Antibacterial activity assay The modified methods of Savadogo et al. (2004) and girum et al.(2005) were used to determine the antibacterial activities of the isolates . Five single isolated colonies were selected from MRS agar plates and transferred to grow in sterile MRS broth . The broth culture was incubated anaerobically at 35 for 24 h . After incubation, the culture was centrifuged at 10 000rpm for 20 min at 4 to obtain the culture supernatant .Un-inculated MRS broth was used as a control . The indicatormicroorganism (S.typhymurium ATCC 13311, L.monocytogenes ATCC 19115 , B.cereus ATCC 14579 and E.coli ATCC 25922 )were grown in Tryptone Soy broth (TSB) for 24 h at 35 .A Sterile cotton swab was dipped into the culture of the indicator microorganisms and rotated several times, and the swab was then pressed firmly on the inside wall of the tube above the fluid level to remove excess inoculums . The dried surface of Mueller - Hinton agar (MHA) WAS INOCULATED BY STREAKING THE SWAB over the entire agar surface . This procedure was repeated by streaking two or more times while rotating the plate each time to ensure an even distribution of inoculums .For the boassay , the sterile filter disc was dipped into the culture supernatant and touched to the side of cantainer to remove excess liquid , and it was then plced on a MHA plate ( Branen et al., 1975 ).After 24 h of anaerobic incubation , each plate was evaluated , and the diameters of the inhibition zone ,including the diameter of the disc , were measured using a transparent ruler (Assefa et al. , 2008 ).
đang được dịch, vui lòng đợi..
