Analysis of extracellular polymeric substances and bacterial community in mixed cultures for Cr(VI) reduction
ZHANG En-hua1,2, DAI You-fen2,3, XIAO Yong2, CHEN Bi-lian3, YANG Zhao-hui1, ZHAO Feng2
1. Key Laboratory of Environmental Biology and Pollution Control, College of Environmental Science and Engineering, Hunan University, Changsha 410082, China;
2. Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China;
3. College of Life Sciences, Fujian Normal University, Fuzhou 350108, China
To better understand the mechanisms of Cr (VI) reduction by mixed microbial communities, Cr (VI) bio-reduction was performed by mixed cultures from activated sludge under both aerobic and anaerobic conditions. The component and quantity of extracellular polymeric substances (EPS) were analyzed, and the bacterial communities were determined by high throughput sequencing. No chromium adsorption was observed by the mixed cultures in the present study. In the 12th acclimation cycle, 67% and 78% of Cr(VI) was reduced by the aerobic and anaerobic cultures in 72h, respectively. More EPS were extracted from control groups than that from Cr(VI)-treated groups. The diversities of bacterial communities in Cr(VI)-treated groups were lower than those in control groups. Proteobacteria, Firmicutes, Chloroflexi and Actinobacteria were the most dominant phyla in the inoculum sample. But, all samples were dominated by Proteobacteria after a culture of 36days with Cr(VI). While the relative abundance of Citrobacter in cultures was significantly decreased by Cr(VI), the relative abundance of Enterobacter was remarkably increased by Cr(VI).
Jeyasingh J, Philip L. Bioremediation of chromium contaminated soil:optimization of operating parameters under laboratory conditions[J]. Journal of Hazardous Materials, 2005,118(1):113- 120.
[5]
Cheung K, Gu J D. Mechanism of hexavalent chromium detoxification by microorganisms and bioremediation application potential:a review[J]. International Biodeterioration & Biodegradation, 2007,59(1):8-15.
Sun M, Li W W, Mu Z X, et al. Selection of effective methods for extracting extracellular polymeric substances (EPSs) from Bacillus megaterium TF10[J]. Separation and Purification Technology, 2012,95:216-221.
[9]
Yuan S J, Sun M, Sheng G P, et al. Identification of key constituents and structure of the extracellular polymeric substances excreted by Bacillus megaterium TF10for their flocculation capacity[J]. Environmental Science & Technology, 2010,45(3):1152-1157.
[10]
Frølund B, Palmgren R, Keiding K, et al. Extraction of extracellular polymers from activated sludge using a cation exchange resin[J]. Water Research, 1996,30(8):1749-1758.
[11]
Sheng G P, Yu H Q, Yue Z B. Production of extracellular polymeric substances from Rhodopseudomonas acidophila in the presence of toxic substances[J]. Applied Microbiology and Biotechnology, 2005,69(2):216-222.
[12]
Ledin M. Accumulation of metals by microorganisms-processes and importance for soil systems[J]. Earth-Science Reviews, 2000,51(1):1-31.
[13]
Sheng G P, Yu H Q, Li X Y. Extracellular polymeric substances (EPS) of microbial aggregates in biological wastewater treatment systems:a review[J]. Biotechnology Advances, 2010,28(6):882- 894.
[14]
Das S K, Guha A K. Biosorption of chromium by Termitomyces clypeatus[J]. Colloids and Surfaces B:Biointerfaces, 2007, 60(1):46-54.
[15]
Kang S Y, Lee J U, Kim K W. Biosorption of Cr (Ⅲ) and Cr (VI) onto the cell surface of Pseudomonas aeruginosa[J]. Biochemical Engineering Journal, 2007,36(1):54-58.
[16]
Doshi H, Ray A, Kothari I. Biosorption of cadmium by live and dead Spirulina:IR spectroscopic, kinetics, and SEM studies[J]. Current Microbiology, 2007,54(3):213-218.
[17]
Parikh S J, Chorover J. FTIR spectroscopic study of biogenic Mn-oxide formation by Pseudomonas putida GB-1[J]. Geomicrobiology Journal, 2005,22(5):207-218.
[18]
Ramesh A, Lee D J, Hong S. Soluble microbial products (SMP) and soluble extracellular polymeric substances (EPS) from wastewater sludge[J]. Applied Microbiology and Biotechnology, 2006,73(1):219-225.
Wu F, Tanoue E. Isolation and partial characterization of dissolved copper-complexing ligands in streamwaters[J]. Environmental Science & Technology, 2001,35(18):3646-3652.
[21]
Adav S S, Lee D J. Extraction of extracellular polymeric substances from aerobic granule with compact interior structure[J]. Journal of Hazardous Materials, 2008,154(1):1120-1126.
[22]
Komori K, Wang P C, Toda K, et al. Factors affecting chromate reduction in Enterobacter cloacae strain HO1[J]. Applied Microbiology and Biotechnology, 1989,31(5/6):567-570.
[23]
Schackmann A, Müller R. Reduction of nitroaromatic compounds by different Pseudomonas species under aerobic conditions[J]. Applied Microbiology and Biotechnology, 1991,34(6):809-813.
