Effects of the anaerobic wood decay bacterium Clostridium xylanolyticum on unbleached Pinus and Eucalyptus pulp

Clostridium xylanolyticum has been shown to produce extracellular enzymes capable of degrading wood. The present work was conducted to quantify growth on various lignocellulosic substrates and degradation of pulped wood fibre. In the latter tests Clostridium xylanolyticum was incubated at 35°C under anaerobic conditions in a medium containing 0.2% (w/v) peptone and 4% (w/v) unbleached Pinus and Eucalyptus pulp. Xylan (0.1% w/v) was included to stimulate growth and induce xylanase production. After 1 weeks incubation material from both the uninoculated controls and inoculated tests was removed, washed, dried and hydrolysed using (72% w/v) sulphuric acid at 30°C for 45 minutes followed by 3% (w/v) sulphuric acid at 121°C for two hours. The hydrolysates were analysed for xylose content using HPLC which showed enzymatic degradation of the xylan fraction of the pulp. Other pulp tests showed that paper made from degraded Eucalyptus pulp had improved brightness, suggesting a possible role for this bacterium in future biological pulp bleaching research.