Microbiology Research Journal International

In vitro Antibacterial Activity of Mulberry Fruit Extracts from Different Accessions against Salmonella enterica and Bacillus cereus

R. Moulidharshan — 2025-09-11

The emergence of antibiotic-resistant foodborne pathogens, particularly Salmonella enterica and Bacillus cereus, highlights the necessity for efficient natural antibacterial alternatives. The present study evaluated the in vitro antibacterial efficacy of aqueous fruit extracts from five mulberry (Morus spp.) accessions (MI-0789, MI-0632, MI-0489, MI-0300 and MI-0783) against these pathogens. Extracts were evaluated at doses ranging from 20 to 100 µL utilizing the agar well diffusion method, with inhibition zones recorded following 24- hour incubation at 37 °C. The results demonstrated significant changes in antibacterial activity that were depending on genotype and concentration. MI-0300 demonstrated enhanced efficacy against both Salmonella enterica (25 mm at100 µL) and Bacillus cereus (38 mm at 100 µL), exhibiting significant activity even at reduced dosages. MI-0783 and MI-0789 exhibited moderate activity, but MI-0632 and MI-0489 shown weak or negligible inhibition. The observed differences are due to variances in phytochemical composition, specifically phenolics, flavonoids and anthocyanins. These findings underscore MI-0300 as a potential candidate for the development of natural antibacterial agents, functional foods and nutraceutical products.

Evaluation of the Antibacterial Activity of Clove Extract (Syzygium aromaticum) on Clinical Isolates of Staphylococcus aureus

Lynda Kadi Giami — 2025-09-16

Antibiotic resistance to conventional antibiotics has remained a significant therapeutic challenge in clinical settings. To this end, alternative therapeutic approaches are being sought after. One such approach is the use of antimicrobial inhibitors derived from natural sources, such as medicinal plants. S. aromaticum contains phenylpropene eugenol, which gives it its strong characteristic aroma. This component also demonstrates broad antimicrobial activity against Gram-positive, Gram-negative, and Acid-fast bacteria, as well as antifungal properties. Flavonoids in S. aromaticum contribute to various cellular defence mechanisms, acting against different inflammatory mediators and free radical species. This study aimed to explore the antibacterial potential of aqueous and ethanolic extracts of Clove (Syzygium aromaticum) against Staphylococcus aureus isolated from clinical sources in Port Harcourt, Nigeria. The antibacterial activity of S. aromaticum extracts against S. aureus was determined in vitro in aqueous and ethanolic extracts at four different extract concentrations: 200mg/ml, 100mg/ml, 50mg/ml, 25mg/ml and 12.5mg/ml. Analysis of phytoconstituents revealed the presence of Flavonoid, Saponins, Alkaloids and Eugenol. The aqueous and ethanolic extracts revealed a significant degree of antibacterial activity against S. aureus isolates at concentrations of 200mg/ml with zones of inhibition of 24mm and 28mm, respectively. Minimum Inhibitory Concentration (MIC) for the aqueous and ethanolic extract was at a concentration of 200mg/ml, and the Minimum Bactericidal Concentration (MBC) for aqueous and ethanolic extract was also at a concentration of 200 mg/ml. Antibiotic susceptibility testing revealed that S. aureus was susceptible to Ciprofloxacin. The independent T-test analysis revealed no significant difference in the diameter of the inhibition zone between the aqueous and ethanolic extracts of cloves (P = 0.640). Notably, the antibacterial activity of S. aromaticum extract was comparable to that of Ciprofloxacin because the zone of inhibition was at par with those observed with the ethanolic extract. This study suggests that S. aromaticum extract may be a promising natural antibacterial agent for combating S. aureus infections at high concentrations. Based on the results, further research is recommended using even higher concentrations of the extract and various extract media such as methanol, chloroform, and acetone to observe and compare their inhibitory effects on S. aureus.

