Abstract:

【Objective】 Biodegradation is an effective and economic method to treat the soil environment that has been polluted by ethoprophos.The study focused on the isolating and characterizing bacteria with abilities to degrade ethoprophos.【Method】 The enrichment method was used to find the bacteria which can degrade the ethoprophos from the soil samples of long-term application of ethoprophos. The content of ethoprophos was determined by using UV. 【Result】 A bacterial strain DS-1 capable of utilizing ethoprophos as sole carbon source was isolated. It was preliminarily identified as Bacillus cereus according to its physiological-biochemical characteristics and the similarity analysis of its 16S rDNA sequence (GenBank Accession No. GQ149481). The growth and degrading characteristics of this strain were tested. The highest degradation rate of ethoprophos was up to 77.1% when ethoprophos concentration was 10 mg∙L-1, and the relative degradation amount of 50 mg∙L-1 was 26.8 mg∙L-1 which is the highest. The degradation rate of ethoprophos was 51.6% at 30℃, significantly higher than that at 4℃, 25℃ and 40 ℃. 【Conclusion】 The optimal temperature and pH for the ethoprophos degradation under the action of DS-1 were 30℃ and 7.0, respectively. The optimal carbon and nitrogen sources were sucrose, ammonium sulfate, and the optimum molar ratio of carbon to nitrogen was 4:1.

Key words: ethoprophos')">ethoprophos, biodegradation, isolation, identification, degradation characteristic