AbstractResults of this study indicate that pioneer bacteria found in sapwood and discolored wood may: (1) contribute to wood discoloration, (2) alter the rate of cellulase activity of decay fungi, (3) interact with wood parenchyma to alter the rate of wood colonization by decay fungi, and (4) help provide growth factors and soluble nitrogen. Parenchyma cells appeared to be the major obstacle to the establishment of decay fungi in sapwood. Brief exposure to steam caused many changes in sapwood resulting in loss of vitality, and with it, loss of resistance to colonization by decay fungi. Whatever factors arc lost, bacteria alone do not restore them.