Prevalence and Multidrug Resistance of Vibrio furnissii in Hand-Dug Wells Near Septic Tanks in Two Suburban Lagos, Nigeria

Tayo Modupe Kayode-Isola — 2025-09-17

Access to safe drinking water is key to achieving appreciable gain in human health, which is a focus of the sustainable development goals (SDGs) and One health; hence well water meant for consumption must meet the quality guidelines for drinking water to reduce possible health-risk associated with chemical hazard and pathogenic microorganisms such as Vibrio species. Water samples from thirty hand-dug wells sited close to septic tanks in Ojo and Badagry areas of Lagos, Nigeria were examined for the prevalence of Vibrio species using membrane filtration techniques on Thiosulfate-Citrate-Bile-Salt Sucrose (TCBS) agar after enrichment in Alkaline Peptone Water, and the Vibrio isolates were evaluated for multidrug resistance using disc diffusion method and their plasmid profile assayed. A total of one hundred and thirty-one (131) strains belonging to five (5) species of Vibrio were obtained. Vibrio furnissii strains (58;44.3%) were the most prevalent, they were found in twenty-three (23) of the wells. Other Vibrio species isolated were Vibrio vulnificus (24;18.3%), Vibrio harveyi (15;11.5%), Vibrio anguillarum (12;9.2%), Vibrio parahaemolyticus (6;4.6%), Vibrio mimicus (12;9.2%) Vibrio cholera (4;3.1%). Vibrio. anguillarum and Vibrio. parahaemolyticus were found in only one well each. Thirty-two (55.17%) of the Vibrio furnissii were resistant to three or more classes of antibiotics (multi-drug resistant – penicillin, cephalosporin, chloramphenicol, cotrimoxazole). Eleven (34.4%) of multi-drug resistant Vibrio furnissii possessed plasmid with molecular weight varying between 690 kbp and 974 kbp. Contamination of the studied well water by species of Vibrio is clearly evident, this can be linked to the generally unhygienic state of the catchments of the wells. Also, detection of multidrug resistance in Vibrio furnissii portend possible difficulty in managing infection that may result. This requires urgent intervention; especially point of use interventions such as use of hypochlorite or boiling, to ensure the communities have access to safe drinking water.

Phytochemical Profiling and Anti-MRSA Activity of Extracts from Moringa oleifera Lam. and Senna occidentalis (L.) Link Cultivated under Organic Conditions

Koné Souleymane — 2025-09-24

The emergence of antibiotic-resistant bacterial strains, particularly Methicillin-Resistant Staphylococcus aureus (MRSA), is a major threat to global public health. In this context, medicinal plants represent a promising alternative for the discovery of new antimicrobial agents. The aim of this study was to explore the phytochemical profile and assess the antibacterial activity of extracts in solvents of different polarity from Moringa oleifera (leaves, stem bark, flowers) and Senna occidentalis (leaves, stem bark, seeds, pods) against clinical strains, including 10 MRSA strains, 4 methicillin-sensitive Staphylococcus aureus (MSSA) strains, and an ATCC 25923 strain for quality control. The extracts were obtained by maceration in water, ethanol (70 %) and dichloromethane, followed by concentration in a rotary evaporator. Phytochemical screening was carried out using conventional chemical reactions in a tube, enabling the presence of secondary metabolites such as flavonoids, tannins, alkaloids, saponins, sterols, triterpenes, anthocyanosides, coumarins and reducing compounds to be identified. Assessment of the antimicrobial activity, using disk diffusion and broth dilution methods, revealed that M. oleifera flower extract exhibited marked antibacterial activity, with an inhibition zone of more than 10 mm and a bactericidal effect with a MBC/MIC ratio ≤ 4. In comparison, S. occidentalis showed more modest activity. These results suggest that M. oleifera extracts could be an effective natural alternative in the treatment of infections caused by resistant strains of staphylococci.

Assessment of Pollution and Its Associated Risks to Public Health in the Camaron-Sabalo Lagoon, Mazatlan, Mexico

Jose Guilermo Galindo Reyes — 2025-09-27

The Camaron-Sabalo Lagoon is a body water located within of Mazatlán city, NW Mexico. The lagoon's surface area has been significantly reduced by the construction of hotels, boulevards, and the expansion of the aquarium; it also receives illegally wastewater from surrounding quarters. It has result in environmental impact and water pollution of the lagoon, which improve the mosquito’s growth and pathogenic bacteria; consequently, in a public health risk for residents and tourists. Therefore, the aim this work was to know the coliform bacteria levels and Dengue and Chikungunya cases, by the water pollution. Along one year, water and mosquitoes’ samples were taken each three months. The amount of coliform bacteria was quantified by the dilution multiple tubes method; whereas the mosquitoes were captured using an entomological net. The identification and quantification were performing by optical microscopy and the entomologic handbooks of the School National of Biological Sciences and Science Faculty of UNAM. The Dengue and Chikungunya cases were obtained from the Mexican Health Ministry. The results indicate that the highest number of coliform bacteria and mosquitoes were recorded during the rainy months (July, August, and September); also, the higher dengue and chikungunya cases, also occurred during these months. This is because during the rainy season, the amount of contaminated water draining to lagoon, increases, exceeding the capacity of the lagoon basin. Therefore, it is possible to conclude that environmental impact caused by construction of hotels and other facilities to enhance tourism, has contributed to increase pollution and public health risks, due the higher proliferation of mosquitoes and fecal coliform bacteria.

