All posts by Postępy Mikrobiologii

Symbioza rizobiów z roślinami bobowatymi (Fabaceae)

Symbiosis of rhizobia with legume plants (Fabaceae)
G. Stasiak, A. Mazur, P. Koper, K. Żebracki, A. Skorupska

1. Znaczenie biologicznego wiązania azotu (BNF). 2. Partnerzy symbiozy. 3. Etapy symbiozy. 3.1. Inicjacja symbiozy. 3.2. Rozwój brodawki. 3.3. Typy brodawek korzeniowych. 4. Wiązanie azotu. 5. Genomy rizobiów. 6. Chromidy i megaplazmidy. 7. Plastyczność genomów rizobiów. 8. Podsumowanie

Abstract: Biological nitrogen fixation is one of the most important processes in which atmospheric nitrogen is reduced to ammonia by symbiotic bacteria called rhizobia, which belong to α- and β-proteobacteria. Legume plants (Fabaceae) have the capacity to enter into mutualistic symbiosis with nitrogen-fixing bacteria, enabling them to grow in nitrogen-limited agricultural soils. In these specific associations, new organs called root or shoot nodules are developed. Infection of plants by rhizobia is a series of sequential stages in which rhizobial lipochitooligosaccharide, called the Nod factor, activates plant transmission signaling and initiates nodule development. In the nodules the bacteria multiply and differentiate into nitrogen-fixing bacteroids. In return for reduced nitrogen compounds provided to the plants, rhizobia are supplied with plant carbon photosynthetic products and are protected from environmental stresses.
Genomes of rhizobia and other soil bacteria are large and multipartite, composed of the chromosome and plasmids (megaplasmids), which may comprise up to 50% of the genome. A common feature of the rhizobial genomes is that genes responsible for nodulation and nitrogen fixation are clustered on symbiotic plasmids (pSym) or incorporated into the chromosome as symbiotic islands. Plasmids are heterogeneous in size and gene content even in closely related rhizobia. Recently described extrachromosomal replicons, named “chromids”, have some chromosome and plasmid properties and are essential for bacterial growth under natural and laboratory conditions. The special architecture of rhizobial genomes may cause their dynamic state and plasticity, leading to significant diversity of rhizobia on the genetic and metabolic levels.

1. The importance of biological nitrogen fixation (BNF). 2. Symbiosis partners. 3. Symbiosis stages. 3.1. Initiation of symbiosis. 3.2. Nodule development. 3.3. Types of nodules. 4. Nitrogen fixation. 5. Rhizobial genomes. 6. Chromids and megaplasmids. 7. Plasticity of rhizobial genomes. 8. Summary

Związki interferujące z bakteryjnymi systemami wyczuwania liczebności i ich potencjalna funkcja terapeutyczna

Inhibitors of bacterial quorum sensing systems and their role as potential therapeutics
K. I. Wolska, A. M. Grudniak, K. Markowska

1. Wprowadzenie. 2. Wyczuwanie liczebności jako sposób komunikowania się bakterii. 3. Organiczne inhibitory QS. 3.1. Inhibitory roślinne. 3.2. Inhibitory pochodzenia zwierzęcego. 3.3. Inhibitory produkowane przez bakterie. 4. Hamowanie QS przez nanocząstki. 5. Uwagi końcowe

Abstact: Quorum sensing (QS) is a commonly used way of cell-to-cell communication which plays a role in the regulation of gene expression and, therefore, controls bacterial social behavior and pathogenicity. The inhibition of QS, called quorum quenching (QQ), is considered as a promising strategy to combat bacterial infections without severe influence on bacterial survival. To date, several anti-QS approaches have been documented. In this article, two groups of potent QS inhibitors are described: 1) natural, organic compounds isolated from plants, animals and bacteria and 2) various types of nanoparticles. The ability of the sublethal concentration of these compounds to inhibit QS autoinducers synthesis as well as various steps of QS-regulated cellular response, and thus virulent traits of bacterial pathogens such as biofilm development, are discussed. QS inhibitors can constitute the promising future alternative to antibiotics, especially since until now, the development of bacterial resistance to neither group of these compounds has been reported.

