CHAPTER 5 Discussion The current study reports on the antimicrobial of various M


The current study reports on the antimicrobial of various M. oleifera and M. stenopetala extracts, and on the effectiveness of Moringa seeds in water treatment. The ability of M. oleifera and M. stenopetala extracts to inhibit both Gram- negative and Gram-positive bacteria is in agreement with previous reports of the antimicrobial properties of these two species (Bukar et al,2010, Mekonnen,2003, Tesemma et al, Thilza et al, 2010, and Walter et al, 2011). The antimicrobial properties of Moringa species have been studied and has shown inhibitory ability against both Gram-negative and Gram-positive bacteria.
The current study shown Gram-negative bacteria to be more susceptible to M. oleifera and M. stenopetala ethanol extracts, than the Gram-positive bacteria tested. The ethanol extracts of M. oleifera and M. stenopetala shown the highest zone of inhibition the range of 13.1±0.1 mg/mL -17.1±1.3mg/mL against the three Gram-negative bacteria tested. The results obtained in this study showing greater susceptibility of Gram-negative bacteria to M. oleifera and M. stenopetala extracts is in contrast with certain previous studies conducted by Paz et al 1995, and kudi et al 1999 that has shown greater susceptibility of Gram-positive bacteria to some African and Nigerian medicinal plants. However, The greater susceptibility of Gram-negative bacteria to M. oleifera and M. stenopetala extracts observed in this study is in agreement with the study conducted by Vesoul,J, and Cock, I (2011).
The M. oleifera and M. stenopetala extract components accountable for antimicrobial latent of these solvent extracts were not identified in the present study. Earlier studies have identified numerous bioactive compounds of these plants. Eilert et al (1981) identified 4?-4-rhamnousyloxy-benzyf-isothiocynate as an antimicrobial agent in M. oleifera. M. stenopetala seeds were reported to be dominated by isothiocyanates: benzyl isothiocyanate (54.30%) and isobutyl isothiocyanate (16.37%). (Nibret and Wink, 2010). The active agents in the extract of M. stenopetala responsible for the antibacterial property were found to be cholest-5-en-3-ol, palmitic acid, and oleic acid (Tesemma et al, 2013).
A study done by Bukar et al, (2010) that reported that S. aures was one of the microbes that was sensitive to Moringa extracts, and this correspond with the findings of this study as S. aures was inhibited by both M. oleifera and M. stenopetala extracts. S. aures is known to be resistant to a wide range of antibiotics. Most of the nosocomial S. aures infections are caused by methicillin- resistant S. aures (MRSA) strains. S. aures is also reported to be resistant to quinolines or multiresistant to other antibiotics leading to a limited choice for their control. Its methicillin resistant is caused by the acquisition of the mecA gene that encodes for a penicillin binding protein (PB2a) that has low affinity for ß- lactams. It is also reported that S. aures has caused a series of outbreaks in hospital and community that is reported to be resistant to all antibiotics tried against it though the mechanisms leading to epidemics of virulent disease are not fully understood. S. aures is known to produce an exopolysaccharide barrier that has an effect in limiting the action of drugs (Ortega et al, 2010). The results obtained in this study has shown that S. aures is susceptible to both M. oleifera and M. stenopetala extracts, though the mechanisms of action in destroying bacterial cell wall is not known or fully understood. M. oleifera and M. stenopetala extracts exhibited activity against S. sonnei. The microorganism E. coli, which is known to be multi-resistant to drugs was also inhibited by the plant extracts tested.
These results are of interest because this bacterium was cultured in aseptically environment. There is a need to study the mode of action of Moringa extracts in bacterial cell wall. Some bacteria are highly susceptibility to the extracts tested than to the drug/ antibiotic used as a positive control.
The results of antimicrobial studies of the water samples showed that there were some bacteria present in water before it was treated with Moringa coagulating agents. The seeds of M. oleifera and M. stenopetala have shown effectiveness in water treatment. The extract of Moringa seeds has shown both coagulating and antimicrobial properties, and these properties are safe for human health. The Moringa biosand filters analysed during this study have shown a combination of both biological and mechanical processes.

When the raw water is poured on the top of the filter, the organic material and dissolved solids are trapped on the surface of the fine sand. The sand filters have reduced the number of pathogens in raw water that were too numerous to count before dilution and this strongly agreed with the study by Barth et al, (1997). Both M. oleifera and M. stenopetala eliminated pseudomonas to zero cfu/mL.

The pH value of the raw water was 7.87. After the water was treated with Moringa powder; the pH decreased. This pH is in the range of the recommended pH for potable water. This shows that it was above the recommended limit. These organic compounds such as manganese ions were present in lower concentrations that are recommended for potable use. The total dissolved solid calculated from conductivity decrease from 556 mg/L to 36 mg/L for water samples treated with M. oleifera and from 556 mg/mL to 35 mg/mL for M. stenopetala.
Turbidity is defined as the cloudiness of water and it can be affected by the amount of total dissolved solid in water. The turbidity of raw water was 1.63 NTU. turbidity for the water treated with M. oleifera and M. stenopetala seeds powder tend to decreased with the amount of powder as presented in the data.

Studies by Francis and Amos (2009) documented that the action of Moringa as a coagulant lies in the presence of water soluble cationic proteins that is found in the seeds. These suggest that in water to be treated, the basic amino acids present in the protein of Moringa would accept a proton from water, and these lead to the release of a hydroxyl group that make the solution basic.


The data obtained express that the extracts of M. oleifera and M. stenopetala have great antimicrobial activity against S.aures, S.sonnei, S. macescens, E. fecalis, and E. coli. Thus, they can be used in the treatment of infectious diseases caused by resistant bacteria. Based on the results obtained it was concluded that M. oleifera and M. stenopetala can provide important benefits to the communities in which they are grown. The extracts could be promising natural antimicrobial agents with ability to control bacteria that cause water borne diseases. The extracts could be used as cheap and suitable method toward disease reduction thereby improving the quality of life of rural communities in developing countries. It can also be used to treat drinking water especially in developing countries. M. oleifera and M. stenopetala can be used to produce clean and safe drinking water easily using equipment that are inexpensive and fast. M. oleifera and M. stenopetala seeds can be used as coagulants to replace conventional coagulants, flocculants, hard water softener, and for removing heavy metals as well as turbidity in drinking water.


In order to improve the application of M. oleifera and M. stenopetala seeds in water treatments and as antimicrobial agents, the following areas need some further investigations;
1. Studies should focus on the mode of action of the extracts in destroying the bacterial cell walls.
2. The effects of the seeds extract shelf life on coagulation, disinfection and softening of water should be investigated.
3. Isolation of the exact active compound responsible for antimicrobial activity as well as water purification property.


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Calculations of TSS
TSS (mg/L) = (A-B) 1000/v
A= weight of dry filter paper plus dry residues, (mg)
B= Weight of dry filter paper, (mg)
V= Sample volume, mL
(a) Moringa oleifera
A= 1.231mg V= 1000 ml B= 1.225
TSS (mg/L) = (A-B) 1000/v
= (1.231-1.225)1000/1000
= 0.006 mg/ l
(b) Moringa stenopetala
A= 1.229mg V= 1000 mL B= 1.225
TSS (mg/L) = (A-B) 1000/v
= (1.229-1.225)1000/1000
= 0.004 mg/ L

(c) Raw water
A= 1.491mg V= 1000 mLB= 1.225
TSS (mg/l) = (A-B) 1000/v
= (1.491-1.225)1000/1000
= 0.226 mg/L