Antimicrobial and Phytochemical Screening of Water Melon (Citrillus lanatus) Seeds on Selected Bacterial species

Watermelon seeds are rich in protein, B vitamins, minerals (such as magnesium.  potassium, phosphorous, sodium, iron, zinc, manganese and copper) and fat among others, the antimicrobial compounds found in plants are of great interest because antibiotic-resistance is becoming a worldwide public health concern especially in terms of food-borne illness and hospital-acquired infections. This study investigates the antimicrobial and phytochemical attributes of watermelon (Citrillus lanatus) seed extracts against selected bacterial isolates. Ethanol and ethyl acetate were used as solvents to extract bioactive compounds from the seeds. The extract gotten were subjected for phytochemical screening and antimicrobial activity against the following microorganisms; Escherichia coli, Staphylococcus aureus, Salmonella typhi, Klebsiella pneumonia, and Pseudomonas aeruginosa. The result of phytochemical screening revealed the presence of flavonoids, tannins, phenols, alkaloids, glycosides, and saponins. Furthermore, the results of antibacterial activity showed that the ethanol extract exhibited significantly higher antimicrobial activity compared to the ethyl acetate extract, as shown by larger zones of inhibition and lower MIC and MBC values against the test organisms where Escherichia coli was the most susceptible organisms with a minimal inhibitory concentration at 50mg/ml zone of inhibition of 16.0 mm respectively. Similarly, ethyl acetate showed activity against the test isolates where Staphylococcus aureus emerged the most susceptible organisms with a minimal inhibitory concentration at 50mg/ml and zone of inhibition of 15.0 mm respectively. Klebsiella pneumonia, showed resistance to both extracts even at minimal inhibitory concentration above >250mg/ml.  using the agar well diffusion method, to determine their minimum inhibitory concentrations (MICs) and minimum bactericidal concentration (MBCs). However, ethyl acetate extracts contained fewer phytochemicals. These investigations support the practical application of watermelon seed extracts, especially ethanol-based, as a natural source of antimicrobial agents. It is also a prove to the growing body of research supporting the advancement of plant-based alternatives to synthetic antibiotics.