Highly efficient decolorization of Malachite Green by a novel Micrococcus sp. strain BD15

• Published in: Environmental science and pollution research international 2011-08, Vol.19 (7), p.2898-2907
• Main Authors: Du, Lin-Na, Zhao, Ming, Li, Gang, Zhao, Xiao-Ping, Zhao, Yu-Hua
• Format: Article
• Language: English
• Subjects: Antimicrobial activity; Aquaculture; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Bacillus subtilis - metabolism; Biodegradation; Biodegradation, Environmental; Biosorption; Copper chloride; Decolorization; Detoxification; Dyes; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Escherichia coli K12 - metabolism; Experiments; Inoculum; Logistic Models; Microbiology; Micrococcus; Micrococcus - metabolism; Models, Chemical; Pallets; Research Article; Rosaniline Dyes - chemistry; Rosaniline Dyes - metabolism; Studies; Temperature; Toxicity; Urea; Urea - metabolism; Variables; Waste Water Technology; Water Management; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - metabolism; Water pollution; Water Pollution Control; Yeast; Yeasts
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-012-0796-1

Purpose 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. Conclusion Based on the results of this study, we propose Micrococcus sp. strain BD15 as an excellent candidate strain for MG removal from wastewater.