Genetic regulation of Allolysis in response to antibiotic stress in Streptococcus pneumoniae

Abstract

Streptococcus pneumoniae is one of the major human pathogens that cause diseases like pneumonia, meningitis, otitis, acute conjunctivitis etc. Day by day the organism is acquiring resistance against many common antibiotics. One of the principal processes behind this is natural genetic transformation in the organism achieved by competence. Competence is a stress dependant mechanism in the bacteria. Another phenomenon that is induced by competence termed as allolysis is a peculiar process of the organism. In this process a group of cells which attain competence kill a group of cells that are non-competent. The mechanism involves bacteriocins, lysozymes and autolysins. This is believed to increase the efficiency of genetic transformation. But later it was assumed to have some other purposes like host pathogen interaction, pathogenecity and virulence and evolution of the species. In this study we tried to find out the effect of sub-lethal dose of antibiotic on allolysis. Chloramphenicol, the antibiotic against which the organism has developed resistance in the course of evolution was taken. The increase in eight fold in the expression of gene cbpD under stress condition showed that along with competence, allolysis also acts as a general stress response mechanism in the organism.