Isolation and degradation pathway of a naphthalene-degrading strain

A bacterial strain W1 which could use naphthalene as the sole carbon source was isolated from oil-polluted soil of Shengli oil field.It was preliminarily identified that W1 belonged to Serratia sp.by the morphology,physiological-biochemical characteristics and sequencing analysis of the 16S rDNA.The optimal temperature and pH for its growth were 35 ℃ and 7.5.It could tolerate the high concentration of NaCl and naphthalene.Under the treatments of 30 g/L NaCl,the degradation rate of naphthalene was 80.9% after culture for 3 days when the naphthalene concentration was 100 mg/L,even the degradation rate reached 15.8% when 800 mg/L.According to the analysis of GC-MS and the absorbance measured of different substrates,the W1 strain could utilize other aromatic hydrocarbons,such as phenol,methylbenzene,benzoic acid,1-Naphthalenol,acetone and octane for growth.It also could degrade aliphatic hydrocarbon of C20-C23,C33-C36 in crude oil.The pathway of naphthalene degradation was measured by scanning the metabolic intermediates of degradation with UV-Vis.The possible degradation pathway of W1 strain was catechol pathway.Naphthalene was first turned into salicylic acid,and then pyrocatechol,small molecule substance by opening benzene ring,finally entered the tricarboxylic acid cycle.