Abstract:

Due to the lack of various biosynthetic pathways, lactic acid bacteria (LAB) are nutritionally fastidious and unable to synthesize some essential amino acids and vitamins. LAB possess extracellular proteinase and this enzyme hydrolyzes dairy casein into oligopeptides and amino acids, which can be transported into cells by the oligopeptide transport system (Opp) and the di-tripeptide transport systems (DtpT and DtpP), followed by the hydrolysis of intracellular oligopeptides by endogenous peptidases into free amino acids supporting the synthesis and metabolism of LAB cells during their growth. Hence, studies of protein metabolism in lactic acid bacteria have great significance for improving LAB growth, establishing high-density culture systems and promoting the formation of flavor compounds and their precursors during the fermentation of cheese and other dairy products.

Key words: lactic acid bacteria, protein, metabolism