Biologie

Environmental and hospital-sampling allowed us to isolate and identify one hundred of Pseudomonas aeruginosa (P. aeruginosa) strains. The study of the degradation capacity of alkanes has shown that almost all isolates grew in the presence of long chain n-alkanes, while no growth was recorded in the presence of short chain n-alkanes, isoalkanes or cycloalkanes. The kinetics of growth in the presence of hexadecane, as a sole carbon source, enabled recording various optical densities (OD) depending on the strain of P. aeruginosa. The polymerase chain reaction (PCR) in the presence of ERIC (Enterobacterial repetitive intergenic consensus) primers has shown genetic diversity within isolates. The search for alkB and alkB1 genes, which are respectively responsible for the degradation of short chain n-alkanes and long chain n-alkanes, has shown the absence of alkB gene; however, the alkB1 gene, strongly present within the population of P. aeruginosa isolated, is absent in a few strains despite their ability to degrade long chain n-alkanes. The nucleotide sequencing of a alkB1 gene fragment for 4 P. aeruginosa strains as well as the reference strain P. aeruginosa PAO-1 has shown a highly conserved nucleotide sequences in spite of their heterogeneity origin.

Environmental and hospital-sampling allowed us to isolate and identify one hundred of Pseudomonas aeruginosa (P. aeruginosa) strains. The study of the degradation capacity of alkanes has shown that almost all isolates grew in the presence of long chain n-alkanes, while no growth was recorded in the presence of short chain n-alkanes, isoalkanes or cycloalkanes. The kinetics of growth in the presence of hexadecane, as a sole carbon source, enabled recording various optical densities (OD) depending on the strain of P. aeruginosa. The polymerase chain reaction (PCR) in the presence of ERIC (Enterobacterial repetitive intergenic consensus) primers has shown genetic diversity within isolates. The search for alkB and alkB1 genes, which are respectively responsible for the degradation of short chain n-alkanes and long chain n-alkanes, has shown the absence of alkB gene; however, the alkB1 gene, strongly present within the population of P. aeruginosa isolated, is absent in a few strains desp...

The ability of biofilms formation was studied by utilizing fifty Pseudomonas aeruginosa strains isolated from both environmental and hospital samples. The support utilized for strains fixation was in polystyrene and contained two liquid media: Luria-Bertani and Mineral Medium supplemented with Hexadecane as the sole source of carbon and energy. The results obtained showed that the Biofilms-forming ability depend on both media carbon source and the P. aeruginosa strain variety. When the carbon source is hard to degrade or toxic, like hexadecane or derived substrates, the formed biofilms presented a high density; however, when the carbon is easy to degrade by the strains; like that one of L.B medium, the formed biofilms have a slight density. Furthermore, this density is also influenced by the strains although they belonged to the same species; at this purpose, the ERIC -PCR analysis, showed that P. aeruginosa strains studied are various because their profil ERIC present a percentage ...

From 123 clinical and environmental Pseudomonas aeruginosa isolates, 24 strains were selected for their similar antibioresistance, virulence and biofilm formation profiles, to examine their diversity and occurrence of clones within two hospitals and different natural sites in Meknes (Morocco). Pulsed-field gel electrophoresis, using DraI enzyme, didn't reveal a close relationship between clinical and environmental isolates nor between strains of the two hospitals. 19 genotypes were obtained, including two virulent environmental clones and three clinical clones virulent and resistant to antibiotics. Intra-hospital transmission of high-risk clones detected, in and between wards, constitutes a great public health concern.