Antibacterial effects of of some algae of chlorophyta (chlorella vulgaris, scenedesmus obliquus) and cyanophyta (spirulina platensis) groups

It is well known that algae, which are also consumed as food, have antibacterial, antifungal, antiviral, antiparasitic, antioxidant and anticarcinogenic effects due to the many phytocomponents they contain. In this thesis, the algae Chlorella vulgaris and Scedenesmus obliquus from the Chlorophyta group and Spirulina platensis from the Cyanophyta have been used to investigate their antibacterial activities and essential oil components. For these purposes, algae were extracted with 10% ethanol and methanol for 48 hours for antibacterial analysis, and the solvents were removed in a rotary evaporator at 92°C. The 10% stock solutions of the obtained algae extracts were prepared with dimethyl sulfoxide (DMSO). Antibacterial tests were conducted with 10%, 5%, 1% and 0.1% dilutions of the stock solutions. In antibacterial activity measurements, the effect of methanol and ethanol dilutions of algae on Gram-negative (Escherichia coli and Yersinia ruckeri) and Gram-positive (Staphylococcus aureus and Enterococcus faecalis) bacteria were examined. For this aim, disc diffusion, minimal inhibition concentration (MIC) and minimum bactericidal concentration (MBC) tests were applied. Additionally, 25% methanol extracts were prepared for the analysis of the oil components of algae by gas chromatography-mass spectrometry (GC-MS). According to the antibacterial activity measurement results, only 10% methanol extract of S. platensis had an antibacterial effect against Staphylococcus aureus (15-16 mm zone diameter); it was determined that the minimal inhibition concentration was 8 mg/L and the minimum bactericidal concentration was 16 mg/L. It was observed that the ethanol and methanol extracts of the other two algae and the ethanol extract of S. platensis did not have any antibacterial effects. According to GC-MS analysis of the algae, there are a total of 23 oil members. Oleic acid, which was detected at the highest rate in all three algae, was present at 69.31% in S. platensis, 51.67% in C. vulgaris and 27.42% in S. obliquus. In line with these data, a contribution has been made to the antibacterial effect of microalgae, which has been shown by many studies to have an important place in human health. There are great benefits in continuing further research with advanced techniques on the health-related possibilities of nutritious, protective and therapeutic algae, which are widely found in nature. There are great benefits in continuing research that reveals the health effects of nutritional, protective and therapeutic algae, which are widely found in nature, with advanced techniques.