Study On The Screening And Application Of Nicotine-degrading Bacteria

Nicotine,also known as nicotine,accounts for a large proportion of tobacco alkaloids.The area and output of tobacco planting in China are in the forefront of the world,and a large amount of wastewater will be produced in the process of tobacco processing.Nicotine in wastewater,because of its non-degradable characteristics,seriously endangers people's living environment.Many scholars at home and abroad have found a number of nicotine-degrading microorganisms through long-term experimental studies.The use of microorganisms and their products to degrade nicotine has high application value.The beneficial effects of nicotine-degrading content make more researchers involved.In this study,the contaminated soil of tobacco factory was used as experimental material.21 strains of nicotine-degrading strain were obtained after primary screening and rescreening.The best strains were screened to identify and determine the best growth conditions,and explored in tobacco processing.Applied research on wastewater treatment.The main conclusions are as follows:(1)The strain was screened on the enrichment medium with nicotine as the sole carbon and nitrogen source.The degradation ability of the strain was determined by ultraviolet spectrophotometry.The strain was screened again,and the highly efficient degradation strain was obtained.The number was E3.(2)MorpHological,pHysiological and biochemical tests were carried out on strain E3,and DNA fragments were extracted by molecular experiments.The strain sequences were obtained by gel electropHoresis,PCR amplification and molecular sequencing.Through Blast comparison,its status in bacterial classification was determined,and a pHylogenetic tree was constructed.The strain was identified as Ochrobactrum intermedium and named as O.intermedium E3.(3)By analyzing the culture conditions of strain O.intermedium E3 glucose content,peptone content,culture time and culture temperature,the suitable range of strain degradation conditions was obtained.The optimum culture condition of strain was determined by response surface method to be glucose content 15 g/L,peptone content 12 g/L,culture time 22 h,culture temperature 33?.Under this condition,the obtained nicotine degradation rate was 79.32%.The results of the validation test showed that the nicotine degradation rate of the strain was 79.28% under the optimizedconditions,which was similar to the predicted value.(4)To study the application of strain O.intermedium E3 in wastewater from tobacco processing,and to investigate the effect of strain O.intermedium E3 on tobacco processing wastewater from four aspects: temperature,pH,inoculum size and yeast extract concentration.The results of single factor test showed that the optimal conditions for the degradation ability of strain O.intermedium E3 were: optimum temperature was 35?,optimum pH was 7.0,optimum inoculum was 2 g/L,and optimum yeast extract concentration was 1.0 g/L.The optimum factors of temperature,pH and inoculum showed that the effect of nicotine degradation on strain O.intermediumE3 was not significant,and the average degradation efficiency was about 50%.However,when treated with the strain O.intermedium E3,the addition of1.0 g/L yeast extract can effectively degrade nicotine,and the degradation rate reaches100%.It can be seen that the addition of yeast extract concentration has a significant effect on the degradation ability of nicotine.The characteristics of the strains were studied,and the optimum growth conditions and formulations were obtained,which had a strong treatment effect on tobacco processing wastewater.