All posts by Postępy Mikrobiologii

TAKSONOMIA, WIRULENCJA I CYKLE ŻYCIOWE BACILLUS CEREUS SENSU LATO

Taxonomy, virulence and life cycles of Bacillus cereus sensu lato
Marek Bartoszewicz, Urszula Czyżewska
8 December 2017

1. Wstęp. 2. Najważniejsze aspekty biologii B. cereus sensu lato. 2.1. Wyzwanie pierwsze – spójna taksonomia. 2.2. Wyzwanie drugie – cykle życiowe i interakcje z otoczeniem. 2.3. Wyzwanie trzecie – adaptacja do niskich temperatur. 2.4. Wyzwanie czwarte – toksyny B. cereus sensu lato. 3. Podsumowanie

Abstract: Bacillus cereus sensu lato is a group of several species of Gram-positive sporeformers ubiquitous in nature and showing huge impact on human activities. They are often found in soil, air, plant material, animal tissues and digestive tracts as well as in food products. Their genetic similarities and frequent horizontal gene transfer causes doubts regarding their taxonomy. In addition, their toxicity and psychrotolerance constitute serious problems in the dairy industry, being responsible for food-poisonings and spoilage of cold-stored products. Finally, recent finding indicate that B. cereus sensu lato toxicity plays an important role not only in their virulence, but also in social interactions with other bacteria.

1. Introduction. 2. The most important aspects of B. cereus sensu lato biology. 2.1. First challenge – coherent taxonomy. 2.2. Second challenge – life cycles and interactions with the environment. 2.3. Third challenge – adaptation to low temperatures. 2.4. Fourth challenge – toxins of B. cereus sensu lato. 3. Summary

Autor: Postępy Mikrobiologii
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CHARAKTERYSTYKA I POTENCJALNE ZASTOSOWANIE BAKTERIOCYN CYKLICZNYCH

Characteristics and potential applications of circular bacteriocins
Urszula Błaszczyk, Kamila Dąbrowska
8 December 2017

1. Charakterystyka i klasyfikacja bakteriocyn cyklicznych. 2. Genetyka bakteriocyn cyklicznych. 3. Biosynteza bakteriocyn cyklicznych. 4. Struktura bakteriocyn cyklicznych. 5. Mechanizmy działania bakteriocyn cyklicznych. 6. Enterocyna AS-48. 7. Potencjalne zastosowanie bakteriocyn cyklicznych. 8. Podsumowanie

Abstract: Bacteriocins are ribosomally synthesized peptides or proteins exerting anatagonistic activity toward organisms which are closely related to the producer strain. Circular bacteriocins are produced by Gram-positive bacteria, mainly lactic acid bacteria, and to a lesser extent by Bacillus, Clostridium and Staphylococcus genera. These bacteriocins are characterized by the head-to-tail cyclization of their backbone. The circular nature of these peptides makes them resistant to many proteolytic enzymes and provides great thermal and pH stability. Circular bacteriocins are divided into 2 subgroups based on their physicochemical properties and sequence identity. These bacteriocins are synthesized as linear precursors with a leader sequence which is cleaved off during maturation. The mature circular peptides are composed of 58–70 amino acid residues. Biosynthesis of circular bacteriocins requires three stages: cleavage of the leader sequence, circularization and export out of the cell. Circular bacteriocins have broad antimicrobial activity spectrum, including many food spoilage bacteria and pathogens, such as Listeria, Staphylococcus and Clostridum spp. Circular bacteriocins permeabilize the membrane of sensitive bacteria, causing loss of ions and dissipation of the membrane potential, and finally cell death. Enterocin AS-48 was the first identified circular bacteriocin and is best characterized so far. Circular bacteriocins or bacteriocin-producing lactic acid bacteria have great potential in food preservation, and possibly in pharmaceutical and cosmetic industries. Thanks to their properties, circular bacteriocins could be an alternative not only to preservatives and methods used to provide microbial food safety presently, but also to less stable, linear bacteriocins.

