. The composition of quark acid bacteria cultures is constituted in majority by Lactococcus and Leuconostoc bacteria. Selection of strains and construction of cultures with balanced species and stable composition for acid curd production is still very complex and presents a difficult challenge for producers of dairy cultures.

1. Introduction. 2. Acid curd technology. 3. The role of starter cultures in the production of cottage cheese. 4. Starter cultures for acid curd. 4.1. Bacteriophage resistance. 4.2. Bacteriocin production 4.3. Proteolytic and lipolytic activity. 4.4. Production of extracellular polysaccharides. 5. Summary

Rola alternatywnych czynników sigma S (σS) i sigma B (σB) w odpowiedzi komórki bakteryjnej na stres oraz ich regulacja

The role of alternative sigma factor S (σS) and sigma factor B (σB) in bacterial cell stress response and their regulation
M. Opęchowska, S. Bielecki

1. Wstęp. 2. Alternatywny czynnik sigma B (σB). 2.1. Regulacja σB u Bacillus subtilis. 2.2. Regulacja σB u Bacillus cereus. 2.3. Geny zależne od σB. 3. Alternatywny czynnik sigma S (σS/rpoS). 3.1. Regulacja transkrypcji rpoS. 3.1.1. Czynniki kontrolujące transkrypcję rpoS. 3.1.1.1. cAMP-CRP i EIIA (Glc). 3.1.1.2. Wpływ ppGpp na transkrypcję rpoS. 3.2. Regulacja translacji rpoS. 3.2.1. Funkcje regulatorowych RNA w translacji rpoS. 3.2.2. Wpływ UDP-glukozy na translację rpoS. 3.3. Regulacja proteolizy σS. 3.3.1. Degradacja σS przez kompleks proteazy ClpXP zależnej od ATP. 4. Podsumowanie

Abstract: Bacteria successfully take possession of almost every recess of the earth. However bacteria can be liable to big changes of environmental conditions in every settled biotope. Some of them living in a high specializated medium do not show usually ability of tolerate others media than their most favourable. In case of changes of medium parameters some of bacteria start to migrate and look for others media securing them proper growth and development approximate optimum conditions. There are also bacteria which are able to survive in spite of changes happen in their direct environmental. Their survival competence is caused by the lack of susceptibility on specified medium changes or ability of adaptation to new conditions moreover by taking the profits from the medium. The tolerance and adaptation bacterial cells to different conditions which following in the nearest environmental result from cells response on stress factors. Precised signals coming from the medium cause in the cells a number of changes happen in genes expression regulated on transcription and translation level. The information coded in bacterial genome enable cells to produce many different proteins. However not all proteins are synthesized in the same time and the process of their synthesis is subject to strict control. Cells under stress synthesize proteins which secure them survival in untipical for their growing conditions. The main roles in this process play alternative sigma factors. Bacterial cells contain also general sigma factor (for example σ70 in Escherichia coli, σ43 in Bacillus subtilis) responsible for transcription most of the genes. However alternative sigma factors rarely regulate initiation of transcription. They are active only in case of cell stress conditions and also they take part in gene expression conected with the life cycle of the cell and stationary or exponential growth phase of bacteria. The most important function in stress conditions of E. coli plays an alternative sigma S (σS, σ38) factor. Because of its regulatory function a lot of attention is dedicated to researches refer to σS in a recent time. Sigma B – which is one of the best known alternative sigma factors in Gram-positive bacteria – plays a similar role to sigma S. Factor σB functions as a general response regulator to stress in such bacteria as Bacillus, Staphylococcus and Listeria. These two alternative sigma factors: sigma S and sigma B often, if not always work in connection with others form of regulation. Bacteria show ability of detection many signals coming from the environment by means of sensors systems situated in cell envelope. Although σS and σB play the similar role in the cell they are controlled by completely different mechanisms.

