Degradation of bacterial lipopolysaccharide by the slime mould Physarum polycephalum

Area of Science:

• Microbiology
• Biochemistry
• Mycology

Background:

• Lipopolysaccharides (LPS) are crucial components of Gram-negative bacterial outer membranes.
• LPS can trigger potent inflammatory responses through its anticomplementary (AC) activity.
• The lipid A moiety of LPS is a primary determinant of its biological activity.

Purpose of the Study:

• To investigate the potential of the acellular slime mould Physarum polycephalum to degrade bacterial lipopolysaccharides (LPS).
• To determine which components of LPS are affected by Physarum polycephalum.
• To explore the enzymatic capabilities of Physarum polycephalum in breaking down LPS.

Main Methods:

• Incubation of various bacterial LPS with Physarum polycephalum cultures.
• Analysis of LPS degradation by measuring anticomplementary (AC) activity.
• Quantification of fatty acid content (lauric, myristic, palmitic, beta-hydroxymyristic acid) in LPS.
• Assessment of changes in immunodominant sugars and 2-keto-3-deoxy-D-manno-actanoic acid (KDO).
• Testing the LPS-degradative activity of Physarum supernates and plasmodial extracts on purified LPS and LPS within killed bacteria.

Main Results:

• Physarum polycephalum significantly degraded LPS from various bacteria.
• The anticomplementary (AC) activity of LPS was substantially reduced.
• Content of lauric, myristic, and palmitic acids in LPS decreased significantly.
• Physarum enzymes primarily targeted the lipid A moiety of LPS.
• Components like KDO, immunodominant sugars, and beta-hydroxymyristic acid were minimally affected.
• Both Physarum supernates and extracts demonstrated LPS-degradative activity.

Conclusions:

• Physarum polycephalum possesses enzymatic activity capable of degrading bacterial lipopolysaccharides (LPS).
• The degradation process specifically targets the lipid A component, reducing LPS pathogenicity.
• This slime mould represents a potential biological tool for LPS detoxification.