The present invention relates to novel strains of Propionibacterium as well as preparations and compositions, such as fermentation broths, protective cultures, final food or feed product with Propionibacterium alone or in combination with bacteria of the genus Lactobacillus. The present invention further relates to methods for the controlling of growth of a contaminant, such as a bacteria, yeast or mold by using these novel strains of Propionibacterium.