ANTIMICROBIAL ACTIVITY OF THREE MEDICINAL PLANTS AGAINST LISTERIA MONOCYTOGENES ISOLATED FROM BOVINE RAW MILK SOLD IN MAYA CITY, OROMIA REGIONAL STATE, EASTERN ETHIOPIA

Abstract

The misuse of conventional drugs in animals and food generated from animals were threatens both food safety and human health. So, the usage of medicinal plants of natural origin has been more alternatives recently. Experimental trial was conducted from November 2023 to June 2024 to evaluate the antimicrobial activity of three medicinal plants (separately and combined) by broth dilution method and determine reduction potential of these plant separately (not combined) in bovine milk during 6 hours, 12 hours, 18 hours of storage at 37oC against Listeria Monocytogenes isolated from the bovine raw milk Sold in Maya city, Eastern Ethiopia. The percentage yields obtained from the bulb of Onion, bulb of Garlic and rhizome of Ginger were 49.73% 43.18%, 22.95%, respectively. The qualitative phytochemical analysis showed the presence of saponin, tannins, alkaloids, glycosides and flavonoids but tannins and glycosides were absent in the onion. Garlic was shows the largest zone of inhibition from individual extracts (29 mm) .However, from all evaluated extracts combination of garlic with ginger shows the largest inhibition (36mm). The lowest MIC and MBC showed by combination of garlic with ginger was 1.95 mg/ml and 3.9 mg/ml respectively. For the reduction potential test, microbial load counted, and expressed in common logarithm considering concentration and time. The tested bacteria treated with garlic was reduced by 2.18 log10CFU/ml for 6hr, 3log10CFU/ml for 12hrs and 4.34log10CFU/ml for 18hr of holding time while kept at 37 oC storage. Garlic, at the studied concentration, has a significant reducing effect on tested bacteria compared to others. In conclusion, all tested plants had a potential effect against tested organism and insight plants to use them as an alternative of conventional drugs to reduce their negative side effects on human health. Thus, further study on food preservative activities of combined crude extracts and cytotoxicity level of each crude extracts must be analyzed.