Isolation, Identification And Degradation Characteristics Of The Nonylphenol Degradation Bacterial Strains

Nonylphenol(NP) is one of the representive endocrine disrupting chemicals and persistent toxic pollutants, with obvious estrogenic activity and high bioaccumulation in body. NP is an ultimate degradation product of nonylpenol polyethoxylates that is primarily used in cleaning and industrial processes. Its widespread use has led to the wide existence of NP in various environmental matrices, such as water, sediment, air and soil. The problem of NP pollution has became one of the word’s major environmental problens.Two strains used NP as sole carbon source were obtained through the screening, enrichment, separation and purification of strains in sediment samples, and named strain a and strain d4 respectively. Futher study has been done on the NP degradation characteristics, influencing factors and degradation kinetics model of strains a and d4.Results showed that:(1) According to their sequence analysis of 16 S r DNA as well as morphological physiological and biochemical characteristics, strain a was identified preliminarily as Ralstonia sp.; strain d4 was identified preliminarily as Pantoea sp..(2) When the temperature is 30 ℃ and NP concentration was 40 mg·L-1, the NP degradation caused by the strain a and d4 accorded with first-order kinetic model. Their NP biodegradation rate constants(k) were 0.190 and 0.223 day-1, respectively, and half-lives(t1/2) were 3.66 and 3.1 days, respectively.(3) The degrading conditions for strain a and d4 were optimized by tests in shaking flasks. The results showed that the optimal conditions for strain a degrading NP were: temperature 30 ℃, initial p H 6.0, initial NP concentration 20 mg·L-1 and inoculums amount 3%; the optimal conditions for strain d4 degrading NP were: temperature 30 ℃, initial p H 6.0, initial NP concentration 40 mg·L-1 and inoculums amount 3%.