1. Characteristics and classification of circular bacteriocins. 2. Genetics of circular bacteriocins. 3. Biosynthesis of circular bacteriocins. 4. Structure of circular bacteriocins. 5. Modes of action of circular bacteriocins. 6. Enterocin AS-48. 7. Potential applications of circular bacteriocins. 8. Summary

Autor: Postępy Mikrobiologii
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ZMIANY W TAKSONOMII γ-PROTEOBACTERIA, MODYFIKACJA NAZWY RZĘDU ENTEROBACTERIALES I NOWE RODZINY W OBRĘBIE ENTEROBACTERALES ORD. NOV.

Changes in the taxonomy of γ-Proteobacteria, modification of the order Enterobacteriales and novel families within Enterobacteriales ord. nov.
Paweł Nawrotek, Bartłomiej Grygorcewicz, Adrian Augustyniak
8 December 2017

1. Wstęp. 2. Zasady dotyczące wprowadzania zmian taksonomicznych. 3. Przesłanki wprowadzania zmian taksonomicznych. 4. Zmiany w rzędzie Enterobacterales ord. nov. 5. Bazy danych a zmiany w taksonomii rzędu Enterobacterales ord. nov. 6. Podsumowanie

Abstract: Prokaryotic diversity increases every year with each new described species. Since the first discoveries of microorganisms, researchers’ endeavours are dedicated to the systematisation of all known living organisms in a consistent taxonomy. Originally based on morphology, in recent years modern taxonomy develops thanks to the implemenation of new discoveries in the fields of biochemistry and genetics. In the last thirty years, ribotyping was the leading technique used to classify microorganisms. Due to problems with the comparison of certain species, novel methods based on the analysis of proteins have been applied. In-depth analysis of Enterobacteriaceae family showed that its members are more dissimilar than previously thought, which eventually led to dividing this family into seven families and resulted in a change to the name of the order: from Enterobacteriales to Enterobacterales. These changes were applied in some biggest accessible databases. However, there are still many other which have not modified their taxonomy records to date. Such situation may lead to unnecessary confusion, which strengthens the necessity to create one, unified taxonomy which is approved by the whole scientific community.

1. Introduction. 2. Principles regarding the introduction of taxonomical changes. 3. Justification of taxonomical changes. 4. Modifications in the order Enterobacterales ord. nov. 5. Databases and changes in the taxonomy of the order Enterobacterales ord. nov. 6. Summary

Autor: Postępy Mikrobiologii
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Molekularne podłoże oddziaływań pomiędzy Borrelia burgdorferi, kleszczem i kręgowcem

Molecular interactions between Borrelia burgdorferi ticks and mammals
D. Lewandowski, A. Urbanowicz, M. Figlerowicz
24 October 2017

1. Wprowadzenie. 2. Borrelia burgdorferi – podstawowe informacje. 3. Kleszcz jako pasożyt. 4. Kolonizacja kleszcza przez B. burgdorferi. 5. Białka kleszcza wykorzystywane przez B. burgdorferi podczas zakażania organizmu gospodarza. 6. Podsumowanie

Abstract: Over the last decade, the incidence of tick-borne diseases has been rapidly increasing in Poland. Lyme disease cases are especially frequent. They disease in caused by Borrelia burgdorferi spirochetes. The enzootic cycle of the Lyme disease pathogen involves both a mammalian host and an Ixodes tick vector. B. burgdorferi enters the tick during its feeding on an infected vertebrate. To survive in the vector and to enter the host, spirochetes utilize their lipoproteins anchored in the external bacterial membrane and tick-encoded proteins. B. burgdorferi is so well adapted to the vector that it is also capable of employing tick strategies to more effectively infect mammalian hosts.
Tick-Borrelia interaction is a very interesting and complex example of parasitism. Better understanding of the mechanisms underlying this phenomenon is indispensable for the development effective strategies of Lyme disease prophylactics and treatment. Here, we describe how B. burgdorferi alters gene expression depending on the tick or vertebrate environment. We also characterize the key bacterial and vector proteins necessary for spirochete for effective colonization of the tick.

1. Introduction. 2. B. burgdorferi characteristics. 3. Ticks as a parasites. 4. Tick colonization by B. burgdorferi. 5. Tick proteins exploited by B. burgdorferi during host infestation. 6. Summary

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

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