Aerobic Biodegradation of Chlorinated Hydrocarbons by Bacillus circulans WZ-12 CCTCC M 207006 under Saline Conditions

• Published in: Chinese journal of chemical engineering Vol. 21; no. 7; pp. 781 - 786
• Main Author: 於建明 蔡文吉 赵士良 王艳 陈建孟
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2013
• Subjects: Bacillus circulans; Bacillus circulans WZ-12; Biodegradation; Chemical engineering; chlorinated hydrocarbons; Chlorination; Degradation; Effluents; Hydrocarbons; NaCl浓度; Saline; salinity; 动力学分析; 氯代烃; 环状芽孢杆菌; 生物降解性; 生理盐水; 盐碱条件; 静息细胞; chlorinated hydrocarbons; salinity; biodegradation; Bacillus circulans WZ-12
• ISSN: 1004-9541; 2210-321X
• DOI: 10.1016/S1004-9541(13)60536-4

A novel saline-tolerant bacterium Bacillus circulans WZ-12 was evaluated for its potential to degrade four chlorinated hydrocarbons under saline conditions. CHECl2 was effectively degraded by Bacillus circulans WZ-12 cells in the medium containing NaCl concentrations ranging from 5 g.L^-1 to 10 g-L^-1, and the maximum degradation efficiency （85%） was achieved at NaCl concentration of 10 g.L^-1. Similarly, Bacillus circulans WZ-12 was able to degrade CH2BrCl, C2H4Cl2, and C2H2Cl2 in the presence of 10 g NaCl per liter within 24 h. Cells of Bacillus circulans WZ-12 grown in minimal salt medium contained low levels of glycine betaine （GB）, but GB levels were 3- to 5-fold higher in cells grown in media with high salt. Kinetic analysis revealed that biodegradation of the four chlorinated hydrocarbons was concentration dependent and a linear inverse correlation （R2= 0.85-0.94） was observed between the rate of biodegradation （V） and salt concentration from 5 g.L〈 to 60 g.L-1. The growing cells （in minimal salt medium） degraded approximately 50% of the CH2C12 within 24 h, whereas the resting cells （in physiological saline） degraded only 25% of the CH2C12 within 24 h and were inactive after 36 h cultivation. Biodegradation could be repeatedly performed for more than 192 h with more than 50% removal efficiency. Bacillus circulans WZ-12 grows well in an aqueous/oil system, hence, it is effective for the treatment of industriai efflu- ents that contain chlorinated hydrocarbons with high salt concentrations.