Tarek Moussa

n/a

n/a

n/a

The gene (pox1) encoding a phenol oxidase 1 from Pleurotus ostreatus was sequenced and the corresponding pox1-cDNA was also synthesized, cloned and sequenced. The isolated gene is flanked by an upstream region called the promoter (399 bp) prior to the start codon (ATG). The putative metal-responsive elements (MREs) were determined in the promoter region, where MRE 1, 2 and 3 were located in positions -20, -62 and -389, respectively. Functional TATA consensus sequences were recognized in positions -78 and -245, while CAAT consensus sequence was recognized in position -171. The putative GC boxes consensus sequences were recognized in positions -175 and -344, and xenobiotic-responsive elements (XREs) in positions -100 and -270. The pox1-DNA gene consists of 2656 bp, with the coding sequence being interrupted by 19 introns. The nucleotide sequence of cDNA (pox1-cDNA) was found to contain an ORF of 1590 bp capable of coding for a protein of 529 amino acid residues. The signal peptide was predicted to be 23 amino acids in length using SIGNALP 3.0 program. Northern blot analysis revealed that strong transcriptional induction was observed in the copper-supplemented cultures for pox1 gene.

n/a

n/a

The aim of this study was to evaluate the efficacy of selected bacterial strains against the wheat soil-borne pathogen Fusarium graminearum under greenhouse conditions. The most potent isolates were 3 isolates out of 18 isolates, which have numbers 3, 9 and 10 with in vitro inhibition index 42.5%, 41.3% and 46.3% respectively. Isolates 3 and 10 were selected for the following experiments. Isolates 3 and 10 were identified as Bacillus subtilis MAA03 and Pseudomonas fluorescens MAA10, respectively according to International Identification Keys and, confirmed by using Biolog system and 16S rDNA where the strains exhibited more than 99.5% sequence identity. Their close taxonomic relationship was further documented by phenotypic similarities. The using of B. subtilis and P. fluorescens separately or in mixture as biocontrol agent against F. graminearum on wheat significantly increased the final germination percent, the mean daily germination and germination index of wheat cultivar, while the mean germination time was significantly decreased relative to infested control. The final infection percent, the mean daily infection and infection index were decreased significantly, while the mean infection time was significantly increased relative to infested control. The use of P. fluorescens as biocontrol agent was the most efficient than B. subtilis or in mixture and the best treatment was seed coating. The application of B. subtilis and P. fluorescens separately or in combination significantly affected the growth parameters of wheat cultivar Tabuki, the root length was significantly increased in seed coating and seed soaking treatments, while non-significantly decreased in case of soil drench treatment relative to infested control. Shoot length was significantly decreased in case of seed coating treatment relative to infested control. The shoot fresh and dry weights were significantly increased in seed coating and seed soaking treatments relative to infested control. The root fresh and dry weights were significantly increased in seed coating and seed soaking treatments relative to infested control. The number of leaves was significantly increased in all treatments relative to infested control.

n/a

Extremophiles are a group of organisms growing in a wide range of extreme environmental conditions. The extremophilic microorganisms are diverse and are classified into psychrophiles (− 2°C to 20°C), thermophiles (55–121°C), piezophiles (> 500atm), halophiles (2–5M NaCl or KCl), metallophiles (high concentrations of metals, e.g., copper, zinc, lead, cadmium, and arsenic), alkaliphiles (pH>8), and acidophiles (pH<4) according to the extreme environmental conditions in which they grow and can tolerate. The aims of this chapter are to characterize the extremophilic microorganisms and their physiological and molecular efficiencies in bioremediation processes. Interestingly, the remarkable adaptative abilities of extremophilic microorganisms make them an attractive source of biocatalysts for bioremediation. Bioremediation is an important technology for the cleanup of environmental contaminants. Further attention has also been directed to isolation, identification, and characterization of biocatalysts from extremophilic microorganisms, most of them enzymes named extremozymes, which are well adapted to be active also at extreme conditions. Extremozymes are expected to fill the gap between biological and chemical industrial processes because of the remarkable properties of these enzymes. Even though more than 3000 different enzymes have been identified till now, and many of these were used in industrial and biotechnological applications, the enzyme toolbox at the present is still not enough to present demands. A major cause for this is the fact that many available enzymes do not withstand industrial reaction conditions.

n/a

The ability to produce cellulose degrading enzymes by sugarbeet pathogen Sclerotium rolfsii Sacc. in liquid synthetic media with carboxymethy cellulose (CMC) as inducer was studied. Several cultural conditions were examined to assess their effect in optimizing enzymes production. Shaking cultures gave higher yields of cellulases compared with static ones. Aspargine supplement was the best nitrogen source, especially at 3.0 g/l concentration, in promoting enzyme production. Variation of cellulose/xylan ratio in the culture medium showed that cellulose and xylan induced both cellulases synthesis but cellulose being the most effective specific substrate. The influence of different inhibitors on enzymes production by S. rolfsii was also studied. Cyclohexmide and ethidium bromide inhibited protein synthesis by S. rolfsii. Moreover, glucose repressed cellulase synthesis in S. rolfsii.