Sugarcane bagasse as support for immobilization of Bacillus pumilus HZ-2 and its use in bioremediation of mesotrione-contaminated soils.
The degrading microorganisms isolated from environment usually fail to degrade pollutants when used for bioremediation of contaminated soils; thus, additional treatments are needed to enhance biodegradation. In the present study, the potential of sugarcane bagasse as bacteria-immobilizing support was investigated in mesotrione biodegradation. A novel isolate Bacillus pumilus HZ-2 was applied in bacterial immobilization, which was capable of degrading over 95 % of mesotrione at initial concentrations ranging from 25 to 200 mg L(-1) within 4 days in flask-shaking tests. Scanning electron microscope (SEM) images showed that the bacterial cells were strongly absorbed and fully dispersed on bagasse surface after immobilization. Specially, 86.5 and 82.9 % of mesotrione was eliminated by bacteria immobilized on bagasse of 100 and 60 mesh, respectively, which indicated that this immobilization was able to maintain a high degrading activity of the bacteria. Analysis of the degradation products determined 2-amino-4-methylsulfonylbenzoic acid (AMBA) and 4-methylsulfonyl-2-nitrobenzoic acid (MNBA) as the main metabolites in the biodegradation pathway of mesotrione. In the sterile soil, approximately 90 % of mesotrione was degraded after supplementing 5.0 % of molasses in bacteria-bagasse composite, which greatly enhanced microbial adaptability and growth in the soil environment. In the field tests, over 75 % of mesotrione in soil was degraded within 14 days. The immobilized preparation demonstrated that mesotrione could be degraded at a wide range of pH values (5.0-8.0) and temperatures (25-35 °C), especially at low concentrations of mesotrione (5 to 20 mg kg(-1)). These results showed that sugarcane bagasse might be a good candidate as bacteria-immobilizing support to enhance mesotrione degradation by Bacillus p. HZ-2 in contaminated soils.
Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, and Lab of Insect Toxicology, South China Agricultural University, Guangzhou, 510642, People's Republic of China.
Jie
J
Liu
Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, 510642, People's Republic of China.
Shaohua
S
Chen
Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, and Lab of Insect Toxicology, South China Agricultural University, Guangzhou, 510642, People's Republic of China.
Jie
J
Ding
Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, and Lab of Insect Toxicology, South China Agricultural University, Guangzhou, 510642, People's Republic of China.
Ying
Y
Xiao
Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, and Lab of Insect Toxicology, South China Agricultural University, Guangzhou, 510642, People's Republic of China.
Haitao
H
Han
Key Laboratory of Natural Pesticide and Chemical Biology, Ministry of Education, and Lab of Insect Toxicology, South China Agricultural University, Guangzhou, 510642, People's Republic of China. guohuazhong@scau.edu.cn.
Guohua
G
Zhong
D001407:Bacillus / Q000378:metabolism / Q000502:physiology*; D001422:Bacterial Adhesion; D001673:Biodegradation, Environmental; D002482:Cellulose / Q000378:metabolism*; D003512:Cyclohexanones / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D031786:Saccharum / Q000378:metabolism*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*; D013696:Temperature
D003512:Cyclohexanones; D012989:Soil Pollutants; C432907:mesotrione; D002482:Cellulose; C027433:bagasse
Bioremediation; Immobilization; Mesotrione; Metabolites; Sugarcane bagasse