A mannanolytic thermophilic bacterium (L-07) was isolated from palm oil shell after 2 days of
enrichment in liquid medium supplemented with 1% palm kernel meal as mannan source. Sequence
analysis of 16S-rRNA indicated that L-07 was similar (98%) to  Geobacillus stearothermophilus, a
species of thermophilic aerobic bacteria. We found that  G. stearothermophilus L-07 produced
extracellular β-1,4-mannanases, but no β-manosidase and α-galactosidase activities. The growth of L-07
reached its maximum (3.0 x 106
 cell/ml) at 12-20 hours, while the highest  β-mannanase activity (0.52
U/ml) was observed in culture medium after 36 hours of cultivation at 60o
C. The medium containing
locust bean gum was the best for producing extracellular β-1,4-mannanases compared with kolang kaling,
konjak, and palm kernel meal. SDS-PAGE and zymogram analysis demonstrated that crude mannanase
complex of L-07 from locust bean gum containing medium comprised three active bands with molecular
weight of 85, 73 and 50 kDa.