1. Introduction. 2. Quorum sensing as a system of bacterial communication. 3. Organic inhibitors of QS. 3.1. Plant compounds. 3.2. Inhibitors of animal origin. 3.3. Inhibitors synthesized by bacteria. 4. QS inhibition by nanoparticles. 5. Concluding remarks

Wybrane metody molekularne wykorzystywane w ocenie bioróżnorodności mikroorganizmów glebowych

Selected molecular methods used in assessing the biodiversity of soil organisms
M. Łyszcz, A. Gałązka

1. Wstęp. 2. Metody klasyczne stosowane do identyfikacji bakterii. 3. Metody molekularne stosowane do identyfikacji mikroorganizmów glebowych. 4. Analiza zawartości zasad G+C w DNA. 5. Hybrydyzacja kwasów nukleinowych. 6. Analiza sekwencji kwasów nukleinowych. 7. Podsumowanie

Abstract: Biodiversity and the identification of new important features of microorganisms is crucial for the development of biotechnology. The current knowledge about microbs in natural environments is limited, thus the analysis of the microbial diversity in nature is not an easy task. So far, only a small percentage of prokaryotic microorganisms has been identified. It is believed that the soil environment is one of the richest reservoirs of microorganisms, as approximately 2 000 to 18 000 prokaryotic genomes can be isolated from one gram of soil. In this publication the selected methods used to identify microorganisms are presented. The first molecular marker used in the genetic identification of soil microorganisms was the analysis of the G+C base content, sincemicroorganisms exhibit differences in the (G+C)/(A+T) relative factor. Another method used to identify bacteria is the nucleic acid hybridization. This technique involves a determination of the degree of similarity of DNA-DNA between two organisms. One of the most frequently used hybridization technique is FISH – fluorescent in situ hybridization. The most precise method for analyzing the nucleic acids is sequencing, i.e. determining the order of nucleotides which form the genetic information of the microorganism studied. Very often in molecular studies the 16S rDNA molecule is subjected to sequencing.

1. Introduction. 2. Classical methods used to identify bacteria. 3. Molecular methods used in the identification of soil microorganisms. 4. Analysis of the G+C DNA content. 5. Nucleic acid hybridization. 6. Analysis of nucleic acid sequences. 7. Summary

Właściwości i zastosowanie podłoży bakteriologicznych

Properties and uses of bacteriological media
A. Mikołajczyk, E. Stefaniuk, K. Bosacka, W. Hryniewicz

1. Wstęp. 2. Przygotowywanie i przechowywanie podłoży. 3. Kontrola jakości. 4. Podział podłoży. 4.1. Podział ze względu na skład chemiczny. 4.2. Podział ze względu na konsystencję. 4.3. Podział ze względu na zawartość substancji odżywczych. 4.4. Podział ze względu na zastosowanie. 5. Podsumowanie

Abstract: The aim of this article was to collate information about bacteriological media, presenting their composition, properties and the resultingpossible applications of a particular medium or group of media in bacteriological diagnostics. The most important groups of culture media were classified basing on their composition (synthetic, semi-synthetic and natural), consistency (liquid, semi-solid, solid), nutrient content (minimum, nutrient-enriched) and use (transport, nutrient, selective, differential, selective-differentiating, for susceptibility testing). Taking into account the practical aspect, much space is devoted to the classification of culture media based on their possible use. For each group, several examples of culture media with their major components and bacterial species for which they are intended are given. Brief information about the quality assurance and control of media during their preparation, transport and storage is also presented.

1. Introduction. 2. Preparation and storage of media. 3. Quality control. 4. Classification of culture media. 4.1. Classification of culture media based on their composition. 4.2. Classification of culture media based on their consistency. 4.3. Classification of culture media based on their nutrient content. 4.4. Classification of culture media based on their use. 5. Summary

Probiotyki, a układ odpornościowy przewodu pokarmowego ssaków

Probiotics and mammalian gastrointestinal immune system
B. Tokarz-Deptuła, W. Deptuła

1. Wstęp. 2. Probiotyki, a układ odpornościowy przewodu pokarmowego. 3. Podsumowanie

Abstract: Probiotics are microorganisms that provide health benefits when consumed. These are also food supplements or food products containing specified probiotic microorganisms. Probiotic microorganisms colonize the gastrointestinal tract of the host environment, reducing the risk of pathogenic bacteria growth and their potential impact on the regulation of host immune responses. They also have the ability to eliminate pathogenic bacteria. The administration of probiotic microorganisms in addition to chemotherapeutic agents and antibiotics improves therapy efficiency, since it results in restoration of the equilibrium between the local and general pro- and anti-inflammatory response.

1. Introduction. 2. The probiotics and the gastrointestinal immune system. 3. Conclusions

Najnowszy numer

Najnowszy numer

POSTĘPY MIKROBIOLOGII
2018, 57, 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.