Characterization of Cellulolytic and Xylanolytic Enzymes of <italic>Bacillus licheniformis</italic> JK7 Isolated from the Rumen of a Native Korean Goat

Abstract

A facultative bacterium producing cellulolytic and hemicellulolytic enzymes was isolated from the rumen of a native Korean goat. The bacterium was identified as a Bacillus licheniformis on the basis of biochemical and morphological characteristics and 16S rDNA sequences, and has been designated Bacillus licheniformis JK7. Endoglucanase activities were higher than those of β-glucosidase and xylanase at all temperatures. Xylanase had the lowest activity among the three enzymes examined. The optimum temperature for the enzymes of Bacillus licheniformis JK7 was 70°C for endoglucanase (0.75 U/ml) and 50°C for β-glucosidase and xylanase (0.63 U/ml, 0.44 U/ml, respectively). All three enzymes were stable at a temperature range of 20 to 50°C. At 50°C, endoglucanse, β-glucosidase, and xylanase had 90.29, 94.80, and 88.69% residual activity, respectively. The optimal pH for the three enzymes was 5.0, at which their activity was 1.46, 1.10, and 1.08 U/ml, respectively. The activity of all three enzymes was stable in the pH range of 3.0 to 6.0. Endoglucanase activity was increased 113% by K+, while K+, Zn+, and tween 20 enhanced β-glucosidase activity. Xylanase showed considerable activity even in presence of selected chemical additives, with the exception of Mn2+ and Cu2+. The broad range of optimum temperatures (20 to 40°C) and the stability under acidic pH (4 to 6) suggest that the cellulolytic enzymes of Bacillus licheniformis JK7 may be good candidates for use in the biofuel industry.

Enhanced Cellulase Production by a Novel Thermophilic Bacillus licheniformis 2D55: Characterization and Application in Lignocellulosic Saccharification

“…(Sadhu et al 2013). In the case of B. licheniformis JK7 pH 5.0 has been reported for optimum activity (Seo et al 2013) as well as Bacillus and Geobacillus sp. (Rastogi et al 2010).…”

“…With further increase in incubation temperature, to 90 and 100 °C, CMCase activity retained about 74% and 64% residual activity respectively, at 1 h incubation. Previous report showed that thermostable cellulase from B. licheniformis JK7 (Seo et al 2013), retained only about 25% of its original activity when incubated at 80 °C for 1 h. Another Bacillus sp. isolated from deep surface of homestake gold mine exhibited a thermostable cellulase (Rastogi et al 2009); however, the enzyme completely lost its activity over 1 h incubation at 90 and 100 °C.…”

Isolation, Cellulase Activity Test and Molecular Identification of Selected Cellulolytic Bacteria Indigenous Rice Bran

“…The increased of enzyme production was associated with the increased of cell growth, which indicated that cellulose was actively used by cellulolytic bacteria during the growth phase [20].…”

“…The production of cellulase enzymes was conducted for 24 h [22]. The exponential phase of Bacillus licheniformis JK7 took place over 6-16 h [20]. Cell growth decline in the stationary phase, caused by the metabolites repression after hydrolysis into glucose and cellobiose.…”

The Effects of Wood Storage on the Chemical Composition and Indigenous Microflora of Eucalyptus species Used in the Pulping Industry

“…(Adair et al 2002;Rajala et al 2010;Kropacz and Fojutowski 2014;Zhang et al 2014;Szulc et al 2017). The microorganisms detected in the wood chips of different Eucalyptus species have the potential to produce cellulolytic, hemicellulolytic, and xylanolytic enzymes (Schmidt 2006;Seo et al 2013;Nandimath et al 2016), which would affect the chemical composition of the wood material. E. dunnii (SQ4) exhibited the lowest diversity of indigenous microorganisms, which supports the idea of minimal degradation of cellulose fibers as evidenced by the high pulp yield and viscosity levels obtained for this species, making it the most suitable species for pulping.…”