Jing-Ren Zhang
  • Center for Infectious Disease Research, School of Medicine, Tsinghua University, China
研究方向
  • Microbiology
Observation of Pneumococcal Phase Variation in Colony Morphology
肺炎球菌菌落形态学相位变异的观察
作者:Jing Li, Juanjuan Wang, Fangfang Jiao and Jing-Ren Zhang日期:08/05/2017,浏览量:9011,Q&A: 0
Streptococcus pneumoniae (pneumococcus) is an important human pathogen that causes pneumonia, meningitis, sepsis, and otitis media. This bacterium normally resides in the nasopharynx as a commensal, but sometimes disseminates to sterile sites of humans and causes local or systemic inflammation. This biphasic behavior of S. pneumoniae is correlated with a reversible switch between the opaque and transparent colony forms on agar plates, a phenomenon referred to as phase variation. The opaque variants appear to be more virulent in animal models of bacteremia but are deficient in nasopharyngeal colonization animal models. In contrast, the transparent variants display higher levels of nasopharyngeal colonization but relatively lower virulence in animal models. We have recently demonstrated that pneumococcal phase variation between these two colony types is caused by a reversible switch of genome DNA methylation (or epigenetic) patterns, which is driven by DNA inversions in the DNA methyltransferase genes. Observation of colony morphology is a simple and useful method to differentiate colonies with different characteristics, such as size, color, and opacity. This protocol describes how to study pneumococcal phase variation in colony morphology with a dissection microscope.