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| Microbial degradation of diazepam in simulated aquaculture water |
| Received:November 09, 2024 |
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| KeyWord:aquaculture;diazepam;microbial consortium;degradation characteristics;response surface optimization;degradation kinetics |
| Author Name | Affiliation | E-mail | | LIU Chongwan | Fresh Water Fisheries Research Institute of Jiangsu Province, Nanjing 210017, China
Fishery Analysis & Testing Center of Jiangsu Province, Nanjing 210017, China | | | ZHU Xiaohua | Fresh Water Fisheries Research Institute of Jiangsu Province, Nanjing 210017, China
Fishery Analysis & Testing Center of Jiangsu Province, Nanjing 210017, China | xhz824@sina.com | | YANG Hongsheng | Fresh Water Fisheries Research Institute of Jiangsu Province, Nanjing 210017, China
Fishery Analysis & Testing Center of Jiangsu Province, Nanjing 210017, China | | | WANG Minghua | Fresh Water Fisheries Research Institute of Jiangsu Province, Nanjing 210017, China | | | XU Zhihua | Fresh Water Fisheries Research Institute of Jiangsu Province, Nanjing 210017, China
Fishery Analysis & Testing Center of Jiangsu Province, Nanjing 210017, China | | | REN Di | Fresh Water Fisheries Research Institute of Jiangsu Province, Nanjing 210017, China
Fishery Analysis & Testing Center of Jiangsu Province, Nanjing 210017, China | | | MENG Yong | Fresh Water Fisheries Research Institute of Jiangsu Province, Nanjing 210017, China | |
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| Abstract: |
| Diazepam（DZP）residues in water pose a threat to human health and environmental ecology. To improve DZP biodegradation efficiency, we studied the optimal application conditions and degradation kinetics of DZP residues in aquaculture water by DZP-degrading microbial consortium, including Bacillus subtilis, yeast, Cladosporium cladosporioides, Aspergillus oryzae, Aspergillus niger, which were selected in previous study. The degradation characteristics of DZP by microbial consortium were optimized by performing the single factor test, Plackett-Burman test, steepest ascent hill climb test, and Box-Behnken test, and the results were verified under pilot-scale conditions. At the same time, the effects of microbial consortium on the physical and chemical properties of water and sediment, as well as the stress and survival rate of aquatic animals（such as bream and crucian carp）were analyzed. The results of single factor test showed that the degradation effect of DZP was obvious by environmental temperature, dissolved oxygen, pH and the amount of composite bacterial suspension. Plackett-Burman experiment was used to determine the main factors affecting the degradation of DZP, including dissolved oxygen, environmental temperature and the amount of composite bacterial suspension. On this basis, the steepest ascent test and Box-Behnken design were used to determine the fitting values of the three main factors：dissolved oxygen 8.5 mg·L-1, ambient temperature 25 ℃, and the amount of composite bacterial suspension 1.0%. Under the condition of the fitting value, the maximum predicted absolute degradation rate was 91.2%; the above results were verified under pilot conditions, and the absolute degradation rate was 90.5%, which was close to the maximum value predicted by the model and increased by 15.59% compared with that before optimization. The application of microbial consortium only had a significant effect on the pH of water and sediment, there was no significant effects on other environmrnt parameters, as well as stress indicators and survival rates of Carassius auratus and Parabramis pekinensis. The kinetic analysis showed that the maximum specific degradation rate was 59.62 ng·L-1·h-1 when the concentration of DZP was 150 ng·L-1.The microbial consortium in this study have high DZP degradation ability and do not have negative effects on aquaculture environment and aquatic animals. It can be effectively applied to the treatment of DZP residues in aquaculture water, and provides an economical and environmentally friendly feasible solution for the improvement of aquatic product quality and safety and the restoration of water ecological environment. |
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