Fig 1.
Screening for cellulolytic activity of five bacterial strains on CMC agar plate and fermentation liquid medium.
Fig 2.
Phylogenetic tree of Geobacillus sp. HTA426 associated with other members of the genus Geobacillus sp. and Bacillus sp.; The tree was obtained using the 16S rRNA sequence retrieved from the database by using the neighbor-joining method.
The bootstrap values were generated from 1000 replicates.
Fig 3.
Effect of culture media and incubation periods on cellulase production by Geobacillus sp. HTA426.
(a) Isolated strain cultured in Mandel and Reese medium (MR), Minimum Salt medium (MS), and Bushnell Haas medium (BHM) supplemented with CMC as the sole carbon source. (b) Isolated strain cultured in Mandel and Reese medium at 60°C. CMCase activity was investigated at 24 h intervals for up to 168 h by using DNS reagent.
Table 1.
Summary of purification of the cellulase produced by Geobacillus sp. HTA426.
Fig 4.
SDS-PAGE and zymogram of the purified cellulase produced by Geobacillus sp. HTA426.
M: protein maskers, Lane 1: ammonium sulfate precipitate of culture supernatant, Lane 2: fraction with highest cellulase activity collected from ion exchange chromatography, Lane 3: zymogram of the cellulase activity of the purified enzyme. Based on the gels, the molecular weight of the enzyme was estimated to be 40 kDa.
Fig 5.
Effect of (a) pH on enzyme activity, (b) pH on enzyme stability; pH 3.0 (♦), pH 4.0 (□), pH 5.0 (▲), pH 6.0 (■), pH 7.0 (Δ), pH 8.0 (○), pH 9.0 (●), and pH 10.0 (×), (c) temperature on enzyme activity, and (d) temperature on enzyme stability; 30°C (♦), 40°C (□), 50°C (▲), 60°C (■), 70°C (Δ), 80°C (○), and 90°C (●).
Fig 6.
Effect of various additive on enzyme activity.
Table 2.
Chemical composition of untreated and pretreated lignocellulosic biomass.
Fig 7.
Effect of incubation periods and concentrations; (a) 1%, (b) 3% and (c) 5% of pretreated sugarcane bagasse, rice straw, and water hyacinth on cellulase production by Geobacillus sp. HTA426.