Antibacterial Activity of Lactic Acid Bacteria Isolated from Fermented Ethiopian Traditional Dairy Products against Food Spoilage and Pathogenic Bacterial Strains

Abstract

Fermented Ethiopian traditional dairy products containing LAB that show antibacterial activities against various food spoilage and pathogenic bacteria have been used for the preservation of fermented dairy products for a long time. However, there are no comprehensive scientific reports on the antibacterial activity of LAB isolated from various fermented dairy products in Pawe Woreda. The objective of the study was to evaluate the antibacterial activity of LAB isolated from traditionally fermented Ethiopian dairy products against spoilage and pathogenic bacteria. Thirty-five samples of fermented dairy products were collected from three cattle-farming areas of Pawe Woreda. A total of 97 LAB were isolated and screened primarily using the perpendicular streak plate method against 3 Gram-positive and 3 Gram-negative bacterial strains. Out of the 97 strains, 10 were active against at least two of the tested bacteria, of which 7 strains were selected for secondary screening by their broad-spectrum antibacterial activities. The seven in vitro antibacterial activities of the extract ranged from 5 to 16 mm in diameter during the secondary screening. In this study, Z2, Z4, and N2 strains exhibited the highest inhibition zone with broad-spectrum activity against all tested bacteria. The MIC and MBC values range from 0.10 to 0.30 µg/µL and 0.20 to 0.50 µg/µL, respectively. Following morphological, physiological, biochemical, and molecular characteristics, seven potent strains were identified as Lactobacillus acidophilus, Lactobacillus paracasei, Lactobacillus plantarum, Lactobacillus rhamnosus, Leuconostoc mesenteroides, Streptococcus thermophilus, and Lactococcus lactis. According to the findings of this study, Ethiopian fermented dairy products were the most potent source of bioactive compounds with potential effects against food spoilage and pathogenic bacterial strains.

The Bacterial Profile and Antimicrobial Susceptibility Patterns of Urinary Tract Infection Patients at Pawe General Hospital, Northwest Ethiopia

“…To prevent evaporation, the tube containing a standard solution was tightly sealed and stored at room temperature. Before comparing with the bacterial suspension, the turbidity standard tube was vigorously mixed by the vortex mixer which makes a uniform turbid appearance [ 10 ].…”

“…From an overnight culture, 3–5 morphologically identical bacterial colonies were suspended in 5 mL of normal saline (0.85%; 8.5g/L NaCl) vigorously mixed by the vortex mixer and comparing to that of 0.5 McFarland standards which are approximately equivalent to 1.5 × 10 8 CFU/mL. After adjusting the turbidity, a sterile cotton swab was dipped into the suspension and streaked over the entire surface of the prepared medium by rotating the plate in 60 o to ensure the even distribution of the inoculum [ 10 ].…”

Isolation and Characterization of Lactic Acid Bacteria from Fermented Milk Produced in Jimma Town, Southwest Ethiopia, and Evaluation of their Antimicrobial Activity against Selected Pathogenic Bacteria

“…The side effects of chemical preservatives that prevent growth of contaminants and extend the shelf life of food pose a challenge to modern food-processing technology. Thus, interest in “Green technology” representing a new ways of food processing and the use of microbial-derived metabolites as biopreservatives became an emerging technology [ 14 ]. Food preservation techniques are necessary to extend the shelf life of foodstuffs via killing or inactivating the contaminants and pathogens.…”

“…The use of antimicrobial metabolites/peptides to extend the shelf life of milk and milk products through antagonizing and killing food spoilage and pathogenic bacteria has given an interesting result worldwide [ 14 ]. Therefore, the main objective of this study was to isolate LAB from naturally fermented cow's milk (Ergo) and to evaluate their antimicrobial activity against selected bacterial pathogens that cause foodborne diseases.…”

Prevalence and Associated Risk Factors of Intestinal Parasites and Enteric Bacterial Infections among Selected Region Food Handlers of Ethiopia during 2014–2022: A Systematic Review and Meta-Analysis

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