Microorganisms from starter and protective cultures - Occurrence of antibiotic resistance and conjugal transfer of tet genes in vitro and during food fermentation

This study analyzed antibiotic resistance and the occurrence of resistance genes in strains from starter and protective cultures. The largest number of obtained strains belonged to the genus Lactobacillus (n = 26; 44.9%), followed by Lactococcus (n = 17; 29.3%), Pediococcus (n = 8; 13.8%), Streptococcus (n = 4; 6.9%), Staphylococcus (n = 2; 3.4%) and Leuconostoc (n = 1; 1.7%). Among all strains, the highest Minimum Inhibitory Concentrations (MICs) were noted for tetracycline (max. >256 μg/ml), kanamycin (max. 48 μg/ml) and chloramphenicol (max. 32 μg/ml). The most common resistance genes were aph(3’)-IIIa (n = 35; 60.3%) and cat (n = 32; 55.2%). Strains derived from starter and protective cultures have the ability to horizontally transfer resistance genes in vitro and in situ. It should be noted that antibiotic resistance of bacteria from starter and protective cultures does not present an immediate risk to consumers. However, these microorganisms could become an environmental reservoir of antibiotic resistance. The obtained results indicate that antibiotic resistance in starter and protective cultures is not a critical issue, however it creates a concern that cannot be ignored.