Highly efficient decolorization of Malachite Green by a novel Micrococcus sp. strain BD15.
OBJECTIVE
Malachite Green (MG) is used for a variety of applications but is also known to be carcinogenic and mutagenic. In this study, a novel Micrococcus sp. (strain BD15) was observed to efficiently decolorize MG. The purposes of this study were to explore the optimal conditions for decolorization and to evaluate the potential use of this strain for MG decolorization.


METHODS
Optical microscope and UV-visible analyses were carried out to determine whether the decolorization was due to biosorption or biodegradation. A Plackett-Burman design was employed to investigate the effect of various parameters on decolorization, and response surface methodology was then used to explore the optimal decolorization conditions. Kinetics analysis and antimicrobial activity tests were also performed.


RESULTS
The results indicated that the decolorization by the strain was mainly due to biodegradation. Concentrations of MG, urea, and yeast extract and inoculum size had significantly positive effects on MG decolorization, while concentrations of CuCl(2) and MgCl(2), and temperature had significantly negative effects. The interaction between different parameters could significantly affect decolorization, and the optimal conditions for decolorization were 1.0 g/L urea, 0.9 g/L yeast extract, 100 mg/L MG, 0.1 g/L inoculums (dry weight), and incubation at 25.2°C. Under the optimal conditions, 96.9% of MG was removed by the strain within 1 h, which represents highly efficient microbial decolorization. Moreover, the kinetic data for decolorization fit a second-order model well, and the strain showed a good MG detoxification capability.


CONCLUSIONS
Based on the results of this study, we propose Micrococcus sp. strain BD15 as an excellent candidate strain for MG removal from wastewater.
College of Life Science, Zhejiang University, 310058, Hangzhou, Zhejiang, People's Republic of China.
Lin-Na
LN
Du
Ming
M
Zhao
Gang
G
Li
Xiao-Ping
XP
Zhao
Yu-Hua
YH
Zhao
D001412:Bacillus subtilis / Q000378:metabolism; D001673:Biodegradation, Environmental; D048168:Escherichia coli K12 / Q000378:metabolism; D016015:Logistic Models; D008837:Micrococcus / Q000378:metabolism*; D008956:Models, Chemical; D012394:Rosaniline Dyes / Q000737:chemistry / Q000378:metabolism*; D013696:Temperature; D014508:Urea / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism*
D012394:Rosaniline Dyes; D014874:Water Pollutants, Chemical; C005095:malachite green; D014508:Urea