Antifungal effect of lactic acid bacteria

Molds contaminated food and feedstuff, which are fundamental substances of human nutrition, not only can cause economic losses but also toxicity of the secondary compounds that molds can form, endanger the human health. For preventing that, the use of preservatives are common in the industry. In this study the antifungal effects of lactic acid bacteria, which are known as natural food preservatives, has been examined. Two strains of lactic acid bacteria (Lactobacillus plantarum I and II), Aspergillus niger ATCC 16404 and Penicillium roqueforti which has been isolated and identified at Uludağ Univercity Food Engineering Depratment, are used as material. Different concentrations of NaCl (0, 500, 1000 mg/L) and K-sorbate (0, 250, 500, 750, 1000 mg/L) impacts on moulds has been examined. Determination of antifungal effects of lactic acid bacteria with K-sorbate and NaCl has been practiced by using disc diffusion method. MRS Agar used as nutrient for stating antifungal action on moulds. Different concentrations of K-sorbat and NaCl have shown distinct inhibition effects on moulds. It is determined that inhibition rate of lactic acid bacteria is higher on P.roqueforti than A.niger. As K-sorbate concentration goes higher, it is found that hinderance quality of lactic acid bacteria elevated, on the other hand high amounts of NaCl caused low inhibition quality. At the 1000 mg/L K-Sorbat concentration, the antifungal effect of L.plantarum strains was found higher compared to lower concentrations of K-sorbate. As a result of that it is obtained that assayed concentrations of NaCl was not enough to suppress mould growth; preservatives and natural inhibition providers, such as lactic acid bacteria, and other spoilage preventing methods should be considered to combine together.