All posts by Postępy Mikrobiologii

Bakteriocyny bakterii Gram-ujemnych – struktura, mechanizm działania i zastosowanie

Bacteriocins of Gram-negative bacteria – structure, mode of action and potential applications
U. Błaszczyk, J. Moczarny
2 July 2017

1. Wprowadzenie. 2. Klasyfikacja bakteriocyn bakterii Gram-ujemnych. 3. Produkcja kolicyn przez bakterie kolicynogenne. 3.1. Synteza kolicyn. 3.2. Eksport kolicyn z komórek producenta. 4. Mechanizmy działania kolicyn. 4.1. Translokacja. 4.2. Efekt letalny kolicyn. 5. Charakterystyka i podział mikrocyn. 5.1. Struktura i genetyka wybranych mikrocyn. 5.1.1. MccE492. 5.1.2. MccJ25. 5.1.3. MccC7-C51. 5.2. Mechanizmy działania mikrocyn. 5.2.1. MccE492. 5.2.2. MccJ25. 5.2.3. MccC7-C51. 6. Potencjalne zastosowanie kolicyn i mikrocyn. 7. Podsumowanie

Abstract: Bacteriocins are a diverse group of ribosomally synthesized peptides or proteins secreted by bacteria, which help them to compete in their local environments for the limited nutritional resources. Bacteriocins kill or inhibit the growth of other bacteria. Generally, these molecules have a narrow spectrum of antibacterial activity, but some of them demonstrate a broad spectrum of action. Bacteriocins from Gram-negative bacteria are divided into two main groups: high molecular mass proteins (30–80 kDa) known as colicins, and low molecular mass peptides (between 1–10 kDa) termed microcins. Colicins are produced by Escherichia coli strains harbouring a colicinogenic plasmid. Such colicinogenic strains are widespread in nature and are especially abundant in the gut of animals. The biosynthesis of colicins is mediated by the SOS regulon, which becomes activated in the response to DNA damage. The colicin synthesis is lethal for the producing cells as a consequence of the concomitant biosynthesis of the colicin lysis protein. Microcins are usually highly stable molecules, which are resistant to proteases, extreme pH values and temperatures. They are produced by enteric bacteria under stress conditions, particularly nutrient depletion. Microcins are encoded by gene clusters carried by plasmids or in certain cases by the chromosome. In this review, we have summarized the most important information about structure and properties of bacteriocins from Gram-negative bacteria, their diverse mechanisms of action and potential application as food preservatives and in livestock industry.

1. Introduction. 2. Classification of bacteriocins from Gram-negative bacteria. 3. Production of colicins by colicinogenic bacteria. 3.1. Colicin synthesis. 3.2.  Export of colicins from bacteriocin-producing cells. 4. Modes of colicin action. 4.1. Translocation. 4.2. Lethal effect of colicins. 5. Characteristics and classification of microcins. 5.1. Structure and genetics of selected microcins. 5.1.1. MccE492. 5.1.2. MccJ25. 5.1.3. MccC7-C51. 5.2. Mechanisms of action of microcins. 5.2.1. MccE492. 5.2.2. MccJ25. 5.2.3. MccC7-C51. 6. Potential applications of colicins and microcins. 7. Summary

Autor: Postępy Mikrobiologii
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Skuteczność wykorzystania niskotemperaturowej plazmy w mikrobiologii i medycynie

Efficiency of using non-thermal plasma in microbiology and medicine
M. Laskowska, E. Bogusławska-Wąs, P. Kowal, M. Hołub, W. Dąbrowski
2 July 2017

1. Wstęp. 2. Mechanizm działania zimnej plazmy na mikroorganizmy. 2.1. Efektywność działania sterylizującego. 3. Zastosowanie zimnej plazmy w medycynie. 4. Podsumowanie

Abstract: Plasma is a partially or totally ionized gas which occurs in nature (e.g. lightning discharge, outer space), but can be also created in the laboratory conditions. Non-thermal plasma generates free radicals of oxygen, nitrogen, high energy electrons and uncharged particles such as atoms and molecules, in aquatic and gas environment. Thus, plasma exerts its effect on both prokaryotic and eukaryotic cells. In many studies, non-thermal plasma was applied mainly to achieve the sterilization effects of e.g. surfaces and medical tools. The results obtained were largely dependent upon the applied parameters of plasma (e.g. frequency, voltage, type of gas). Non-thermal plasma can be applied in microbiology and also in medicine where it can be used to speed up wound healing process or as an effective tool in oncology.

