Genetic Operation System of Lactic Acid Bacteria and Its Applications

Abstract

Lactic acid bacteria (LAB), a class of commonly existing microorganisms in nature, are important components of gut commensal microflora in humans and animals. Previous studies suggested that LAB exerted specific physiological and biochemical functions on the host such as improving intestinal microbial balance, immunomodulation, inhibiting tumor growth, lowering cholesterol levels, as well as regulating blood pressure and are therefore widely used in food manufacturing and functional food development. Due to the continuous development of modern molecular biology techniques, studies regarding exploiting LAB as expression hosts in addition to fermentation starter cultures and probiotics have received increasing attention from both academia and industry. In the 1980s, some researchers initiated molecular genetic research for LAB. They characterized lactose metabolism-related genes and proteins in LAB and established preliminary DNA delivery systems for LAB. Over the past decades, owing to the advances in modern DNA sequencing and gene characterization techniques, structures and functions of LAB genomes and plasmid-related genes have been further elucidated, which lays a solid theoretical foundation for the further development of LAB-based gene expression systems (Bolotin et al. 2001; Altermann et al. 2005).