Screening of psychrotrophic tetracycline degrading strain and its preliminary application of tetracycline degradation in pig manure under low temperature
Tetracycline is a commonly used antibiotic in animal husbandry.Its broad spectrum and difficult metabolism lead to its widespread presence in animal manure.A tetracycline degrading strain was isolated from the sewage sludge of a tetracycline veterinary drug factory in severe cold area by enrichment screening method.According to the microscopic morphological characteristics,physiological and biochemical characteristics and molecular biological identification of the strain,it was identified as Serratia sp.ZS-8,and its tetracycline degradation rate could reach 63.9%(Degradation efficiency 0.190 mg·L-1·h-1)in 7 days at 10℃.The main factors affecting the degradation of tetracycline were screened by Plackett-Burman(PB)Design,and then the main factors were optimized by Box Behnken Design.The optimal degradation conditions were obtained as follows:temperature 18.0℃,pH 7.0,substrate concentration 50 mg·L-1,inoculum size 4.4%,and the degradation rate was 65.2%,which was 2.03%higher than that before optimization.When the strain was inoculated into pig manure at 10℃,the tetracycline residue in pig manure decreased from 11.4 mg·kg-1 to 3.84 mg·kg-1 in 30 days,and the degradation rate was 64.5%,significantly higher compared with the control group(22.9%).
low temperaturepsychrotrophic tetracycline degrading strainoptimization of degradation conditionspig manure
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