Kinetic study of aβ-mannanase from theBacillus licheniformisHDYM-04 and its decolorization ability of twenty-two structurally different dyes.
BACKGROUND
The microbialβ-mannanases have been increasingly exploited for bioconversion of biomass materials and various potential industrial applications, such as bleaching of softwood pulps, scouring and desizing, food and feed additive, and oil and textile industries. In this paper, aβ-mannanase was characterization from the bacteria,Bacillus licheniformisHDYM-04, which was a highβ-mannanase-producing strain (576.16 ± 2.12 U/mL at 48 h during fermentation).


METHODS
The michaelis constant (Km) and maximum velocity (Vmax) ofβ-mannanase were determined. The effect of organic solvents, inhibitors, detergents, chelating agents, oxidizing agents and reducing agents on the stability of enzyme were determined. The degradation of twenty-two structurally different dyes by the purifiedβ-mannanase produced by HDYM-04 was determined by full spectrum scan among 200-1000 nm at 0 min and 10 min, respectively.


RESULTS
β-Mannanase produced by HDYM-04 was highly specific towards glucomannan, where as exhibited low activity towards guar gum. Michaelis constant (Km) and maximum velocity (Vmax) of glucomannan substrate were 2.69 mg/ml and 251.41 U/mg, respectively. The activity of different organic solvents showed significantly difference (p< 0.05). It retained > 80 % activity in dimethyl sulfoxide, acetone, chloroform, benzene, hexane. In the presence of solvents, citric acid, ethylene diamine teraacetic acid and potassium iodide, it retained > 80 % residual activity. Twenty-two structurally different dyes could be effectively decolourised byβ-mannanase within 12 h, in which methyl orange (99.89 ± 2.87 %), aniline blue (90.23 ± 2.87 %) and alizalin (83.63 ± 2.89 %) had high decolorization rate.


CONCLUSIONS
The obtained results displayed that theβ-mannanase produced by HDYM-04 showed high stability under different chemical reagents and was found to be capable of decolorizing synthetic dyes with different structures. So, the reported biochemical properties of the purifiedβ-mannanase and its rapid decolorizations of dyes suggested that it might be suitable for industrial wastewater bioremediation.
Key Laboratory of Microbiology, College of Life Science, Heilongjiang University, Harbin, 150080 People's Republic of China.
Jingping
J
Ge
Key Laboratory of Microbiology, College of Life Science, Heilongjiang University, Harbin, 150080 People's Republic of China.|School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People's Republic of China.
Renpeng
R
Du
Key Laboratory of Microbiology, College of Life Science, Heilongjiang University, Harbin, 150080 People's Republic of China.
Dan
D
Zhao
Key Laboratory of Microbiology, College of Life Science, Heilongjiang University, Harbin, 150080 People's Republic of China.
Gang
G
Song
Key Laboratory of Microbiology, College of Life Science, Heilongjiang University, Harbin, 150080 People's Republic of China.
Man
M
Jin
Key Laboratory of Microbiology, College of Life Science, Heilongjiang University, Harbin, 150080 People's Republic of China.
Wenxiang
W
Ping
Bacillus licheniformis; Characterization; Dye decolorization; β-Mannanase