Bacterial and Mold Resistance of Selected Tropical Wood Species

The biological resistance of 21 tropical wood species against bacteria and molds was studied. The gram-positive bacterium Staphylococcus aureus and the gram-negative bacterium Escherichia coli had none or negligible activity on surfaces of zebrano and magaranduba (up to 1 x10(6) CFU/mL), and they had negligible or medium activity on surfaces of macassar ebony, ovengol, santos rosewood, and iroko (from 1 x10(6) up to 1 x10(7) CFU/mL). These bacteria had high activity on surfaces of okoume, tineo, doussie, makore, and both reference woods, beech and Scots pine (usually over 1 x10(7) CFU/mL). The mold growth activity (MGA) of Aspergillus niger and Penicillium brevicompactum was minimal on surfaces of ipe, yellow balau, macassar ebony, doussie, bubinga, and merbau, but it was strong on surfaces of okoume, cerejeira, ovengol, wenge, sapelli, and both reference woods. When comparing individual biological tests of (a) bacterial and mold but also (b) bacterial, mold and rot with decaying fungi C. puteana and T. versicolor, no significant relationships were found. These results confirm that the bio-durability of woods is influenced not only by their molecular structure, but also by the attacking biological pest group.