Effets des extraits de deux espèces de Moringa Adans, 1763 sur quelques microorganismes aquatiques d’importance clinique

Abstract

The presence of pathogenic microorganisms in drinking water is responsible for certain diseases such as gastroenteritis, cholera and typhoid fever. The use of plant extracts is an alternative method to chemical and physical treatment of water. The objective of this study is to evaluate the antimicrobial activity of extracts from the organs of Moringa oleifera and Moringa stenopetalaorgans extracts and characterize the molecules that may be responsible. Physiological solutions, containing planktonic microorganisms (Escherichia coli, Staphylococcus aureus, Salmonella typhi, Aeromonas hydrophila, Candida albicans and Candida parapsilosis) and incubated between 3 to 24 hours; at temperatures 7 to 44 ° C and light intensities between 0 and 3000 lux, were treated with different concentrations of extracts (0.5 to 2 g / L) of Moringa. The phytochemical profile from aqueous and ethanolic extracts revealed 11 compounds, the most abundant of which were alkaloids, flavonoids and phenols. In Moringa stenopetala, cell abundances are obtained with alcohol maceration extracts (EMA) of the bark of the stems, water decoction extracts (EDE) of the leaves, water decoction extracts of the bark of roots and extracts of water maceration (EME) of the bark of the stems, respectively on the bacteria S. aureus, E. coli, S. typhi, A. hydrophila. On the other hand, with the fungi C. albicans and C. parasilosis, cellular inhibitions were obtained after treatment with each of the 3 types of extracts from the bark leaves of stems and roots. Regardless of the type of microorganisms, cell abundances generally result in total cell inhibition at extract concentrations of 1 to 2 g / L; after 9 or 24 hours of incubation and at temperatures 23, 37 or 44 ° C. In addition, the illumination of the cultures significantly reduced cell abundance, especially for S. aureus and the two yeasts (Candida albicans and Candida parapsilosis). They result in total inhibition at extract concentrations of 0.5 to 2 g/L. Pearson's correlation coefficient, in most cases, revealed an inversely proportional relationship between plant extracts and S. aureus (P ≤ 0.05) cells culture. For Candida albicans and Candida parapsilosis, these abundances decreased from 4.89 to 0 Log (CFU / 100mL); 5.11 to 0 Log (CFU / 100 mL), respectively. Thus, total inhibitions were observed with the three types of extracts with high light intensities. However, a significant difference was noted after 3 h at the threshold (P ≤ 0.05) which have Salmonella typhi in the ethanolic extract. With the yeasts Candida albicans, Candida parapsilosis; negative and significant correlations at the cut-off (P ≤0.01) were noted for all types of extracts and incubation times. The light thus plays a synergistic effect on the bacterium Salmonella typhi and the two yeasts Candida albicans and Candida parapsilosis in the presence of aqueous and ethanolic extracts of Moringa stenopetala. A hierarchy of the various factors considered that can influence the growth of cells in the planktonic state showed that the incubation time is the most influencing parameter, then the concentration of the extract followed by the temperature and the light intensity. Chromatographic analyzes identified 176 and 149 molecules respectively in M. oleifera and M. stenopetala. Most of these molecules were flavonoids, alkaloids and phenols. Thus, 39.24 and 37.6% of these species were reveled to have antibacterial and antifungal activities. These activities resulted in the best minimum inhibitory concentrations (0.01 <MIC <0.009) on Escherichia coli and both fungi. The ratio of the MIC with the minimum bactericidal or fungicidal concentration showed that the activities on microorganisms are either bacteriostatic or fungistatic; either bactericidal or fungicidal These results show the potential use of extracts of M. oleifera and M. stenopetala in the microbiological treatment of water intended for human consumption.