The Co-culture Of Advenella Sp.B9 And Stenotrophomonas Sp.N5 For The Synergistic Degradation Of Phenol And Fluoranthene

Phenol and polycyclic aromatic hydrocarbons(PAHs),as the common industrial pollutants,are often found as co-contaminants in the environment including the coking wastewater.Phenol has a relatively higher water solubility and is widely known to be acutely toxic to organisms.In addition to toxicty and carcinogenicity,PAHs can also accumulate in biological organisms and then threaten human health through the delivery of food chains.At present,the total PAHs concentration in the effluent of coking wastewater treatment plants is at a low level,which is able to meet emission standard.However,PAHs were not effectively biodegraded by microorganisms but concentrated on sludge during biological treatment.After the sludge containing high concentration of PAHs was treated by composting,landfilling,incineration,etc.,which caused secondary pollution to the soil,water,atmosphere and other environments,further affected the biological organisms including humans.Therefore,it is particularly important to improve the PAHs degradation efficiency of microorganisms during the biodegradation treatment.Co-metabolism enhanced biodegradation technology is a common method to improve the removal of refractory organic pollutants.Phenol as a more available organic matter than PAH,is the best choice for co-matabolism to enhance the PAHs biodegradation technology by providing energy for the growth and reproduction of microorganisms.In order to improve the degradation efficiency of PAHs in treatment process,the co-culture system was constructed by mixing the isolated strain Advenella sp.B9 with the laboratory-preserved strain Stenotrophomonas sp.N5 to explore the effect of phenol on the degradation of fluoranthene.In addition,four-ring fluoranthene was used as a representative of PAHs to study the biodegradation of PAHs by phenol as co-substrate in co-culture system.The main results are as follows:(1)Two strains were inoculated separately in the inorganic salt medium with 500 mg/L phenol by separate culture and co-culture.After 24 h,the degradation of phenol by Stenotrophomonas sp.N5 was negligible,and the degradation of phenol by Advenella sp.B9 was 69.8%.A necessary synergistic interaction among Stenotrophomonas sp.N5 and Advenella sp.B9 took place in the phenol degradation.(2)By micro-transcript sequencing of microbial cells,when Advenella sp.B9 and Stenotrophomonas sp.N5 were cultured alone,the gene expression of Advenella sp.B9 monooxygenase was more than 6 times than that of Stenotrophomonas sp.N5 phenol hydroxylase enzyme.The enzyme involved in hydroxylation of phenol os only the monooxygenase transcribed by Advenella sp.B9,while the dioxygenase transcribed by Stenotrophomonas sp.N5 did not decrease but increase in co-culture.In conclusion,the two strains promote the biodegradation of phenol by competing for hydroxylated phenol.(3)In the co-culture system,the addition of phenol increased the degradation efficiency of 10 mg/L fluoranthene from 0.389 mg/L/d to 0.509 mg/L/d compared with the phenol-free group.When the initial concentration of phenol was 800 mg/L,the most effective promotion of fluoranthene biodegradation was that the degradation efficiency of fluoranthene was increased by 88.5%.