Research
Phytochemical Analysis and Antibacterial Activities of Citrullus Lanatus Seed against some Pathogenic Microorganisms
Aim: To evaluate the phytochemical components and antibacterial potentials of Citrullus lanatus. Materials and Methods: This was carried out by the crude extraction of the seeds with hot water, ethanol and methanol. The extracts were used to determine the presence of phytochemicals. Stock cultures of test organism such as Staphylococcus aereus, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, Proteus mirabilis and Streptococcus pyogenes were used to test the antibacterial effects of the extracts using the agar well diffusion method. Results: The extracts showed presence of antibacterial activities which were compared to antibacterial activity of a commercial antibiotic (Ciprofloxacin) against the test organisms. At 62.5mg, ethanol extract showed a weak inhibitory effect against Proteus mirabilis (3mm), Staphylococcus aureus (2mm) and Streptococcus pyogenes (2mm). Antibacterial activity of the extract was pronounced at higher concentrations (100, 500 and 250mg) for all the extracts. Hot and cold water extracts showed the presence of phenol and methanol extracts exhibited the highest bacterial activity. The phytochemical analysis showed the presence of phenol, saponin, tannin, flavonoid, alkaloid and cyanogenic glycoside. Conclusion: From this research, watermelon seeds when properly extracted and purified, acts as antibiotics which can be used in treatment of infections caused by pathogenic bacteria.
Effect of Varied Culture Conditions on Bacteriocin Production of Four Lactobacillus species Isolated from Locally Fermented Maize (Ogi)
Background: Lactic acid bacteria (LAB) predominates the micro flora of fermented products. They produce metabolites that inhibit the growth of food borne pathogens and spoilage microorganisms. Aim: To isolate and identify LAB species from fermented maize (Ogi) and to determine the effect of varied culture conditions on bacteriocin production and antibacterial activity against indicator organisms. Materials and methods: Four (4) isolates of bacteriocin producing lactobacillus species (L. lactis, L. fermentum, L. casei and L. plantarum) with antibacterial activity against Salmonella typhimurium (ATCC 14028) and Shigella dysenteriae (ATCC 23351) were subjected to varied growth medium conditions. Bacteriocin production was tested at different physical and cultural conditions such as temperature (25, 30, 35 and 400C), pH (5, 6, 7 and 8), sodium chloride (NaCl) concentration (2, 4, 6 and 8%) and incubation duration (12, 24, 48 and 72 hours). Results: The optimum bacteriocin production judged by their different zones of inhibition was recorded at temperature, 300C and then 350C. There were significant differences between all the incubation temperatures at P<0.05. Duration of incubation showed highest bacteriocin activity after 72 hours. Furthermore, optimal conditions for bacteriocin production were observed to be highest at pH 6.0 followed by 5.0 and then in 2% NaCl concentration. There were significant differences between the zones of inhibition of bacteriocins produced against the indicator organisms at various media pH and salt concentrations at P<0.05. Conclusion: These bacteriocins may have a potential use as food preservative and may help in improving the gastrointestinal tract by fighting off pathogenic bacteria.
