Fungi (mold) such as Penicillium, Mucor, Cladosporium, Meyerozyma, Candida and Rhodotorula frequently contaminate milk, cheese, and other dairy products. Spoilage fungi can come from many sources including air, surfaces, diary equipment, the cows themselves, and humans.
Lactobacillus are bacteria which often grow on human body surfaces such as the digestive and uro-genital tracts and are generally considered to be helpful bacteria. Other probiotic bacteria such as Bifidobacterium and Pediococcus may also have significant antifungal activity.
A Czech Republic/ German study tested 112 strains of Lactobacillus and Pediococcus from dairy products and meats for their antifungal properties against mold species- Yarrowia lipolytica, Rhodotorula mucilaginosa, and Penicillium brevicompactum (1). Sixty-one % of the tested probiotic bacteria had at least some activity against at least one of the three fungi tested. None of the 23 Pediococcus strains tested had any significant anti-fungal activity. Of the 89 Lactobacillus strains tested, 3 showed strong anti-fungal activity against Yarrowia lipolytica, 23 showed antifungal activity against Rhodotorula mucilaginosa, and 43 showed antifungal activity against Penicillium brevicompactum.
Further testing with a yogurt model reported that two probiotic strains Lactobacillus paracasei SYR90 and Lactobacillus rhamnosus BIOIII28 had strong anti-fungal activities against two of the fungi Rhodotorula mucilaginosa and Penicillium brevicompactum but only minimal inhibition on Yarrowia lipolytica.
Future research may be able to determine what strains of Lactobacillus and other probiotic bacteria have the best antifungal properties when used in food products and/or used in human supplements.
References / Sources
1. Lacanin I, Mounier J, Pawtowski A, Duskova M, Kamenik J, Karpiskova R. Assessment of the antifungal activity of Lactobacillus and Pediococcus spp. for use as bioprotective cultures in dairy products. World journal of microbiology & biotechnology. 2017;33(10):188.