Antibacterial properties of Scots pine and Norway spruce

Wooden surfaces in interior use hold potential for improving human health and wellbeing. The antibacterial properties of wood might reduce the possibility of cross-contamination from surfaces. In order to be able to control the hygienic quality of the wooden surface, the antibacterial effect should be better understood. The main aim of this thesis was to identify and evaluate the antibacterial properties of wood and its components. Different methods were developed and used to study the antibacterial properties of Scots pine and Norway spruce, heartwood and sapwood. The solid wood surface showed clear antibacterial properties, even when the extractives had been removed with acetone. Studies with the extracts showed several human pathogens, including methicillin-resistant Staphylococcus aureus, to be susceptible to pine heartwood and sapwood in particular, and also, to some extent, spruce. Besides extractives, lignin was the only separate wood component showing antibacterial properties. Wood volatile organic compounds (VOCs), which were studied in gaseous form, showed an antibacterial effect against various human pathogens. Several antibacterial compounds were found in all the extracts, however, they did not always explain the order of antibacterial activity between wood species. No single compound could alone explain the effect, hence the antibacterial effect derives either from different mechanisms in different species or from a synergistic effect. α-pinene and limonene could partly explain the antibacterial effect of the VOCs, but other components were also found to have an influence. Wood was found to have various antibacterial parts and a diverse range of bacterial pathogens that were sensitive to it. These results offer a good ground for the exploitation of the hygienic properties of wood and a good starting point for enhancing them further. Additionally, the extracts showed promising qualities and they should be studied further in regard to resistant pathogens.