Proteomics analysis reveal that Moringa oleifera kills Escherichia coli by altering multiple biological processes

Every year 15 million babies are born prematurely worldwide and a million of these infants die. We know that bacterial infections are associated with and are the primary cause of preterm labor. Unfortunately, current antibiotic-based therapies are either unsafe or are becoming less effective due to the development of bacterial resistance to these therapies. Some of the key microbes associated with preterm labor include Gardnerella vaginalis, Lactobacillus spp., Atopobium vaginae, Mycoplasma hominis, Ureaplasma urealyticum and Escherichia coli (E. coli). Here, we investigated the effectiveness of different whole leaf Moringa oleifera (M. oleifera) extracts and subsequently the sub-fractions of ethanolic whole leaf extract to inhibit growth of and/or lysis E. coli, and compared the most potent leaf extract to common antibiotics. We also sought to determine the proteome-wide expression patterns of the bacterium when incubated with whole leaf M. oleifera extract using quantitative proteomics. From these studies, we demonstrate that: (1) ethanolic whole leaf M. oleifera extract causes the greatest inhibition of E. coli and is comparable to inhibition observed by common antibiotics, (2) the 8 different phases of bacterial growth are prolonged or inhibited by extract treatment, (3) sub-fraction 5 exhibited the most potent inhibitory activities, followed by 8, and (4) proteomics analysis revealed that MO lyses E. coli by altering expression of multiple proteins involved in several biological processes of the bacteria, notably stress response, metabolism and energy maintenance.