Streptococcus thermophilus의 자연적 형질전환 메커니즘과 Leuconostoc 속 세균에서 그 메커니즘의 추론

Natural genetic transformation is one of mechanism for horizontal transfer of genetic elements in bacteria which is an integral part of the physiology of bacteria. Streptococcus thermophilus utilize a novel quorum sensing system to control for development of natural competence which composes Rgg-type response regulator (ComR) and hydrophobic peptide pheromone (ComS). Matured ComS is released outside of cell during early exponential phase when growing in peptide free chemical defined medium (CDM). Matured ComS is transported via Ami (oligopeptide transport system) form outside to cytoplasm, and then bind to ComR. Activated ComR (matured ComS combining form of ComR) induces transcription of comX, which encodes an alternative sigma factor (σ^x) that regulates expression of late competence genes. Adding synthetic matured form of ComS to CDM, it can induce genetic transformation of S. thermophilus. The genus Leuconostoc has not been identified natural transformation mechanism even though presenting homologous genes related with late competence development. The study for identifying natural transformation mechanism of Leuconostoc can realize development of improved strains for kimchi industry.