Tarek Moussa

The gene (pox2) encoding a phenol oxidase from Pleurotus ostreatus, a lignin-degrading basidiomycete, was sequenced and the corresponding pox2-cDNA was also synthesized, cloned and sequenced. The isolated gene consisted of 2674 bp, with the coding sequence interrupted by 19 introns and flanked by an upstream region in which the putative metal-responsive elements (MREs) were determined in the promoter region (849 bp), where MRE 1, 2, 3 and 4 were located in positions - 20, - 60, - 236 and - 297. A functional TATA consensus sequence was recognized in position - 85, while CAAT and its inversion consensus sequences were recognized in positions - 284, - 554, - 689 and - 752. The putative GC box consensus sequences were recognized in positions - 181 and - 460, and xenobiotic-responsive elements in positions - 107, - 277 and - 390. The isolation of a second cDNA (pox2-cDNA), the nucleotide sequence of pox2, was found to contain an ORF of 1665 bp capable of coding for a protein of 533 amino acid residues. Northern blot analysis revealed that strong transcriptional induction was observed in the copper-supplemented cultures for the pox2 gene.

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Diarrheagenic Escherichia coli (DEC) are important enteric pathogens that cause a wide variety of gastrointestinal diseases, particularly in children. Escherichia coli isolates cultured from 243 diarrheal stool samples obtained from Libyan children and 50 water samples were screened by polymerase chain reaction (PCR) for genes characteristic of enteroaggregative E. coli (EAEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enterohemorrhagic E. coli (EHEC), and enteroinvasive E. coli (EIEC). The DEC were detected in 21 (8.6%) children with diarrhea; 10 (4.1%) cases were identified as EAEC, 3 (1.2%) as EPEC, and 8 (3.3%) were ETEC; EHEC, and EIEC were not detected. All DEC were grouped phylogenetically by PCR with the majority (> 70%) identified as phylogenetic groups A and B1. The EAEC isolates were also tested for eight genes associated with virulence using PCR. Multi-virulence (>= 3 virulence factors) was found in 50% of EAEC isolates. Isolated EAEC possessed different virulence traits and belonged to different phylogenetic groups indicating their heterogeneity.

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The value of maximum specific growth rate (mu(max) = 0.0177 h(-1)), the maximum growth value (X(max)= 1.82 g l(-1)) The initial biomass concentration was calculated (X(o) = 0.0285 g l(-1)), the maintenance coefficient (K(c) = 0.245 g g(-1)h(-1)), the biomass yield (Y(X/S) = 0.039 g g(-1)) and the product yield (Y(P/S) = 0.0828 g g(-1)) were calculated from the model. The presented model provided a satisfactory representation of the biomass growth; biosurfactant production. The average error of biomass growth and biosurfactant production were 10.2 and 5.7%; respectively. The present model gave a satisfactory representation of the biomass growth; whereas the average percentage error in biosurfactant production through the fermentation process was 5.74% and in microorganism concentration was 10.172%.