الفهرس | Only 14 pages are availabe for public view |
Abstract Different microbial active constituents have been isolated from various species of algae. The increased use of antibiotics and chemotherapeutants for human disease treatment leads to problems of emergence of drug resistant forms and also impact adverse effects on the ecosystem. Algae represent a great source of biomolecules with wide spectrum effects useful in different biotechnological fields. During this study, different algal extracts were tested as antibacterial substances against three pathogenic bacteria (Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aurues). By using BG11 media, three species of green algae (Scenedesmus obliquus, Cosmariun sp and Rhizoclonium hieroglyphicum) were isolated from different fresh water resources in Kafr Elsheikh Governorate. Three organic solvents (Ethanol, Methanol and Acetone) were used for algal extraction. Four concentrations were used 5, 10, 20 and 40 mg/ml. Antibacterial activity of the four concentrations of each algal extract were determined by agar disc diffusion assay method. The MIC values were studied for the microorganisms that were susceptible in the antimicrobial activity test. MIC value of the algal extracts was determined by broth dilution assay method. Extracts were subjected to serial dilutions to give final concentrations between 0.225 and 40.00 mg/ml. Ethanol extract of Rhizoclonium hieroglyphicum was recorded MICs values with both Gram-positive and Gram-negative bacteria (0.53, 2.25, 5.34 mg/ml) against P. aeruginosa, E. coli and S. aureus, respectively. X Ethanol extract of Cosmarium sp was recorded MICs values with both Gram-positive and Gram-negative bacteria (1.68, 2.25, 3.0 mg/ml) against S. aureus, E. coli and P. aeruginosa, respectively. Ethanol extract of Scenedesmus obliquus was recorded MICs values with both Grampositive and Gram-negative bacteria (2.25, 7.12, 9.5 mg/ml) against E. coli, P. aeruginosa and S. aureus, respectively. P. aeruginosa was more susceptible to the algal extracts. Seven antibiotics were used as control for the three pathogenic bacteria Ampicillin; Amoxicillin; Cefadroxil; Doxycycline; Cefoxitin; Ofloxacin; Vancomycin. P. aeruginosa was more resistant to the antibiotics used. GC-MS analysis was used to determine the chemical composition of the antibacterial substances of algal extracts and identify the most active compound of the algal extracts. Ethanolic extracts of algal species contain many bioactive compounds which have antibacterial effects such as fatty acids, phenolic compounds, esters, ethers, aldehydes and hydrocarbons….etc. |