Study On The Synergistic Effects And Degradation Of Typical Oxygen-Containing Polycyclic Aromatic Hydrocarbons1-Naphthol By Two Symbiotic Bacteria

1-naphthol is a typical oxygen-containing polycyclic aromatic hydrocarbon?OPAHs?which is easily accumulated during the degradation of polycyclic aromatic hydrocarbons?PAHs?.It is difficult to be degraded,has high toxicity,is easy to diffuse and directly affects the repairing effect of PAHs polluted environment.Arthrobacter and Bacillus are widely present in the natural soil environment,and there is no pathogenic effect.Arthrobacter crystallopoietes NT16 and Bacillus NG16 were the two symbiotic strains isolated from the contaminated soil of OPAHs in the early research group.The characteristics and synergistic mechanism of degradation of 1-naphthol will lay the foundation for the synergistic degradation of microbial communities in the actual restoration of OPAHs.In this paper,HPLC,TOC,GC-MS were used as the main detection methods,1-naphthol was used as the target pollutant,and the nutrition and culture conditions of1-naphthol degradation by NT16 and NG16 were optimized.The two strains were used to investigate characteristics,synergistic degradation mechanisms and interaction characteristics to determine the following results:?1?NG16 can maintain high cell growth activity in the presence of 1-naphthol with the highest concentration of 50 mg/L;the optimum pH range for growth of NT16 and NG16 with 1-naphthol as the sole carbon source is 7.5⁸ and 6⁸,the optimum efficiency of degradation of 1-naphthol by the two strains was 55%and 58%respectively;The NaCl content affected the efficiency of degradation of 1-naphthol by NT16 and NG16,the highest NaCl content can reach 8 g/L;the concentration of Fe³⁺was significantly NT16 metabolic activity of 1-naphthol incubation,the optimum Fe³⁺concentration of 0.9².7 mg/L,the metabolic efficiency is significantly improved.?2?The sulfur source affected the efficiency of 1-naphthol metabolism by NT16and NG16.The stronger the reduction of sulfur-containing inorganic compounds,the less suitable as the sulfur source of the two strains.SO₄^2-was the most suitable sulfur source for the two strains.The suitable sulfur source content could improve the efficiency of the 1-naphthol metabolism of the strain.When the SO₄^2-concentration was0.5×10^-33 mol/L,compared with the no sulfur source system.The degradation efficiency of 1-naphthol by NT16 and NG16 increased by about 15%and 10%respectively in 5days.The coexisting carbon sources such as malonic acid,succinic acid and glutaric acid could accelerate the metabolism of 1-naphthol by NT16 and NG16.Among them,the promotion effect of malonic acid was the most obvious.Compared with the non-coexisting carbon source,the degradation efficiency of 1-naphthol by NT16 and NG16 was increased by about 15%and 20%respectively,and the salinity was also significantly improved.P-hydroxyphenylacetic acid was an intermediate product that was easily accumulated in the degradation of 1-naphthol by NG16.The accumulation of p-hydroxyphenylacetic acid inhibited the degradation and mineralization of 1-naphthol by NG16.However,when p-hydroxyphenylacetic acid and 1-naphthol coexisting,it could accelerate the degradation efficiency and salinity of NT16 bacteria to 1-naphthol.?3?NT16 and NG16 could synergistically promote the degradation and mineralization of 1-naphthol.Compared with single NT16 and single NG16,the OD_600nm00nm values of the two strains increased by 0.8⁰.4 with 1-naphthol as carbon source under the optimal compounding ratio of 1:1 respectively,degradation of 1-naphthol The rates were increased by 20%and 10%respectively.The synergistic degradation of1-naphthol by NT16 and NG16 could be carried out in two ways:First,1-naphthol was hydroxylated and then opened to enter the phthalic acid metabolic pathway.NT16 was more likely to enter this pathway,while NG16 was difficult to degrade 1-naphthol through this pathway;second,1-naphthol was hydroxylated and then opened to enter the phenylpropionic acid metabolic pathway.NG16 rapidly converted 1-naphthol to p-hydroxyphenylacetic acid and accumulated significantly,while NT16 could not efficiently degrade 1-naphthol,but it could rapidly degrade p-hydroxyphenylacetic acid produced by NG16 and transform it into small organic acid.The two strains synergistically degraded the metabolic pathway of 1-naphthol to achieve high-efficiency mineralization of 1-naphthol.