ANTIMICROBIAL

This Research focused on the isolation and characterization of bacteriocin produced by Lactobacillus sp. isolated from nunu, a traditionally fermented milk beverage, and its antimicrobial effect against Escherichia coli. Samples of nunu were collected from local markets in Oredo Local Government Area, Edo State, and analyzed in the Department of Science Laboratory Technology Microbiology Laboratory. The isolate was cultured on de Man, Rogosa, and Sharpe (MRS) agar and identified through morphological and biochemical characterization. The isolates were Gram-positive, catalase-negative, and capable of fermenting lactose, galactose, and fructose, confirming them as Lactobacillus sp.. Bacteriocin production was screened using the agar well diffusion method, with E. coli as the test organism. Clear zones of inhibition (ZOI) were observed, indicating the production of antimicrobial compounds. The bacteriocin extract was neutralized to pH 7.41 to eliminate the effects of organic acids and partially purified using ammonium sulfate precipitation (60% saturation) followed by dialysis. The purified extract was further characterized using High- Performance Liquid Chromatography (HPLC), which revealed distinct peaks corresponding to bacteriocin fractions. The antimicrobial assay showed that the bacteriocin exhibited inhibitory activity against E. coli, suggesting its potential as a natural bio preservative in perishable food products such as tomato. The findings indicate that bacteriocin from Lactobacillus sp. in nunu can serve as safe and effective alternatives to chemical preservatives and synthetic antibiotics, thereby contributing to improved food safety and public health.

Lemongrass (Cymbopogon citratus) is widely known for its medicinal and antimicrobial properties, with its extracts being used in traditional and modern medicine. Due to the increasing resistance of bacteria to conventional antibiotics, plant-based antimicrobials have gained attention as alternative therapeutic agents. This study investigated the phytochemical composition and antibacterial activity of hot and cold water extracts of Lemongrass leaves against Staphylococcus aureus, Escherichia coli, and Pseudomonas sp. Phytochemical analysis revealed the presence of flavonoids, tannins, and glycosides in both extracts, with glycosides being more prominent in the hot extract. Saponins, steroids, and terpenoids were absent. Antibacterial activity was assessed using the agar well diffusion method, where the hot extract showed higher zones of inhibition at 100% concentration: S. aureus (13.00 ± 0.00 mm), E. coli (16.00 ± 0.00 mm), and Pseudomonas sp. (18.20 ± 0.00 mm), compared to the cold extract: S. aureus (9.0 ± 0.50 mm), E. coli (11.20 ± 0.20 mm), and Pseudomonas sp. (12.00 ± 0.00 mm). The Minimum Inhibitory Concentration (MIC) revealed that the hot extract inhibited E. coli at 25 mg/ml, Pseudomonas sp. at 50 mg/ml, and S. aureus at 25 mg/ml, while the cold extract only inhibited Pseudomonas sp. at 100 mg/ml and S. aureus at 25 mg/ml. Minimum Bactericidal Concentration (MBC) results showed that the hot extract was bactericidal against S. aureus and bacteriostatic against E. coli and Pseudomonas sp., while the cold extract was bactericidal against Pseudomonas sp. and bacteriostatic against the other isolates. Antibiotic susceptibility testing indicated that Gram-positive bacteria were highly susceptible to ciprofloxacin, while Gram-negative bacteria were sensitive to azithromycin. These results highlight the potential application of Cymbopogon citratus as an alternative treatment for bacterial infections, particularly in combating antibiotic-resistant pathogens.

Medicinal plants have long been recognized for their therapeutic properties and remain an essential source of bioactive compounds with potential antimicrobial activity. The growing problem of antibiotic resistance has heightened global interest in exploring natural plant extracts as alternative or complementary agents against infectious diseases. This study evaluated the phytochemical composition and antimicrobial potential of lemongrass (Cymbopogon citratus) and uziza leaf (Piper guineense) extracts against selected bacterial and fungal pathogens. Fresh leaves of both plants were collected from local markets in Benin City, Edo State, Nigeria, authenticated, air-dried, pulverized, and extracted using ethanol and water. Phytochemical screening revealed the presence of alkaloids, flavonoids, tannins, terpenoids, and saponins in varying concentrations. Lemongrass contained high levels of alkaloid, flavonoids and tannins, while uziza exhibited moderate presence of these compounds. Saponin was present in lemongrass but absent in uziza. Antimicrobial testing showed that ethanolic extracts demonstrated superior activity compared to aqueous extracts. The ethanolic extract of lemongrass exhibited the highest inhibition zone of 20 mm against S. aureus and 15 mm against E. coli at 100% concentration, while the uziza ethanolic extract produced inhibition zones of 18 mm and 15 mm, respectively, against the same organisms. Pseudomonas sp. showed moderate sensitivity with inhibition zones of 12 mm, whereas fungal isolates Aspergillus sp., Penicillium sp. and Fusarium sp. recorded inhibition zones ranging from 10 to 15 mm. The minimum inhibitory concentration (MIC) for ethanolic extracts ranged from 50 mg/mL for S. aureus, E. coli and Pseudomonas sp. to 100 mg/mL (for fungal isolates), while minimum bactericidal concentrations (MBCs) were observed at 100 mg/mL. Aqueous extracts displayed weaker activity, requiring higher concentrations (100 mg/mL) for inhibition and showing little or no effect on fungal isolates. Overall, these findings highlight the significant antimicrobial potential of lemongrass and uziza leaf extracts, particularly their ethanolic forms, which exhibited notable inhibitory effects against common bacterial pathogens. The results support their traditional medicinal use and underscore their potential as natural sources of plant-based antimicrobial agents.

