AbstractIn this study it was aimed to improve impregnability of spruce (Picea orientalis L.) wood with bacteria (Bacillus licheniformis A1) pretreatment, using copper/chromium/arsenic Type C (CCA-C) andcopper azole Type A (CBA-A). The effects of Bacillus licheniformis A1 on weight loss, copper uptake, and compression strength of samples were determined. Weight loss was slightly changed by bacterial degradation in all test groups. The best copper uptake cases were 1466 ppm for CCA-C and 2730 ppm for CBA-A. Improvement on copper uptake with bacteria pretreatment was in a range of 18 to 103% compared to control samples. Compression strength was decreased by bacterial degradation. However strength losses might be acceptable for several construction applications. Bacillus licheniformis A1seems to havea good potential for increasing the permeability of spruce wood.