Antibacterial activity of the white lily Moringa oleifera seed extract and its use in water treatment

Abstract

White lily Moringa oleifera seed powder acts as a natural coagulant promoting the reduction of water turbidity by the coagulation and sedimentation of the suspended particles, also eliminating the microorganisms by sedimentation. The aqueous extract of M. oleifera presented an inhibitory capacity for the growth of Staphylococcus aureus, whereas the hydroalcoholic extract inhibited S. aureus, Salmonella typhimurium and Vibrio cholerae, using the agar diffusion test. Standard strains of Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis were resistant to the extracts. The water treatment through the aqueous extract of M. oleifera seeds at 0.02% and 0.01% concentrations was evaluated with the water samples collected in the Sinibu River, Paraíba State, Brazil, using the jar test. The water samples analyzed in this work were characterized by low turbidity (2.8-3.0 NTU), and pH and alkalinity between 5.8-7.3 and 10-30 mg CaCO3/L, respectively. After water treatment with M. oleifera aqueous extract, it was observed that pH, turbidity and alkalinity did not change significantly. Total heterotrophic bacteria counts in the crude water samples were between 1.9 x 10^5 UFC/100 mL and 1.1 x 10^6 CFU/100 mL, while the number of fecal coliforms was between 2.3 x 10^2 NMP/100 mL and 2.4 x 10^3 NMP/100 mL. The counts of total bacteria and fecal coliforms in the water samples treated with aqueous white lily extract at both concentrations tested (0.02% and 0.01%) during the 1.5-hour period did not differ significantly when compared to the untreated water. The results obtained in this work indicate that low turbidity of water influenced the efficacy of M. oleifera extract in the removal of bacteria in the treated water, since the level of coagulation depends on water turbidity.