Autolytic defective mutant of Streptococcus faecalis.

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Cellular autolysis is crucial for bacterial cell wall remodeling.
• Antibiotics targeting cell wall biosynthesis can reveal insights into autolytic processes.
• Streptococcus faecalis is a significant human pathogen.

Purpose of the Study:

• To characterize a mutant of Streptococcus faecalis ATCC 9790 with defective cellular autolysis.
• To investigate the properties of the autolytic enzyme in the mutant strain.
• To determine the basis for altered autolysis in the mutant.

Main Methods:

• Selection of a mutant strain from a mutagenized population exposed to penicillin G and cycloserine.
• Analysis of cellular autolysis patterns and autolytic enzyme activity.
• Enzymatic assays using isolated autolysin and cell wall substrates from S. faecalis and Micrococcus lysodeikticus.

Main Results:

• The mutant strain displayed a thermosensitive autolysis pattern.
• Autolytic enzyme activity in solution showed only slightly increased thermolability.
• The isolated autolysin exhibited altered substrate specificity, being inactive against Micrococcus lysodeikticus walls.

Conclusions:

• The mutant strain possesses an altered autolytic enzyme.
• This alteration affects the substrate specificity of the autolysin.
• The findings suggest the synthesis of a modified autolytic enzyme in the mutant.