Evaluation of the antimicrobial activity of Moringa oleifera seed extract as a sustainable solution for potable water

Pathogen contamination in drinking water sources is of great concern, particularly for communities with limited resources across the globe. At the same time, there is a pressing need to develop water treatment solutions which are sustainable and are 'green'. To address this issue, we have provided a detailed antimicrobial study of the seed extract of Moringa oleifera, which is a common medicinal plant found all over southeast Asia and Africa. In this study we report the efficacy of the extract in inhibiting bacterial growth on agar and in nutrient medium (lauryl tryptose broth) and the role of different parameters of bacteria concentration and extract concentration on its antimicrobial activity. This study further involves the determination of the decay rates of a Gram-negative (Escherichia coli) and a Gram-positive (Bacillus subtilis) bacteria in 100 mL of non-turbid water in the presence of 2, 3, 5 and 10 mL of the seed extract. The seed extract volume of 10 mL led to a maximum bacterial decay of 93.2% for E. coli and 96.2% for B. subtilis. The bacterial decay data were fitted to exponential curves and three different regimes of decay were observed over a period of 6 h. B. subtilis showed 35% re-growth during the third regime compared to the initial test concentration, which can be attributed to the resistance created by the modification of the peptidoglycan backbone of the cell wall.