Screening Of A Highly Efficient Quinoline Degrading Strain And The Effects Of Domesticated Conditions On The Rate Of Quinoline Degradation

With the rapid development of chemical industry in recent years,the number of nitrogen heterocyclic compounds in water increase sharply.Quinoline and its derivatives is a typical pahs nitrogen heterocyclic compounds,which is often appeared in the printing and dyeing with pharmaceutical wastewater,coking wastewater and wastewater in steel.Because of heavy toxicity and teratogenic,carcinogenic,nad can also pollut the groundwater through soil,quinoline cause great potential harm.Scholars at home and abroad has selected a series of quinoline degradation bacteria,such as Rhodococcus sp.,Comamonas sp.,Burkholderia sp.,Pseudomonas sp.,etc.,but the research about the Bacillus sp.of the microbial degradation of quinoline is less reported.In the degradation of quinoline organic matter,the degradation efficiency is low whatever the bacteria,which has the serious influence in production practice.From activated sludge of wastewater treatment plant,the quinoline degradation bacterium H1 was sourced and isolated,which can tolerate 700 mg/L quinoline.But its initial degradation efficiency was low.To improve the quinoline degradation rate,we studied the quinoline degradation bacteria domesticated conditions and the biodegradation capability,and the following results were obtained:(1)A single strain H1 which was isolated from activated sludge had a strong ability of degrading quinoline,the dominant bacteria was separated,purified and domesticated by the culture medium with different quinoline concentrations as a sole carbon source,and 16 S rRNA gene sequences showed that the strain belonged to Bacillus sp..The degradation growth process was divided into inhibition period,adjustment period,logarithmic phase and decline phase.(2)When quinoline degradation bacterium Bacillus sp.H1 in 100 mg/L~700 mg/L quinoline concentration,the quinoline degradation was efficiency and we found that concentrations of quinoline tolerance was up to 700 mg/L.The optimal cultivating conditions were inoculation 20%,pH 7,temperature 37°C.(3)The research on the performance of degrading quinoline showed that both of the first quinoline conditions and time had effect on the quinoline degradation rate.(4)Glucose,phenol and pyridine had inhibition effect on the degradation of quinoline,acetic acid,ammonium chloride,urea,methanol had a role in promoting growth of bacteria,but they could not promote the degradation of quinoline.(5)At various concentrations,the degradation process accorded with zero order kinetics equation,when the initial concentration was smal,the degradation rate increased with quinoline concentration,and when the concentration was more than 440 mg/L,with the increase of the concentration of quinoline degradation rate showed a trend of decrease(6)With the degradation of quinoline,ammonia nitrogen concentration in the previous steady increased,at some point rose rapidly,reached the maximum after gradually reduce,while the concentration of nitrate nitrogen steady rose.The content of TOC decreased with the degradation of quinoline,and slower than the degradation of quinoline 50 hours.(7)Dehydrogenase activity showed a trend of increase with the degradation of quinoline,prophase maintained steady and rapid growth,reached the maximum in a very short time.But the timing of the dehydrogenase activity began to rapid growth is slower than the rapid degradation of quinoline for a period of time.Relative to the supernatant,the time of bacteria suspension degradation of quinoline was shorter,and the role of intracel ular enzyme was greater than the effect of extracel ular enzymes.But the degradation time of acteria suspension and intracel ular enzyme,supernatant fluid and extracel ular enzyme had certain gap.