The effect of microalgae extracts Chlorella sp. in some pathogenic microbes

Abstract

Microalgae are a rich source of biologically active compounds and have a potential role in inhibiting the growth of human pathogens. In this study, the effect of four extracts of different organic solvents (propanol, methanol, chloroform and acetone) of green microalgae Chlorella sp. was tested on two Gram positive strains (staphylococcus aureus, Micrococcus sp.), three Gram negative strains (Escherichia coli, Pseudomonas aeroginosa, Klebsiella sp.) And fungal strain (Candida sp.) from local environment. After the isolation of the species Chlorella sp. by using streaking agar method, algae was grown in flasks containing the algae culture medium within an algae incubator. The daily cell count was performed and the growth curve was determined, biomass was harvested at the end of the exponential growth phase on the tenth day. Extraction was made by the four solvents and applied on the different bacterial strains by diffusion wells, then the growth inhibition aura diameter was measured for each of them.

Results indicated that the highest extraction yield as a percentage of Chlorella sp. was recorded with methanol and chloroform at (4.4 and 4%) respectively, while the lowest was for acetone and propanol (1.9 and 1.8%), respectively. The extracts with the lowest yield had recorded high inhibition activity and the greatest influence of acetone extract was on Klebsiella sp. with average diameter of its inhibitory aura (2.5 ± 0.2) cm. Micrococcus sp. significantly affected by propanol extracts with average of (2 ± 0.6) cm, while the lower inhibitory effect on P. aeruginosa an average diameter of (1.3 ± 0.3) cm. In contrast, the E. coli strain exhibited complete resistance to all extracts, as well as Candida sp. except for the weak effectiveness of the methanol extract in its growth. It has also been observed that (MIC) Minimal Inhibitory Concentrations of acetone extract of Chlorella algae are less on Gram positive strains, thus they are more sensitive to acetone extracts than Gram negative strains.