Aim: To screen five strains of lactic acid bacteria (LAB) isolated from rye sourdoughs for the potential production of antimicrobial substances. Methods and Results: Lactobacillus sakei KTU05-06, Pediococcus acidilactici KTU05-7, Pediococcus pentosaceus KTU05-8, KTU05-9 and KTU05-10 isolated from rye sourdoughs were investigated for the production of bacteriocin-like inhibitory substances (BLIS). The supernatants of analysed LAB inhibited growth of up to 15 out of 25 indicator bacteria strains as well as up to 25 out of 56 LAB strains isolated from rye sourdoughs. Moreover, these five LAB were active against ropes-producing Bacillus subtilis and the main bread mould spoilage causing fungi -Aspergillus, Fusarium, Mucor and Penicillium. Lactobacillus sakei KTU05-6 demonstrated the best antibacterial properties and is resistant towards heat treatment even at 100 degrees C for 60 min. Conclusions: The use of LAB-producing antibacterial substances may be a good choice as a co-starter culture to ensure the stability of sourdoughs and to avoid the bacterial and fungi spoilage of the end product. Significance and Impact of the Study: The antimicrobial compounds designated as sakacin KTU05-6, pediocin KTU05-8 KTU05-9, KTU05-10 and AcKTU05-67 were not identical to any other known BLIS, and this finding leads up to the assumption that they might be the novel.