بررسی آزمایشگاهی اثر ضد باکتریایی عصاره اتیل‌استاتی جلبک دریایی قرمز (Gelidiella acerosa) بر برخی باکتری‌های گرم مثبت و گرم منفی

Background and Objectives: Nowadays, the excessive use of antibiotics has caused bacteria to develop new resistant forms, so that discovering bioactive antimicrobial compounds has been considered by researchers. The aim of this study was to evaluate the antibacterial effect of ethyl acetate extract of red algae (Gelidiella acerosa) on some gram-positive and gram-negative bacteria in laboratory conditions. Materials and methods: In this in vitro study, 4 different concentrations of 10-80 mg/ml of ethyl acetate extracts were tested on 3 strains of gram-positive bacteria (Lactoccocus garviae، Listeria monocytogenes ,and Staphylococcus aureus) and 4 strains of gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae، Proteus vulgaris, and Photobacterium damselae), using disc diffusion technique and measuring growth inhibition zone. The results were compared with two standard antibiotics. In this study, minimum inhibitory concentration (MIC) test was conducted using serial dilutions method. One-way ANOVA was used to compare the mean differences among the different groups, and Duncan&rsquo;s test was used to determine the mean differences between pairs of groups. Results: In this study, K. pneumoniae bacteria showed more sensitivity against algae extract with a growth inhibition zone diameter of 12.50&plusmn;1.33 mm at concentration of 80 mg/ml, which was significant (p<0.05) compared to the tetracycline antibiotic and the other concentrations, although it was not significant compared to the neomycin antibiotic (p>0.05). Conclusion: The results of this study showed that the ethyl acetate extract of red algae (Gelidiella acerosa) , in laboratory conditions, has greater antibacterial effect on K. pneumoniae, E. coli, L. garviae and P. damsella microrganisms. Keywords: Antibacterial effect, Ethyl acetate extract, Red algae Funding: This study was partially funded by Chabahar University of Maritime and Marine Sciences. Conflict of interests: None declared. Ethical Approval: The Ethics Committee of Chabahar University of Maritime and Marine Sciences approved the study. How to cite this article: Ghaffari M, Taheri A, Zobeidinezhad M. In vitro Evaluation of Antibacterial Effect of Ethyl Acetate Extract of Red Algae (Gelidiella acerosa) on Some Gram-positive and Gram-negative Bacteria J Rafsanjan Univ Med Sci 2016; 15(3): 209-22. [Farsi]