This project was carried out to extract essential oil from the rhizome of Curcuma longa using the hydro-distillation method with a Clevenger apparatus. Curcuma longa is widely recognized for its medicinal uses, especially in India and other Asian cultures. The rhizomes are reported to contain essential oils with antimicrobial and antioxidant properties. However, while much attention has been given to the medicinal value of turmeric, comparatively less focus has been placed on the processes of extracting its essential oil and systematically evaluating their outcomes. In this study, dried rhizomes were ground into powder and hydro-distilled. The essential oil obtained was yellowish with a strong aromatic odor. The GC-MS analysis revealed a variety of compounds in the oil, with phenylbutazone (19.34%) and 6-theothiophylline (19.01%) being the most significant constituents, along with some other minor compounds. The antimicrobial efficacy of the oil was evaluated against selected pathogenic fungal and bacterial isolates. The curcuma longa extract stopped the growth of several fungi (Aspergillus Niger, Trichophyton rubrum, Penicillium sp.) and bacteria (Klebsiella pneumoniae and Staphylococcus aureus). However, it did not kill them at the tested concentration. Some microbes, like the bacteria Escherichia coli and Pseudomonas sp., and the fungus Aspergillus flavus, were not affected at all. Overall, this study shows that hydro-distillation method is a simple and effective method for obtaining turmeric essential oil at the laboratory scale. Characterizing its chemical profile and biological properties provides insight into its value and supports its potential applications in medicine, cosmetics, and food preservation. These findings validate the medicinal use of curcuma longa and highlight its potential as a source of natural antimicrobial agents. The oil shows particular promise for applications targeting both gram-positive and gram-negative bacteria and fungi. This study provides a foundation for the further development of curcuma longa based natural preservatives.

The growing global concern of antimicrobial resistance has fueled the hunt for alternative nanomaterials with therapeutic promise. This work used a green approach to create manganese– magnesium binary oxide (Mn–MgO) nanoparticles. Ficus exasperata leaf extract in alkaline environments (pH 9–10) act as a stabilizing and reducing agent. The nanoparticles' crystalline structure was validated by X-ray diffraction (XRD) examination, with distinctive peaks at 2θ values of 29.4°, 42.9°, and 62.0°, with an average crystallite size of 18 nm determined by the Debye–Scherrer equation. FTIR (Fourier Transform Infrared) spectrum showed notable peaks at 3339.69 cm⁻¹ (O–H stretching), 1543.11 cm⁻¹ (amide/aromatic C=C), and 1017.50 cm⁻¹ (C–O stretching), suggesting the existence of capping agents made of phytochemicals. Highly aggregated, irregular particles were found using scanning electron microscopy (SEM) that created a porous cluster structure. Energy Dispersive X-ray Spectroscopy (EDS) was used to verify the elemental composition; manganese (51.40 wt%), magnesium (35.00 wt%), and oxygen (5.20 wt%) were the primary elements. A primarily mesoporous structure was indicated by Brunauer–Emmett–Teller (BET) analysis, which showed a high specific surface area of 212.13 m²/g, a total pore volume of 0.106 cm³/g, and average pore diameters of 2.11 nm (BJH), 2.65 nm (DFT), and 3.04 nm (DA). A hybrid micro–mesoporous architecture was confirmed by the classification of the nitrogen adsorption–desorption isotherm as Type IV with an H3 hysteresis loop. There were no zones of inhibition (0 mm) against Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Aspergillus niger, and Candida albicans when antimicrobial activity was assessed using the agar well diffusion method at doses ranging from 7.813 to 62.5 mg/mL. As a result, values for minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC) were not determined. The Mn–MgO nanoparticles showed no discernible antibacterial activity despite having a large surface area and nanoscale crystallinity. This was probably caused by particle aggregation and surface passivation by phytochemical residues. These results demonstrate how important surface shape and accessibility are in influencing the bioactivity of green-synthesised nanoparticles.

The emergence of multi-drug resistant microbes has rekindled the interest on plant derived compounds as alternatives to existing antimicrobial agents.This study d et e rmi n e d the antimicrobial property of ethyl acetate extract of the fibrous stem of Bryophyllum pinnatum and phytochemical constituents of the fibrous stem. The ethyl acetate extract of the fibrous stem did not show any antimicrobial activity against the clinical fungal and bacterial isolates at 0.3g/mL concentration of the extract. Phytochemical analysis showed that alkaloids, flavonoids, terpenoids, tannins,saponins and glycoside which are responsible for antimicrobial activity were not detected. Gas Chromatography -Mass Spectroscopy also identified various phytocomponents. The ethyl acetate extract did not show anti-microbial activity.