1. Introduction. 2. Plasma action on microorganisms. 2.1. Sterilization efficiency. 3. Application of cold plasma in medicine. 4. Summary

Autor: Postępy Mikrobiologii
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Drobnoustroje radiotolerancyjne – charakterystyka wybranych gatunków oraz ich potencjalne zastosowanie

Radiotolerant microorganisms – characterization of selected species and their potential usage
D. M. Matusiak
2 July 2017

1. Wprowadzenie. 1.1. Promieniowanie oraz jego wpływ na organizmy żywe. 1.2. Drobnoustroje radiotolerancyjne – definicja, teorie na temat pochodzenia, oporność na promieniowanie. 2. Charakterystyka wybranych organizmów radiotolerancyjnych. 2.1. Bakterie. 2.2. Archeony. 2.3. Grzyby mikroskopowe. 3. Podsumowanie

Abstract: Ionizing radiation damages DNA, proteins and lipids in cells in a direct (10–20% DNA damage) and indirect manner (80–90%) – causing water radiolysis and a redox potential increase (oxido-reductive stress). For instance, hydrogen peroxide and ozone are generated. Hydroxyl radical (OH.) is the most reactive and harmful reactive oxygen species (ROS). Radiotolerant microorganisms are extremophilic microbiota, sustaining high doses of radiation in a vegetative state. One of the most resistant and extensively studied species is Deinococcus radiodurans. This bacterium can reconstitute its genome shattered to dozens of fragments (double strand breaks) as a result of the exposure to radiation or dessication. Other examples include: bacteria: Acinetobacter radioresistens, Rubrobacter radiotolerans, Kineococcus radiotolerans, Ralstonia sp. and Burkholderia sp. (living in biofilm communities from spent fuel pools); archaea: Thermococcus gammatolerans; diverse microscopic, often melanized, presumably radiotropic fungi, e.g. Cladosporium spp., from the surrounding of the destroyed Chernobyl power plant. Many of such organisms can be found in desert areas as they are dehydratation-tolerant. Radioresistant species can be potentially utilized for bioremediation of radioactive environment contamination and for nuclear waste management (e.g. bioprecipitation, biosorption, bioaccumulation of uranium or other radioisotopes). For example, diverse molds isolated from the Chernobyl region can be used for mycoremediation due to their ability to decompose contaminated organic matter, adsorb, converse into a soluble form and accumulate radionuclides (e.g. caesium 137).

1. Introduction. 1.1. Radiation and its effect on organisms. 1.2. Radiotolerant microorganism – definition, theories about their origin, radioresistance. 2. Description of selected radiotolerant species 2.1. Bacteria. 2.2. Archaea. 2.3. Microfungi. 3. Summary

Autor: Postępy Mikrobiologii
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Wpływ stresu kwasowego i osmotycznego na wytwarzanie metabolitów przy użyciu mikroorganizmów

The efect of acid and osmotic stress onmetabolite production by microorganisms
J. Fiedurek, M. Trytek
2 July 2017

1. Wstęp. 2. Stresy abiotyczne. 2.1. Stres kwasowy. 2.2. Stres osmotyczny. 3. Podsumowanie

Abstract: The efficiency of the overall biotechnological processes is strongly dependent on the interaction between the microbial biocatalyst and the stressful environment. Microorganisms have evolved to survive constant fluctuation in their external surroundings by special adaptation systems, including the reorganization of genomic expression by activation of transcriptional factors under stress conditions and the production of suitable metabolites. There is some evidence that more active microbial cells may be obtained by using abiotic stresses, such as osmotic and acidic stress, before or during the process. Also, changes in the conditions of stress application, for example its duration or simultaneous increase in temperature, may improve the yield, probably as a result of changes in the metabolic pathway of the microorganisms used. In this review, we have summarized the most important information from available literature on the effect
of acid and osmotic stress on the production of useful metabolites by microorganisms.

1. Introduction. 2. Abiotic stresses. 2.1. Acidic stress. 2.2. Osmotic stress. 3. Conclusions

Autor: Postępy Mikrobiologii
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Filowirusy – wirusy obecne od milionów lat – dlaczego teraz wybuchła tak wielka epidemia?

Filoviruses – viruses existing for millions of years – why do we have such a big outbreak now?
K. Pancer, W. Gut, B. Litwińska
2 July 2017

1. Rys historyczny i charakterystyka. 2. Struktura i zmienność EBOV. 3. Rezerwuar zwierzęcy filowirusów. 4. Podstawowe etapy cyklu życiowego wirusa Ebola w komórce. 5. Wybrane mechanizmy patogenności wirusa Ebola. 6. Paleowirusologia. 7. Podsumowanie

Abstract: Ebola virus, discovered in 1976, caused the largest epidemic among humans in 2014. In this paper, we have discussed the systematic position of Ebolavirus, the ecology of these viruses, the essential elements of pathogenesis of infections as well as comparative characteristics of Filoviruses infectious biology. According to the paleovirological data, these features were developed during millions of years of the co-evolution process and co-existence of pathogens and hosts. It is likely that changes of Ebola virus biology are not the reason for such substantial changes in the epidemiology of Ebola virus infections. Analysis of factors associated with the characteristics of the present epidemic (size, region) indicate that the main reason for such big epidemic may be the changes related to both humans activity, mainly transformation of the environment, and the ability of bats (natural hosts of Filoviruses) to adapt to the new ecological conditions. These processes may cause more outbreaks in the future, also on a large scale, and require taking appropriate actions to reduce the risks.

1. History and characteristics of filoviruses. 2. The structure and variability of EBOV. 3. Animal reservoir of Filoviruses. 4. Basics of the Ebola virus life cycle in the cell. 5. Selected mechanisms of pathogenicity of Ebola virus. 6. Filovirus paleovirology. 7. Summary

Autor: Postępy Mikrobiologii
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Advancements of Microbiology
Volume 63 (2024): Issue 3

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PTM

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