P4: Production and properties of thermostable mannanase from thermophilic actinomycetes

Mannans are the major constituents of the hemicellulose fraction in softwoods and show widespread distribution in plant tissues. To produce thermostable mannanase for development of the enzymatic bioprocessing, we isolated a potent extracellular mannanase-producing thermophilic actinomycete, Thermobifida fusca BCRC19214 from compost soils. Konjac glucomannan, locus bean galactomannan and xylan were used as carbon sources for production of mannanase from T. fusca BCRC19214. The highest extracellular mannanase activity was found when T. fusca BCRC19214 was grown in a medium containing konjac glucomannan. When using konjac glucomannan as the carbon source, the mannanase activity accumulated in the broth in a 500 ml Hinton flask after 48 h of cultivation at 50^oC was measured as 275.8 U/ml. The optimum pH and temperature for mannanase were 8.0 and 70^oC, respectively. The purified mannanase exhibited a high level of activity with konjac glucomannan. After 30-min treatment, the DPw of konjac glucomannan obviously decreased from 4,673,423 to 4,582.