POSSIBILITY OF ENRICHMENT PROBIOTICS FOR RUMINANTS IN PLANT OILS FOR IMPROVING THEIR ACTIVITY AGAINS HARMFUL BACTERIA Summary

Among proposed alternatives to antibiotic growth promoters (AGPs), most effective in improving of efficiency of farming and having positive impact on animal welfare are probiotic preparations containing selected strains of lactic acid bacteria (LAB). It is known that essential oils exert ability to inhibit pathogenic bacteria. The aim of this study was to assess the pos-sibility of enrichment of probiotic preparations for animals in selected substances of vegetable origin, in order to increase the effectiveness of antimicrobial activity LAB directed against pathogenic microorganisms. The impact of three selected essential oils (thyme, sage and peppermint) on the capacity to growth, viability and antibacterial activity of probiotic or po-tentially probiotic strains of lactic acid bacteria (LAB) was evaluated. The assessment of the antibacterial activity of the LAB was conducted in relation to the bacteria strains pathogenic for animals (indicatory strains). The results show that the reaction of lactic acid bacteria strains for the presence of vegetable oils is very individual, depending on both the strain and the type of oil. All the tested plant’s oils inhibited the growth of strains of lactic acid bacteria. The minimum inhibitory con-centration of essential oils varied. In the case of peppermint oil and thyme oil LAB growth inhibition was observed at a con-centration of 0.1 % (v/v) and in relation to the sage oil this effect was found with 0.2 %.(v/v) average in medium. The viabil-ity of the tested LAB was observed in media containing higher concentrations up to several per cent of essential oils. In the presence of oils in concentrations affecting growth of LAB strains antimicrobial activity against pathogenic bacterial spe