Study On Biodegradation Of Anthracene By High-Effectively Degrading Strain And Biosurfactant

The applicatioin and mechanism of anthracene biodegradation by degrading strain and biosurfactant were studied in this paper,including isolation,indentification and characteristics of anthracene-degrading strain,degradation mechanism of anthracene and its enzymatic degradation,biodegradation of PAHs in sediment,as well as the characteristics of biosurfactant and its application with degrading strain.An anthracene-degrading strain(A10) was isolated from contaminated soil and identified as Aspergillus fumigatus.The experimental results showed that the biodegradation rate could achieve approximately 83.00%in 7 days when initial concentration of anthracene was 10mg/L. The inoculum dosage,cell age and pH,temperature,anthracene concentration,salinity,dissolved oxygen,nutirition salts of medium had notable influence on anthracene degradation by strain A10.Lactose could most favorably accelerate degradation of anthracene as additional carbon source.Meanwhile,A.fumigatus A10 could utilize some aromatic hydrocarbons such as benzene, toluene,phenol etc.as sole source of carbon and energy,indicating its degrading diversity.Research on enzymatic degradation showed that the intracellular and extracellular enzymes secreted by strain A10 both had ability to degrade anthracene,while function of intracellular enzymes was more obvious in H₃PO₄ buffer.The activity of extracellular enzymes could be affected by some environmental factors such as pH and temperature.Heavy metal ions had suppressive effect on yield and activity of enzymes to some extent.The optimal carbon and nitrogen source for strain A10 were sucrose and(NH₄)₂SO₄,respectively,while the activity of enzymes reached the highest when C/N was 30.FT-IR,HPLC combined with GC-MS analysis exhibited that the structure of anthracene changed with the action of microbe,generating a series of metabolites,such as aromatic acid, aromatic ketone,aromatic aldehyde with one or two benzene rings,as well as saturated hydrocarbons.Anthracene was transferred to anthrone,anthraquinone and phthalic acid through ring-cleavage reactions.The biosurfactant secreted by Pseudomonas aeruginosa S6 possessed preferable surface characteristics.The critical micelle concentration of this biosurfactant was 50mg/L,while its surface tension was 29.3mN/m.The biosurfactant had favorable adaptability to changes of temperature,pH and salinity among certain ranges.This biosurfactant increased the solubility of phenanthrene in water by about 23 times compared with control.It could also effectively emulsify the crude petroleum and the stability of emulsion maintained over 80%.HPLC-ESI-MS analysis revealed this biosurfactant contained 13 rhamnolipid congeners, each composed of one or two rhamnoses residues together with one or two fatty acids of 8～12 carbons in length.Rha-Rha-C₁₀-C_12:1,Rha-C_12:1-C₁₀,Rha-C₁₀-C₁₀ and Rha-C₈-C₁₀ were four major components with percentage of 14.68%,13.43%,10.85%and 10.58%,respectively.Biosurfactant could affect biodegradation of anthracene.The biodegradation was enhanced by biosurfactant of 60mg/L while it was added 1 day before and at the same time with inoculum of strain A10.The degradation rate increased by 16.50%and 18.03%compared with control.In process of anthracene degradation,biosurfactant could be utilized by strain,suggesting its bioavailability,thus it was an environmentally friendly biological preparation.