Mechanism Of Naphthalene Can Promote Chromate Reduction In Strain LZ-4

As the reach of Yellow River in Lanzhou city was severely contaminated by porycyclic aromatichydrocarbons (PAHs) and heavy metals, the integration of PAHs degradation and heavy metals reduction may become an important strategy for bioremediation of Lanzhou area. By collecting sediment samples from contaminated reach and screening in enrichments, Sirain LZ-4 which can degrade naphthalene and reduce chromate aerobically was isolated, and the ability of chromate reduction was determined under the condition of naphthalene or glucose as the sole carbon and energy source. When 200 μMor 500 μM chromate was added into medium culture, LZ-4 using naphthalene as sole energy source could reduce almost all chromate. When the medium culture contained 1mM chromate, LZ-4 depended on naphthalene as sole energy source can still reduce 42% of total chromate. However, whichever concentration of chromate we added into the medium culture, the strain using glucose as energy source could only reduce approximately 22% of total chromate. The draft genome sequencing, chemical reaction assays and enzyme activity assays were performed to further explain this interesting phenomenon. Furthermore, parts of enzymes involved in Naphthalene degradation, such as NahG and NahE, were purfied and crystalized, and the capacity of NahG that whether it can reduce chromate were test.Finallym, We assumed that the coactions of biological process and chemical reaction render LZ-4 using naphthalene as sole carbon and energy source can reduce more chromate, and predicted a mechanism on the degradation of Naphthalene and Chromate reduction pathway of strain LZ-4. This combined strategy suggested that the isolated LZ-4 may provide new insights into bioremediation and bioremediation in contaminated reach of Yellow River in the future.