1. Introduction. 2. Alternative sigma factor B (σB). 2.1. Regulation of σB in Bacillus subtilis. 2.2. Regulation of σB in Bacillus cereus. 2.3. σB – dependent genes. 3. Alternative sigma factor S (σS/rpoS). 3.1. Regulation of rpoS transcription. 3.1.1. Factors controlling rpoS transcription. 3.1.1.1. cAMP-CRP i EIIA (Glc). 3.1.1.2. The influence of ppGpp on rpoS transcription. 3.2. Regulation of rpoS translation. 3.2.1. The functions of regulatory RNAs in rpoS translation. 3.2.2. The influence of UDP-glucose on rpoS translation. 3.3. Regulation of σS proteolysis. 3.3.1. Degradation of σS by the ClpXP ATP-dependent protease complex. 4. Conclusion

Proces biogenezy cytochromów c w komórkach bakteryjnych – rola białek Dsb (disulfide bond)

Cytochrome c biogenesis in prokaryotic cells – the role of Dsb proteins
P. Roszczenko, M. Grzeszczuk, E. K. Jagusztyn-Krynicka

1. Białka Dsb (disulfide bond). 2. Różnorodność procesu biogenezy cytochromów c w komórkach bakteryjnych. 2.1. Transport i redukcja apocytochromu. 2.2. Transport i przyłączanie hemu do zredukowanego apocytochromu. 3. Podsumowanie

Abstract: The bacterial proteins of the Dsb family catalyze the formation of disulfide bridges, a post-translational modification of many extracytoplasmic proteins, leading to stabilization of their tertiary and quaternary structures. In Gram-negative bacteria this process takes place in the periplasm whereas in Gram-positive bacteria it occurs in the analogous space between the cytoplasmic membrane and the cell wall. In E. coli (Ec) the Dsb system operates in two partially coinciding metabolic pathways: the oxidation (DsbA and DsbB) and the isomerization/reduction (DsbC and DsbD). In the highly oxidizing environment of the periplasm, there is also a need for selected proteins to be kept in a reduced form. Assembly of c-type cytochromes, essential for energy metabolism, is a case of point. Two distinct different systems for cytochrome-c maturation was found in bacteria: system I known as Ccm (cytochrome c maturation) and system II known as Ccs system (cytochrome c synthesis). They comprise two kind of proteins: those contributing to transport and reduction of disulfide bond of CXXCH of apocytochrome c and those involved in handling of heme and playing a role in its ligation to the apocytochrome. The cytochrome c maturation process requires ligation of heme to reduced thiols of the Cys-X-X-Cys-His motif of the apocytochrome. Since DsbA, the main periplasmic dithiol-oxidase randomly introduces disulfide bonds into apocytochromes, bacterial evolved a special redox system to revert these disulfides, in highly oxidizing environment, into reduced cysteine residues. Thiol-oxidoreductases, CcmG proteins, previously designated as DsbE, play a key role in this process. Here we discuss the variety of two cytochrome c biogenesis systems and discuss some of the current problems in understanding how the process works putting special emphasis on the recent achievements concerning the process driving by CcmGs.

1. Dsb proteins. 2. Diversity of cytochrome c biogenesis. 2.1 Transport and reduction of apocytochrome c. 2.2 Heme translocation and ligation into reduced apocytochrome. 3. Conclusions

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POSTĘPY MIKROBIOLOGII
2019, 58, 1

O Towarzystwie

PTM

Celem Polskiego Towarzystwa
Mikrobiologów jest propagowanie rozwoju nauk mikrobiologicznych

i popularyzowanie osiągnięć
mikrobiologii wśród członków Towarzystwa oraz szerokich kręgów społeczeństwa. Formami działalności jest organizowanie zjazdów, posiedzeń naukowych, kursów, wykładów
i odczytów oraz konkursów prac naukowych; wydawanie i popieranie wydawania czasopism naukowych, książek
i innych publikacji
z dziedziny mikrobiologii; opiniowanie o stanie i potrzebach mikrobiologii polskiej

i występowanie w jej sprawach wobec
władz państwowych; współpraca
z pokrewnymi stowarzyszeniami
w kraju i za granicą.