Antibacterial properties of the organic extract of the brown alga Cystoseria trinodis and the green alga Halimeda tuna of the Oman Sea against Escherichia coli, Listeria monocytogenes and Pseudomonas aeruginosa

Resistance to multiple drugs during antibiotic treatment is a new problem. According to research, seaweed extracts have antimicrobial properties. The aim of this study was to investigate the antibacterial properties of organic extracts of Cystoseira trinodis (brown algae) and Halimeda tuna (green algae) of the Oman Sea on E. coli, L. monocytogenes and P. aeruginosa

The algae were dried and the extraction was performed by sonication with ethyl acetate solvent. Antibacterial effects were determined by disk agar diffusion methods, the minimum inhibitory concentration (MIC) was determined by microdilution method and the minimum lethal concentration (MBC) was determined by purplate method.

The antibiotics gentamicin, ampicillin and neomycin showed a significant difference with most of the extracts and had more inhibitory power (P <0.05). Ethyl acetate extract of C. trinodis against P aeruginosa did not show a significant difference with neomycin antibiotic in the ratio of 1.5 w / v with the diameter of the growth inhibition zone of 11.91 mm (p <0.05). The diameter of the growth inhibition zone of this extract against E. coli was 10.33 mm. The diameter of the growth inhibition zone of H. tuna against E. coli and P. aeruginosa was 12.01 and 11.3 mm, respectively. MIC of 3.08 mg/ml for C. trinodis extract and MBC of 9.75 mg/ml for H. tuna extract was found against P. aeruginosa. P. aeruginosa showed the highest susceptibility to extracts among the three bacteria and L. monocytogenes showed no susceptibility to extracts.

Ethyl acetate extract of brown algae C. trinodis has an antibacterial effect against P. aeruginosa; equivalent to the antibiotic neomycin and ethyl acetate extract of H. tuna algae has a lethal effect against P. aeruginosa.