Effect of Chitosan on the Growth and Murein Hydrolase Activity of Streptococcus mutans with Mutations in the cid and lrg Two Component Autolytic Regulatory System

Chitosan is a naturally occurring polysaccharide with antimicrobial properties. This study investigated whether chitosan could induce the LytSR two-component autolytic regulatory system, specifically the cid and lrg operons, found in Streptococcus mutans. A turbidity assay and a murein hydrolase assay were used to observe autolytic activity in chitosan-treated and non-treated cultures of wildtype S. mutans, cidAB and lrgAB mutants, and E. coli. The turbidity assay showed that growth of all bacterial strains was inhibited and cell lyses occurred when cells were incubated in the presence of chitosan. Cultures treated with and without chitosan both showed decreased murein hydrolase production in the murein hydrolase assay.