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

Tânia Maria De Andrade,Krystyna Gorlach-Lira

doi:10.21472/bjbs.051108

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.

Highlights

Coagulation and flocculation followed by sedimentation, filtration, and chlorine-based disinfection are used as steps in a conventional treatment prior to the distribution of treated water to consumers (Edzwald et al, 1989)
Moringa seed powder as a natural coagulant promotes the reduction of water turbidity by the coagulation and sedimentation of the suspended particles, as well as the elimination of pathogenic microorganisms by sedimentation, since most of the microbes are bound to the suspended particles
Regarding to the analysis of antibacterial activity of the aqueous extract of M. oleifera seeds, in this work was observed that among the pathogenic bacteria tested only S. aureus was inhibited by aqueous extract of M. oleifera seeds, with minimum inhibitory concentration of 0.25% of the extract (Table 1)

Summary

Introduction

Coagulation and flocculation followed by sedimentation, filtration, and chlorine-based disinfection are used as steps in a conventional treatment prior to the distribution of treated water to consumers (Edzwald et al, 1989). The cost and adverse environmental effects of these compounds increased the interest in using organic coagulants or flocculants from plant material, such as Moringa oleifera seeds, for water treatment (Jahn et al, 1986; Olsen, 1987; Amagloh and Benang, 2009; Arantes et al, 2012). When the seed powder is added to the cloudy water, the proteins release positive charges by attracting the negatively charged particles such as clay, bacteria, and other toxic particles present in water forming flakes and aggregating the particles present in the water (Santos et al, 2009; Ferreira et al 2009)

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