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African Journal of Biotechnology

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Biodegradation of phenanthrene in artificial seawater by using free and immobilized strain of Sphingomonas sp. GY2B

X Tao, J Liu, G Lu, X Guo, H Jiang, G Sun

Abstract


Biodegradation has been suggested as an alternative way to remove polycyclic aromatic hydrocarbons (PAHs) from contaminated environment. Phenanthrene is a representative carcinogenic PAHs containing
“bay-region” and “K-region”. Strain Sphingomonas sp. GY2B is a high efficient phenanthrene-degrading strain isolated from crude oil contaminated soils and had a broad-spectrum degradation ability on PAHs
and related aromatic compounds. This paper reports the domestication of strain Sphingomonas sp. GY2B in artificial seawater (AS) and the immobilization of the strain onto rice straw. Results showed that adding 85% artificial seawater had very low impact on the growth and  phenanthrene degradation ability of strain GY2B being domesticated for five generations. Phenanthrene was rapidly degraded when the
growth of strain GY2B was in the exponential phase that the initial added 100 mgL-1 phenanthrene had been almost completely degraded within 66 h. The optimal immobilization carrier weight and length of rice straw were 25 gL-1 and 0.5 cm, respectively. The immobilized strain GY2B had high degradation rate both in mineral salts medium and 80% artificial seawater, and was higher than that of the free strain GY2B. More than 95% phenanthrene (100 mgL-1) was degraded within 32 h, and the phenanthrene degradation percentages were > 99.5% after 67 h for immobilized strains. Immobilization of strain GY2B with rice straw possesses a good application potential in the treatment of wastewater and bioremediation of estuary and offshore environment contaminated by phenanthrene.



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