Immobilization of fungal spores by adhesion.

Immobilization of conidiospores of Phanerochaete chrysosporium by adhesion was investigated in static and flow conditions on flat and on porous supports. Reducing the electrostatic repulsion between the spores and the support by adsorption of polycations on the support allows a better adhesion efficiency and a higher density of adhering spores and does not affect germination and growth. Formation of spore aggregates either in the suspension (high ionic strength) or on the support tends to decrease the surface coverage and to give an inhomogeneous distribution of adhering spores due to detachment of aggregates. The density of spores adhering from a flowing suspension is lower as compared with static conditions and does not exceed about 2% of surface coverage; this is due to the influence of tangential forces, to the short contact time with the surface, and to perturbation of the hydrodynamics along the surface by the previously immobilized spores. Obtaining a high coverage of the support by immobilized spores requires the absence of a tangential motion. (c) 1995 John Wiley & Sons, Inc

Surface properties of the conidiospores of Phanerochaete chrysosporium and their relevance to pellet formation.

The conidiospores of the white rot basidiomycete Phanerochaete chrysosporium tend to aggregate during swelling and germination in agitated liquid medium; as time passes, the initial aggregates tend to associate together and to capture conidiospores that remain isolated. The surface chemical compositions of the conidiospores and of developed hyphae were analyzed by X-ray photoelectron spectroscopy. The data were interpreted by modelling the surface in terms of proteins, polysaccharides and hydrocarbonlike compounds. The surface molecular composition of the dormant conidiospores was estimated to be about 45% proteins, 20% carbohydrates, and 35% hydrocarbonlike compounds. There was an increase in the polysaccharide content during germination. Later, when the hyphae were developed, the polysaccharide content became still higher, and the protein content dropped. The initial step of aggregation is attributed to polysaccharide bridging; its occurrence cannot be explained by a change of the overall hydrophobicity or electrical properties of the conidiospores

Robust and versatile grafted bacteriostatic polymer surfaces based on ionenes

International audienceMicrobial contamination are of great concern for many environmental, industrial and medical applications. Contact-active coatings with immobilized antimicrobial agents provide an efficient approach to limit the residual toxicity while maintaining efficient antibacterial properties. Antimicrobial polymers are of particular interest, as they generally possess long-term activity with a strong chemical stability. Among them, poly-cations with a proportionate amphiphilic character efficiently disrupt the outer and the cytoplas-mic membrane which affords lysis of bacteria. In the present research work, we covalently grafted ionenes onto different surfaces using a robust and efficient method based on polydopa-mine coating and diazonium salt induced polymerisation 1. Ionenes are particularly good candidates since they possess quaternary ammo-niums separated by hydrophobic fragments (PI x,y). Moreover, lack of toxicity 2 and ability to mitigate resistance development 3 has been demonstrated. Detailed characterizations of the grafted surfaces have been performed (XPS, FTIR spectroscopy, surface energy measurements). We tested the adhesion and antibacterial properties of the grafted surfaces using Staphylococcus aureus (Gram+) and Escherichia coli (Gram-). Results obtained from microbiology tests demonstrated the bacteriostatic and pro-adhesive properties of the ionene grafted surfaces. We clearly showed that our treated surfaces with ionenes led to an important reduction of bacteria, depending on the length of the hydrophobic spacer in the ionene (Figure 1). Finally, these modular polymer coatings would be particularly attractive as inhibition traps, leading to tremendous potential application in medical and industrial field