MICROORGANISMS

Dialium guineense fruit is an important tropical fruit which faces substantial post-harvest losses and food safety concerns due to microbial contamination. This study investigated microorganisms associated with the shell, pulp and seed of D. guineense to determine infection rates, identify microbial species (fungal and bacterial) and assess their diversity. The research was conducted at the media preparation room of the Department of Crop Science, Faculty of Agriculture, University of Benin, Benin City, Edo State, Nigeria. Three (3) fruit parts were studied: Shell, pulp and seed on Potato Dextrose Agar (PDA) and Nutrient Agar (NA) laid out in a Completely Randomized Design (CRD) with six (6) replications. It involved evaluating infection percentages, sub-culturing and identification based on cultural, morphological and biochemical characteristics. Results showed a 100% infection rate across all fruit parts except one (1) replicate which had a 75% infection rate, indicating significant microbial pressure. A wide variety of fungal and bacterial species was observed, with specific microbial adaptations per fruit part. Pathogenic bacteria, including Shigella sp. and Bacillus cereus, were identified, posing potential health risks, alongside Aspergillus and Fusarium species. This study confirms the fruit's vulnerability to widespread microbial contamination. Findings underscore the critical necessity for improved safety measures against Aspergillus and Fusarium contamination, while identifying promising opportunities to utilize Saccharomyces sp. for industrial processing and seed extracts for natural preservation

Analysis of microorganisms isolated from refrigerator surfaces and interiors is crucial for assessing the cleanliness and potential health risks associated with these appliances. Microorganisms that thrive in low temperatures (psychrophiles) can cause food spoilage and pose a health risk through foodborne diseases such as Listeriosis, Botulism, Salmonellosis, and Diarrhea. Therefore, it is essential to identify the types and concentrations of microorganisms present in different areas of refrigerators. This study aimed to evaluate the microbial quality of refrigerator exteriors and interiors in homes. Swabs and air samples were collected from 15 refrigerators in Ugbowo city and analyzed in a certified microbiology laboratory. Questionnaires were completed by refrigerator owners. Biochemical tests were used to further characterize the isolates. Antibiotic susceptibility testing was performed to determine the sensitivity or resistance of the identified isolates to various antibiotics. The results showed that the lowest microbial count was observed in refrigerators cleaned weekly (3.01 ± 0.41 CFU/ml), while the highest count was observed in refrigerators cleaned once a month (3.29 ± 0.33 CFU/ml). The lowest microbial count was observed in refrigerators with 5-9 hours of electricity supply (2.74 ± 0.20 CFU/ml), and the highest count was observed in refrigerators with 15-19 hours of electricity supply (3.56 ± 0.00 CFU/ml). The lowest microbial count was observed in refrigerators without external power supply (2.61 ± 0.79 CFU/ml), while the highest count was observed in refrigerators with external power supply (3.25± 0.31 CFU/ml). All identified isolates were 12 susceptible to gentamicin antibiotics, while they were all resistant to erythromycin, metronidazole, carbenicillin, and cefoperazole antibiotics. All identified microbial isolates except S. enterica were susceptible to iprofloxacin, and all identified microbial isolates except E. coli were resistant to tetracycline antibiotics. The Susceptibility Index suggests that E. coli is the most susceptible to the antibiotics used, with the lowest Susceptibility Index value of 0.5, while S. enterica is the most resistant and least susceptible, with the highest value of 0.75. Both are indicators of high-risk contamination sources, according to Davis and Brown (2016), with a value of ≥0.2 or higher being indicative of a "high-risk" contamination source. These results demonstrate the presence of various types of microorganisms in refrigerators. Domestic refrigerators may be considered as a significant potential source of foodborne illnesses. Therefore, it is imperative to educate households, laboratories, and the general public about proper refrigeration practices. Regular (weekly) and thorough cleaning of refrigerators is essential to reduce the presence of microorganisms/microbial load

The research was carried out to evaluate the spoilage microorganisms of tomatoes sold in Benin City. Standard bacteriological methods were used to enumerate the total bacterial and fungal count of the tomatoes using pour plate methods after serial dilution. The bacterial isolates were characterized and identified using morphological and biochemical methods and sugar fermentation test. The percentage distribution and frequency of the isolates were evaluated using statistical method. The result obtained in this study showed that the highest bacterial, coliform and fungal population was obtained in Adolor sample with values of 6.07554±1.00, 5.09691±0.5 and 4.767155±0.5 log10 cfu/g respectively while the least bacterial, coliform and fungal count was obtained from Uselu and Ekosodin samples with values of 5.35218±2.00, 3.69897±1.00 and 4.32221±1.00 log10 cfu/g respectively. Using the cultural and morphological characteristics, the fungal isolates obtained in this study were Aspergillus niger, Trichoderma sp, Penicillium sp and Rhizopus arrhizus while the bacterial isolates obtained were Escherichia coli, Bacillus sp, Salmonella sp, Shigella sp, Klebsiella sp and Staphylococcus sp. From the result, isolates were resistance to many of the antibiotics including, collistin, Erytromycin, metronidazole and clindamycin but were susceptible to ciprofloxacin, augmentin and gentamycin. The result in this study has shed light into the gaining of entrance of food borne pathogens as well as some spoilage microorganisms (mostly fungi) during selling, harvesting and cultivation which may result in food poisoning.

The leaves of Persea americana have been discovered to exert antimicrobial properties. The upsurging need for new antimicrobial formulations has driven the quest to formulate and test the compatibility of formulation excipients and avocado extract. The aim of this study is to determine and compare the antimicrobial activity of the ethanol avocado leaf extract of Persea americana and its balm formulation. Fresh Persea americana leaves were harvested, dried, pulverized and macerated in ethanol for a week. Phytochemical screening was carried out on the extract, after which it was formulated into balms (0, 100, 200, and 400 mg/ml). The different balm concentrations were tested against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Klebsiella pneumoniae, and Pseudomonas aeruginosa, using the ditch plate method. Ciprofloxacin was used as the positive control, and statistical significance was determined using ANOVA, with a significance level of P≤ 0.05. The ethanol plant extract was found to contain alkaloids, saponins, phenolics, triterpenoids, and flavonoids. The extract with (0, 100 mg/ml) showed no activity on the tested organisms. The extracts at 200 and 400 mg/ml exhibited antimicrobial activity ranging from 19 – 27 mm with the 400 mg/ml extract showing greater activity against the tested organisms. The balm formulation exerted reduced antibacterial activity compared to crude extract. The balm formulation with (0, 100 mg/ml) showed no activity, while the 200 and 400 mg/ml showed lesser activity ranging from 8 – 20 mm. Conclusively, the antimicrobial activity of the ethanol extract of avocado leaves was influenced by the balm formulation. This indicates that the interactions and compatibility of formulation excipients are crucial factors to consider when formulating herbal products.