Evaluation of the Antimicrobial Activities of Wollayta Honey against Escherichia coli O157:H7 and Salmonella Typhimurium and its Physico-Chemical Characteristics.

This study evaluated the antimicrobial activities and the physicochemical characteristics of five honey samples (White, Red, Yellow, Black, and Mixed) from Wollayta, Ethiopia. The agar dilution method was used to assess the antibacterial activities of honey against S.Typhimurium and E.coli strains. Microbial growth inhibition was determined by measuring the diameter of clear zone of microbial growth around the well in the agar. The mean inhibition zone diameters (mm) for White, Red, Yellow, Black and Mixed honey against S. Typhimurium and E.coli O157:H7 were 33.67 mm, 24.67 mm, 34.33 mm, 15.0 mm, and 27.0 mm; and 33.33mm, 31.33 mm, 23.67mm, 16.33 mm, and 26.67mm respectively. The minimal inhibitory concentration of White and Yellow honey samples against S.Typhimurium was 9.00 % (v/v) each, while for both Red and Mixed as well as for Black honey samples the values against the same pathogen were 10.00 % (v/v) and 11.00 % (v/v), respectively. In contrast, E.coli O157:H7 was inhibited at 7.0 % (v/v), 9.33 % (v/v), 8.67 % (v/v), 11.00 % (v/v) and 10.33 % (v/v) of White, Red, Yellow, black, and Mixed honey, respectively. The physicochemical properties of honey samples evaluated were pH, moisture, electrical conductivity, glucose, fructose, proline, and protein. The pH values of the honey samples ranged from 3.23 -6.61 and the highest value recorded was for Black honey (6.61 ±0.08).The mean moisture contents of White, Red, Yellow, Mixed and Black honey were 18.5%, 19.33%, 18.1667%, 18.33% and 17.67%., respectively. The EC values in the investigated honey samples varied in the range of 0.29 - 0.67mS/cm and were within the recommended range (lower than 0.8 mS/cm). The glucose content for all samples ranged from 34.33 - (37.67g/100g. The Yellow and Black honey showed the lowest mean value (34.33g/100g) while Red honey had the highest mean glucose content (37.67g/100g). The results obtained for glucose and fructose content of Wollayta honey is within the range required by international standards. The concentration of proline ranged between 778.33 and 1895g/100g while the total protein content ranged from 2.14 to 5.59 g/kg. The results of this study generally indicated that Wollayta honey has reasonably higher antibacterial activities and that its physicochemical characteristics are within the ranges determined forquality honey by international standards.