1,721,022 research outputs found
Clonaggio dei geni di Pseudomonas stutzeri OX1 coinvolti nella degradazione di o-xilene e toluene
No full textCatalase A is involved in the response to photooxidative stress in Pseudomonas aeruginosa
No full textBackground: Pseudomonas aeruginosa is the etiological agent of systemic and skin infections that are often difficult to treat. Photodynamic therapy (PDT) and, more recently, phototherapy (PT), are emerging among antimicrobial treatments to be combined with antibiotics. Visible light, either alone or combined with a photo sensitizer (PS), elicits photooxidative stress that induces microbial death. The response of bacteria to phototherapy seems to involve the antioxidant machinery. This study relies on the effects of detoxifying catalase A (KatA) in response to PDT and PT-induced photooxidative stress.Methods: The photo- and photodynamic inactivation experiments have been targeted at P. aeruginosa PAO1 and its isogenic derivative katA(-) mutant. The microorganisms were irradiated by a wide-spectrum halogen-tungsten lamp or light-emitting diodes (LEDs). Two photosensitizers, Tetrakis-(1-methyl-4-pyridyl)-21H, 23porphine, tetra-p-tosylate (TMPyP) porphyrin and Toluidine Blue O (TBO), were applied as part of the photodynamic approach.Results: P. aeruginosa katA(-) mutant was more sensitive than wild-type strain PAO1 to wide-spectrum light and blue LED (464 nm) treatments. The complementation of KatA, in katA(-) mutant, restored the light response of wild-type PAO1. Upon TBO treatment and irradiation by visible light (halogen lamp or LED), the sensitivity of katA(-) mutant was significant higher (p = 0.028 and p = 0.045, respectively) than that of the PAO1 strain.Conclusions: This study provides the first description of KatA in the response to photooxidative stress induced by photo- and photodynamic therapy
Catabolismo di o-xilene e toluene in Pseudomonas stutzeri OX1: identificazione di una fenolo idrossilasi ed indagini preliminari sulla regolazione
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Effect of blue light at 410 and 455 nm on Pseudomonas aeruginosa biofilm
No full textPseudomonas aeruginosa is an opportunistic pathogen resistant to many antibiotics, able to form biofilm and causes serious nosocomial infections. Among anti-Pseudomonas light-based approaches, the recent antimicrobial Blue Light (aBL) treatment seems very promising. The aim of this study was to evaluate the efficiency of blue light in inhibiting and/or eradicating P. aeruginosa biofilm. Light at 410 nm has been identified as successful in inhibiting biofilm formation not only of the model strain PAO1, but also of CAUTI (catheter-associated urinary tract infection) isolates characterized by their ability to form biofilm. Results of this work on 410 nm light also demonstrated that: i) at the lowest tested radiant exposure (75 J cm−2) prevents matrix formation; ii) higher radiant exposures (225 and 450 J cm−2) light impairs the cellular components of biofilm, adherent and planktonic ones; iii) light eradicates with a good rate young and older biofilms in a light dose dependent manner; iv) it is also efficient in inactivating catalase A, a virulence factor playing an important role in pathogenic mechanisms. Light at 455 nm, even if at a lower extent than 410 nm, showed a certain anti-Pseudomonas activity. Furthermore, light at 410 nm caused detrimental effects on enzyme activity of β-galactosidase and catalase A, and changes on plasmid DNA conformation and ortho-nitrophenyl-β-D-galactopyranoside structure. This study supports the potential of blue light for anti-infective and disinfection applications
Clonaggio di geni coinvolti nella degradazione dell'o-xilene in Pseudomonas stutzeri OX1
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Cloning of the genes for and characterization of the early stages of toluene and o-xylene catabolism in Pseudomonas stutzeri OX1
No full textBacterial melanin production by heterologous expression of 4 hydroxyphenylpyruvate dioxygenase from Pseudomonas aeruginosa
No full textPyomelanin is a reddish-brown pigment produced by bacteria of different genera and plays a variety of physiological roles. Proposals have been regarding the use of pyomelanin in various environmental, industrial and, more recently, cosmetic applications. In Pseudomonas aeruginosa, the enzyme 4‐hydroxyphenylpiruvate dioxygenase (Hpd) converts 4-hydroxyphenylpiruvate into homogentisic acid, which represents the key intermediate for melanin biosynthesis. This work aimed to obtain Escherichia coli cells overexpressing hpd gene from the PAO1 strain to produce large amounts of pyomelanin for biotechnological purposes. The recombinant dioxygenase expression gave E. coli JM109 the ability to produce pyomelanin. A series of biotransformations led us to choose the best experimental conditions for pyomelanin production. Cells were grown at the mid-exponential phase in a mineral medium with added glucose 10 mM as carbon and energy sources and casamino acid 0.2% w/v as an amino acid source. The administration of tyrosine 1 mM after 30 min of exposure to arabinose 1% w/v made it possible to purify 213 mg/L of pyomelanin after 6 days of biotransformation. In addition to the interesting biotechnological outcomes, the resulting expression system supports the correlation between the hpd gene from P. aeruginosa PAO1 and pyomelanin synthesis
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