Adhesion of Pasteuria penetrans to the cuticle of root-knot nematodes (Meloidogyne spp.) inhibited by fibronectin : A study of electrostatic and hydrophobic interactions

Pasteuria penetrans is a bacterium with the potential to control plant-parasitic nematode populations; the mechanism of spore adhesion, however, is poorly understood. Attachment assays were performed in media supplemented with various concentrations of fibronectin and in the presence and absence of KSCN which modulates hydrophobic interactions. A reduction in the strength of the hydrophobic effect prevented spores from binding to the cuticle as did 20 mu g/ml fibronectin. It was also shown directly utilizing a newly-developed technique which utilizes 3-hexadecanoyl-7-hydrocoumarin as an indicator of the fibronectin binding to the spore surface that the presence of KSCN prohibited binding. This effect was interpreted to indicate that the reduction of binding was the direct result of the influence of hydrophobic interactions between the fibronectin and the spore surface. Western blot analysis of cuticle extracts of 12 Meloidogyne Incognita and Caenorhabditis elegans revealed small amounts of fibronectin to be present. Fibronectin, or a similar receptor, present in the cuticle could be responsible for the adhesion of P. penetrans by hydrophobic interactions.