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Development of anti-AIV (Avian Influenza Virus) agents has been worldwide issues due to serious damage in poultry industries in Asia. The virus has expanded its geographical range to Europe and Africa. Recently, anti-viral study of lactic acid bacteria (LAB) from Kimchi has gained growing interest since the facts that, in a field test, ferments of Kimchi LAB were very effective against AIV is worldwide known. In the present study, cell-free supernatants from 9 strains of Kimchi LAB grown in MRS broth were tested to estimate their anti-viral activities against AIV. Among the strains tested, lactobacillus plantarum DC 412K showed the highest antiviral effects against AIV. Time-dependently, DC 412K cultured for three to five days exhibited 10-fold higher anti-AIV effects than that cultured for one to two days. The active components after 10 kd membrane filtration were found in a fraction higher than 10 kd; whereas anti-bacterial activity of
DC 412K broth is attributed to the low molecular mass fraction (< 3 kd) containing lactic acid as a major active component. It was observed that the anti-AIV components were very strongly adsorbed on anion exchange resins and thereby the eluted solutions didn’t exhibit the inhibitory effect. The anti-viral activity was still retained after both heating and 0.1% SDS treatment. Furthermore, its anti-viral activity always could be maintained at pH less than 4.5 but lost at pH 5.0-8.0 levels. The AIV activity of DC 412K was attributed to substances that behave similarly to negatively charged glycosaccharides because of the physicochemical properties. To further confirm the structural characteristics of the active components, sialic acid contents were determined by resorcinol assay method. The concentrated fraction using the 10 kd membrane filtration shows increased sialic acid contents as much as the increased anti-viral activities. Thus, the active components could be assumed to be sialyl-oligosaccharides. Consequently, it
was strongly expected that, from all of the results, lactobacillus plantarum DC 412K broth will be a good additive available for animal feed processing due to its high thermal stability and potent anti-AIV activity.