Antiradical, Antioxydant and Antimicrobial Properties of Essential Oil of Eucalyptus tereticornis Used in the Treatment of Respiratory Diseases in Togo: A Phytochemical Study Approach

KPATSIDE Abla Ahoéfa — 2025-09-28

Introduction: Traditional medicine has seen a resurgence of attention and interest worldwide. Eucalyptus tereticornis is a medicinal plant belonging to the Myrtaceae family. This study was initiated to assess the therapeutic potential of Eucalyptus tereticornis essential oil.

Methods: The essential oil was obtained by steam distillation and analyzed by GC/MS. Refractive index was assessed in accordance with ISO 280 (1998). Antiradical activity was assessed by the DPPH free radical scavenging method, while antioxidant activity was assessed by the FRAP test. Antimicrobial activity was assessed using the plate microdilution method coupled with nutrient agar spreading.

Results: Essential oil yield was 0.75%. The refractive index was 1.475 ± 0.004. Thirty-three compounds, representing 99.09% of the oil, were identified in the EO. The major constituents are α-Pinene (55.72%), β-Pinene (16.73%), O-Cymene (7.40%), Eucalyptol (5.45%), β- terpineol acetate (2.69%) and Aromadendrene (1.99%). Anti-free radical activity was estimated at 4.11 ± 0.01 µg EAA/g EO and antioxidant activity at 0.60 ± 0.11 mg EAA/g EO. The antimicrobial activity results show that Eucalyptus tereticornis essential oil has antibacterial activity against all the different micro-organisms selected.

Conclusion: The results of this study justify the traditional use of this plant against respiratory illnesses, and encourage research into new natural molecules with antioxidant and antibacterial properties, with a view to investing them in the pharmaceutical, cosmetics and food industries.

Evaluation of Antibacterial Effect of Bacteriocin Producing Lactic Acid Bacteria Isolated from Yoghurt and ‘Akamu’ on Selected Pathogenic Bacteria

Nzeako, Ijeoma Juliet — 2025-09-28

The rise of antibiotic resistance poses a significant threat to both human and animal health. As resistance to standard antibiotics becomes more prevalent, the need to discover new sources of effective Antimicrobial agent becomes inevitable. The study aimed to evaluate the antibacterial effect of bacteriocin-producing lactic acid bacteria isolated from yoghurt and ‘akamu’ on selected pathogenic bacteria. Bacteriocin-producing lactic acid bacteria (LAB) are considered ‘Generally Recognised as Safe’ (GRAS) and useful to control the fast development of pathogens. In this study, a total of 30 “akamu” samples comprising maize, millet and guinea corn (separately) and 10 brands of yoghurt were analysed using standard microbiological methods. Lactobacillus fermentum and Lactococcus lactis were identified as major isolates from the samples. Antibacterial effect of these isolates was confirmed by agar well diffusion method on selected pathogenic bacteria: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis and Salmonella spp. The presence of zones of inhibition in mm shows the production of bacteriocins by LAB. The largest zone of inhibition, measuring 54 ± 2.82 mm, was observed with Lactobacillus fermentum against Pseudomonas aeruginosa, while the least zone of inhibition 11±0.707 mm, was observed with Lactococcus lactis against Escherichia coli using ciprofloxacin as a control. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) tests were also done to provide a more detailed quantitative and qualitative information on the potency and therapeutic potential of Lactobacillus fermentum and Lactococcus lactis. Isolation of bacteriocin-producing lactic acid bacteria from ‘akamu’ and yoghurt is a good strategy to curb antibiotic resistance and its effect. The findings from this study highlighted the potential of isolates from Akamu and yoghurt for producing antimicrobial compounds (Bacteriocin) and exhibiting antimicrobial properties. This study underscored the potential of lactic acid bacteria in preventing microbial infections, which significantly contributes to combating antimicrobial resistance (AMR). Thus, consumption of ‘akamu’ and yoghurt should be encouraged as they are of rich health benefits.