الفهرس 
Field collection and samples preparationOnly 14 pages are availabe for public view
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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.