Evaluación del potencial antibacteriano en extractos lipofílicos de cianobacterias y microalgas cultivadas a partir de muestras de agua recolectadas en el sector del Cajas

Abstract

Currently, it is known that there are more than 30,000 species of cyanobacteria and microalgae taxonomically characterized. Very few of them have been studied chemically and pharmacologically. This lack of information is even more critical when it is considered to freshwater species from tropical Andean lakes; therefore, it is important to evaluate the presence or absence of the biological potential in organisms from this region. In this research, the possible antibacterial effect of six lipophilic extracts of cyanobacteria and microalgae obtained by maceration with dichloromethane from cultivated species were evaluated against Staphylococcus aureus (S. aureus). Those organisms were cultivated at the Laboratory of Microalgae from the VLIR Project from samples previously collected in small bodies of water in the sector of "El Cajas" of the city of Cuenca - Ecuador (four cyanobacteria, one fresh water microalgae and an existing inoculum from the Laboratory of Aquatic Ecology, Evolution and Conservation of the University of Leuven - Belgium (marine microalgae)). This research had 3 phases: the first one was the culture of each species in its specific medium under the adjust at some physical and chemical parameters until collecting sufficient biomass. The second phase, named extraction included processes such as lyophilization of the biomass, maceration with repeated ultrasound application and finally the removal of the solvent from the extract under vacuum and its preservation. The last one consisted in the evaluation of the antibacterial potential against the strains of S. aureus (ATCC 25923) by modifying the plate microdilution method (direct dissolution of the lipophilic extract in trypticase soy broth with tween 80). The results indicated that the four cyanobacteria codified as Flores #1, Koenraad #10, Tamariz #5 and Tamariz # 6 and the marine microalgae Tamariz #12 do not possess an antibacterial potential against S. aureus (ATCC 25923), while the sweet water microalgae Tamariz #11 possesses a slight active potential (IC 50: 7.13 µg/mL) manifesting a bacteriostatic mechanism. However, the presented difficulties in achieving a complete dissolution of cyanobacteria´s and microalgae’s lipophilic extracts prior to the development of the biological activity measurement, it suggests the necessity to develop a deeper research about methodologies that allows the complete solubilization of them in order to completely trust on results coming from this type of products.