Background: Oral hygiene is an important part of the body overall well-being, and should be treated with the utmost care to prevent dental problems. Acalypha wilkesiana Muell. Arg. Euphorbiaceae), commonly known as copper leaf, is a tropical lant native to West Africa, with notable antimicrobial activities. This study was carried out to investigate the antimicrobial properties of the methanol leaf extract of Acalypha wilkesiana formulated as herbal toothpaste. Method: Toothpaste was formulated using the leaf extract of A. wilkesiana. The extract was incorporated into a toothpaste base prepared using calcium carbonate, starch, glycerin, sodium lauryl sulfate, saccharine and peppermint oil. Sensory and physicochemical properties of the toothpaste were evaluated. Antimicrobial evaluation was by the Agar well diffusion method against Staphylococcus aureus, Escherichia coli, acillus subtilis, Pseudomonas aeruginosa, Klebsiella aerogenes, Candida albicans and Aspergillus niger at concentrations of 100-500
mg/ml. Results: The A. wilkesiana formulated toothpaste had a pleasant smell and was sweet to taste. It had good foaming abilities with a pH range of 7.4-7.8. The formulated herbal toothpaste had poor antibacterial activity but no antifungal activity against the clinical isolates at low concentrations. Significant activities were recorded at 500 mg/ml against all five (5) bacteria isolates, with Bacillus subtilis recording the highest zone of inhibition. Conclusion: The formulated A. wilkesiana toothpaste showed significant antibacterial effects against microbes implicated in periodontal diseases and dental caries, hence serving as a potential alternative to orthodox toothpastes for maintaining oral hygiene. Keywords: Acalypha wilkesiana, Euphorbiaceae, Antimicrobial, Toothpaste

The rising prevalence of multidrug-resistant uropathogenic Escherichia coli (UPEC) highlights the urgent need for alternative antimicrobial agents. This study aimed to evaluate the antibacterial activity, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-kill kinetics of ethanol and aqueous extracts of Hibiscus sabdariffa calyces against multidrug resistant UPEC isolates before and after plasmid curing. Antibacterial activity was determined using agar well diffusion, MIC and MBC by broth dilution, and time-kill assays by plate count method. The ethanol extract consistently showed stronger antibacterial activity than the aqueous extract, with lower MIC and MBC values and faster bacterial elimination in time-kill assays. Plasmid curing enhanced the susceptibility of UPEC to both extracts. Conclusively, Hibiscus sabdariffa, particularly the ethanol extract, demonstrated promising antibacterial potential against MDR UPEC, warranting further studies on dosage, and safety.

This study investigates the antimicrobial and antioxidant properties of ethanol and aqueous extracts of Curcuma longa (turmeric) rhizomes against clinical nasal isolates. The research aims to evaluate the efficacy of these extracts in combating microbial infections and their potential as natural antioxidants. The chemical composition of the extracts was characterized using Gas Chromatography-Mass Spectrometry (GC-MS), revealing a diverse array of bioactive compounds, including terpenes, fatty acids, phenolic compounds, and sterols. Antimicrobial activity was assessed using the broth dilution method, while antioxidant potential was determined through the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The results indicate that the ethanolic extract exhibited significant antimicrobial activity against nasal isolates, including Micrococcus species, Moraxella catarrhalis, and Streptococci species. Additionally, the aqueous extract demonstrated strong antioxidant properties, with a linear increase in activity correlating with concentration. The findings suggest that Curcuma longa extracts, particularly the ethanolic extract, hold promise as natural antimicrobial agents, while the aqueous extract shows potential as a potent antioxidant. This study underscores the therapeutic potential of Curcuma longa in addressing antibiotic resistance and oxidative stress-related conditions, providing a scientific basis for its traditional use in medicine and its application in modern healthcare

Antimicrobial resistance is a major global health problem that requires exploration for new natural drug alternatives. This study examines the extraction process, chemical analysis, and assessment of the antimicrobial properties of the volatile oils from Cymbopogon citratus and Ageratum conyzoides. Whole volatile oils were extracted from the two plants by hydrodistillation. The chemical constituents of both are compared by gas chromatography-mass spectrometry (GC-MS). Five bacterial and two fungal strains were chosen for the antimicrobial studies. The cup-plate agar diffusion method was used to test microbial susceptibility to the volatile oils. The oil yield of the two plants was 1.4% for C. citratus and 0.0079% for A. conyzoides. GC-MS analysis indicated that citral is the main ingredient of C. citratus, while A. conyzoides was high in precocene. C. citratus oil exhibited potent broad-spectrum antibacterial activity against in vitro-tested pathogenic bacteria and fungi in a dose-dependent concentration. With a potent antifungal activity. On the other hand, the essential oil of A. conyzoides showed weak performance and hence inhibited only P. aeruginosa and C. albicans at the highest concentration tested (25% w/v) and exhibited a weak effect against the other clinical isolates used in the study. C. citratus volatile oil demonstrated a very good antimicrobial activity and could serve as a good antimicrobial agent against bacterial and fungal infection