Kolekcija bakterija mlečne kiseline (BMK) je napravljena od mikroorganizama izolovanih iz fermentisanih mlečno-kiselinskih proizvoda dobijenih na tradicionalan način. Iz kolekcije 51 izolat je identifikovan kao Lactobacillus sp. Svi izolovani laktobacili pripadaju grupi mezofilnih sojeva koji dobro rastu na temperaturama od 15°C i 30°C, a ne rastu na temperaturi od 45°C. Testiranje sposobnosti rasta u prisustvu nizina pokazalo je da su izolati BGCGK4, BGHN40, BGBUK2-8, BGBUK2-7 i BGBUK2-16 rezistentni na bakteriocin nizin. U eksperimentu određivanja minimalne inhibitorne koncentracije (MIK) za nizin pokazano je da je najrezistentniji izolat Lactobacillus sp. BGCGK4. Izolat BGBUK2-16, determinisan kao Lactobacillus paracasei subsp. paracasei, produkuje bakteriocin označen kao Bac217 i pokazuje rezistenciju na 8000 IU/ml. Čišćenjem plazmida iz soja BGBUK2-16 dobijena su 2 derivata označena kao BGBUK2-16/K2 i BGBUK2-16/K4. Derivat BGBUK2-16/K2 zadržao je rezistenciju na Bac217 i nizin, ali je izgubio sposobnost sinteze Bac217, dok je derivat BGBUK2-16/K4 pored gubitka sposobnosti sinteze Bac217 postao senzitivan na Bac217 i nizin. Prirodno rezistentni laktobacili se mogu iskoristiti za pripremanje starter kultura u kombinaciji sa nizinom kao konzervansom u cilju kontrolisane mlečno-kiselinske fermentacije.The collection of lactic acid bacteria (LAB) was made by isolation of microorganisms from fermented products traditionally manufactured in different geographical regions (high mountains, river valleys, seaside, etc). Among collected LAB, 51 isolates were identified as Lactobacillus sp. Results showed that all isolated lactobacilli were mesophilic strains, since they grew at 15°C and 30°C but not at 45°C. Testing the ability of isolated lactobacilli to grow in the presence of nisin revealed that Lactobacillus sp. isolates designed BGCGK4, BGHN40, BGBUK2-8, BGBUK2-7 and BGBUK2-16 were resistant to nisin. Determination of the minimal inhibitory concentrations (MIC) for nisin revealed that the most resistant isolate was Lactobacillus sp. BGCGK4. Isolate BGBUK2-16, determined as Lactobacillus paracasei subsp. paracasei, produces bacteriocin, named Bac217 and showed a resistance to 8000 IU/ml of nisin. Plasmid curing of BGBUK2-16 resulted in derivatives BGBUK2-16/K2 and BGBUK2-16/K4. Derivative BGBUK2-16/K2 retained resistance to Bac217 and nisin, but lost the ability to synthesise Bac217. Derivative BGBUK2-16/K4 lost concomitantly the resistance to both Bac217 and nisin
