Comparative studies of lipoteichoic acids from several Bacillus strains

Area of Science:

• Microbiology
• Biochemistry
• Structural Biology

Background:

• Lipoteichoic acids (LTAs) are essential cell wall components in Gram-positive bacteria, influencing cell adhesion and antibiotic resistance.
• Structural heterogeneity of LTAs can impact bacterial physiology and interactions with the host environment.

Purpose of the Study:

• To elucidate the structural variations in lipoteichoic acids from ten different Bacillus strains.
• To characterize the linkage between polymer chains and lipid anchors in distinct LTA chemotypes.

Main Methods:

• Lipoteichoic acids were extracted from defatted Bacillus cells using phenol-water partition.
• Purification was achieved through chromatography on DEAE-Sephacel and Octyl-Sepharose columns.
• Structural analysis involved hydrogen fluoride treatment and Smith degradation.

Main Results:

• Two distinct groups of LTAs were identified based on their composition and structure.
• Group A LTAs (Bacillus subtilis, Bacillus licheniformis, Bacillus pumilus) contained D-alanine, D-glucose, and D-glucosamine, with polymer chains linked via gentiobiose to acylglycerol anchors.
• Group B LTAs (Bacillus coagulans, Bacillus megaterium) contained D-galactose, with galactosylated poly(glycerolphosphate) chains directly linked to acylglycerol anchors.

Conclusions:

• Bacillus strains exhibit distinct lipoteichoic acid structures, classified into two main chemotypes based on glycosyl linkage to lipid anchors.
• These structural differences in lipoteichoic acids may contribute to variations in cell wall properties and bacterial behavior among Bacillus species.