Studies on Molecular Biology of Dairy Starter Cultures : Studies on Molecular Biology and Biotechnology of Propionibacteria and Lactic Acid Bacteria in Dairying

Spoilage of milk and its products is regular in hot climate countries. Investigations were performed concerning additives use against the harmful microorganisms including Bacillus and Clostridium. The former spoils liquid milk, whereas the latter spoils cheese during storage. Both are pathogens and spore - formers distributed in heat treated milk products. Propionicin T1 was discovered among propionibacterial bacteriocins. It has a bactericidal effect against Bacillus and Clostridium. pctA gene of Propionibacterium thoenii 419 expressing propionicin T1 was isolated using specific PCR technique and cloned via pLEB590 (cloning vector) and pINT125 (integration vector) to some lactic acid bacterial strains. Such modified strains could be used as dual-purpose dairy cultures that produce propionicin T1 to inhibit spore-formers beside its basic rule to produce healthy dairy products with extended shelf-life.