Aplicación de métodos cromatográficos y bioautográficos para la determinación de actividad antibacteriana e identificación de la fracción activa frente a Staphylococcus aureus y Enterococcus faecalis, de un extracto de actinobacteria marina “Streptomyces sp. MJG-05

Abstract

From Streptomyces's culture labeled as "MJG-05" and by means of the extraction with AcOEt and CH3(CO)CH3, 1,212g of crude extract was obtained. By means of chromatography in Sephadex LH-20 using CHCl3:MeOH (1:1) 31 fractions were obtained (F1-F31) which were gathered in 6 subfractions (F1-F6). The subfraction F2 was chosen (due to its high yield and its good biological activity) for a second fractionation using a mixture of Hex:CHCl3:MeOH (2:1:1), where 7 subfractions where finally obtained (F2f1 - F2f7) gathered by his chromatographic similarity. In the tests of biological activity, there was demonstrated that the Fraction F1, F2 and F2f2, they presented the highest antibacterial activity against Staphylococcus aureus and Enterococcus faecalis, with CMI's values between 62,5 and 15,625 µg/ml. By means of Bioautography agar overlay with Staphylococcus aureus as the reference bacterium, there were detected 5 spots differentiated by his respective factors of delay, the same ones who presented zones of inhibition of the bacterial growth, revealed as absence of color due to the no reduction of the tetrazolio salt.