Wyniki wyszukiwania - Biblioteka Nauki

1

Enzymatic degradation of acyl-homoserine lactones and its possible use in biocontrol and suppression of infection development

100%

Czajkowski R. , Jafra S.

Biotechnologia

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2006

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nr 2

49-64

EN

A large number of different bacteria populations control diverse metabolic processes through production and distribution of specific signal molecules, which concentration in the environment depends on bacteria cell density and rise when bacteria population expands. This strategy is known as quorum sensing (QS), and was first described in Gram-negative, marine bacterium Vibrio fischeri. QS, a mechanism of gene expression regulation dependent on bacterial cell density, is widely distributed in Gram-negative bacteria; and controls different physiological processes such as production of virulence factors, conjugal plasmid transfer, antibiotic production, replication, swarming or luminescence. QS functions via signal molecules: in Gram-negative bacteria, the signal molecules belong to the acyl-homoserine lactones (AHLs). It was found that many bacteria possess the ability to interfere in QS (strategy known as quorum quenching- QQ) by enzymatic degradation of AHLs. Till now, two classes of enzymes able to degrade AHLs have been described: AHL-lactonases and AHL-acylases. AHL-lactonases hydrolyze the ester bond in the lactone ring of AHLs. AHL-acylases hydrolyze the amide bond between the acyl side chain and the lactone ring in AHLs. Both reactions lead to the inhibition of signal transfer in QS as degradation products cannot act as signal molecules. QS plays a major role in pathogenesis and as such is deeply studied as a useful target for modern, antimicrobial therapy in human medicine and veterinary, as well as in biocontrol of plant diseases.

2

Characteristcs and regulation of the expression of genes coding Erwinia pectinases and its significance for soft rot disease

100%

Jafra S. , Lojkowska E.

Biotechnologia

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1999

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nr 2

104-119

EN

The enterobacterium Erwinia causes soft rot disease in various plants. Erwinia pathogenicity results from the secretion of pectinolytic and cellulolytic enzymes responsible for the deterioration of the plant cell wall. It produces pectin methylesterases, several pectate lyases, polygalacturonase, pectin lyase, cellulases and hemicellulase. Regulation of pectinases genes requires several regulatory systems. Deletion of the major pectate lyase genes from Erwinia genome failed to totally eliminate tissue maceration. Structural genes for secondary pectate lyase were cloned and sequenced. The important role of the secondary pelL gene in the development of infection was demonstrated.

3

Expression of Erwinia chrysanthemi genes coding pectate lyases in infected potato tissue

100%

Jafra S. , Lojkowska E.

Biotechnologia

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2000

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nr 3

202-214

EN

Erwinia chrysanthemi mutants, containing transcriptional fusion of one of the pectate lyase genes (pelA, pelB, pelC, pelD, pelE, pelI, pelL, pelZ) with the reporter gene encoding b-glucuronidase activity, were studied for their ability to cause disease symptoms and to synthesise pectinases after inoculation of potato tubers. The strains affected in pelI and pelL genes displayed a reduced virulence on potato tubers demonstrating the important role of these isoenzymes in soft rot disease. Analysis of the bacterial population showed an active multiplication of bacteria during the infection. Similar kinetics of growth were observed for all mutants and for the wild type strain. Comparison of the mutants and the wild type strain showed that the pelI, pelL and pelZ mutants synthesised reduced levels of Pels. The expression of pelA, pelE and pelZ is 5-fold higher in planta than in in vitro. In contrast, both pelI and pelL are highly (10-fold factor) induced in planta, which is characteristic of the plant-inducible pectate lyases.

4

Ability for biodegradation and bioadsorption of the bacteria from Ochrobactrum genus important in bioremediation

100%

Poddebniak M. , Jafra S.

Biotechnologia

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2009

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nr 4

152-167

EN

Bacteria from Ochrobactrum genus are found in various environments. They were isolated from soil, sewage, plant tissue and human body, where they acted as a human opportunistic pathogens. Ochrobactrum are able to degrade a wide variety of chemical substances, such as atrazine, nicotine, phenol or polycyclic aromatic hydrocarbons (PAH) and accumulate heavy metals. Many of those substances pose a threat to the environment and to mankind. The representatives of this genus also play an important role in the nitrogen cycle as one of the symbiotic bacteria of legume plants that reduce nitrites to atmospheric nitrogen. There is still little information about the genus Ochrobactrum and this is why it is necessary to focus more attention on it in terms of environmental protection.