Abstract
Rhamnolipids (RLs), the glycolipidic biosurfactants found initially as exoproducts of the opportunistic pathogen Pseudomonas aeruginosa, are characterized as virulence factors contributing to its pathogenesis infections. However, RLs are also produced by various bacterial species. They consist of a gluconic part, usually containing one or two rhamnoses, and a lipid part, containing one or two hydroxy-fatty acids. In this study, we present both the isolation of RLs from bacterial cultures of the non-pathogenic bacterium Thermus thermophilus as well as the development of the rabbit antibody directed against them. The antibody was titrated and evaluated, in respect of its recognition selectivity. Between both RLs constituents, it specifically recognized only the hydroxydecanoic acid between the fatty acids tested, contrary to rhamnose. The potential of the antibody to recognize both purified RLs and RLs present in crude extracellular media produced by T. thermophilus and Escherichia coli cultures, is evidenced by Dot Blot immuno-reaction. The development of this antibody is addressed in detail, as the sensitive analytical technique, and its potential use would facilitate the implementation of rhamnolipids’ detection, or may be a useful and promising tool for determining these microbial secondary metabolites and virulence factors secreted in extracellular culture media or in biological fluids during infections.
Highlights
Rhamnolipids (RLs) are glycolipids that are produced by some bacterial species but mainly and widely spread by Pseudomonas aeruginosa [1,2]
A correlation was reported between increased levels of RLs in the bronchial epithelium of patients with cystic fibrosis with established infection of the bacterium P. aeruginosa and the worsening of the clinical condition of the patients [7]
RLs secreted from the saprophytic bacterium Burkholderia pseudomallei, induced cytopathic changes, which were due to a progressive reorganization of the F-actin network resulting in impaired cell cycle progression and reduced phagocytic function of macrophages [16]
Summary
Rhamnolipids (RLs) are glycolipids that are produced by some bacterial species but mainly and widely spread by Pseudomonas aeruginosa [1,2]. RLs secreted from the saprophytic bacterium Burkholderia pseudomallei (causative agent of melioidosis, an infectious disease of humans and animals), induced cytopathic changes, which were due to a progressive reorganization of the F-actin network resulting in impaired cell cycle progression and reduced phagocytic function of macrophages [16]. This bacterium produces RhaRha-C14-C14 exhibiting a hemolytic activity and found that the albumin inhibits hemolytic activity of the RL [17]. The antibody was validated using as samples extracellular media from T. thermophilus and E. coli cultures containing RLs, as already previously confirmed by the quantitative colorimetric orcinol method
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