Screening And Biological Characteristics Of Low Temperature Naphthalene And Phenanthrene Degrading Bacteria

Polycyclic aromatic hydrocarbons(PAHs)are a wide range of organic pollutants with potential carcinogenic,teratogenic and amphogenic effects.Due to its stable chemical structure and strong hydrophobicity,PAHs have anti-degradation and accumulation properties,and are long-term and stable in various environmental media.The winter temperature in northern China is low,and the activity of degrading bacteria with an optimum growth temperature above 20°C is inhibited.It is necessary to screen strains that are resistant under low temperature conditions and have strong degradation ability to PAHs.This study applied traditional microbial culture techniques to analyze the community structure of bacteria in contaminated soil near Daqing Oilfield.As a result,25 strains of 164 strains of bacteria were isolated,and the number of bacteria was between(0.54~1.04)×10~6 CFU/mL.Morphological observation,physiological and biochemical characteristics were identified for the strains,and 12 genera were identified.There were two distinct dominant genus,which were the genus Sporosarcina sp.and Pseudomonas sp.and the rest were common genus.For the culturable microorganisms in the contaminated soil,5 strains of naphthalene and 4 strains with phenanthrene as the sole carbon source were isolated under low temperature conditions by enrichment culture method and pollutant concentration gradient acclimation method.Comprehensive morphological observation,according to the eighth edition of the Berger Bacterial Identification Manual,the results of physiological and biochemical identification and molecular biological identification showed that No.1 belongs to Brevibacterium,No.5 belongs to Alcaligenes and B was a bacterium belonging to the genus Acinetobacter.The remaining bacteria belong to the genus Pseudomonas.The degradation ability of all strains was determined for 10 days.The degradation rates of naphthalene on the 10th day of low temperature naphthalene degrading bacteria 1,2,3,4 and 5 were between 75%and 99%,respectively.The degradation efficiency is high,named as GN1 and GN2.The degradation rate of phenanthrene on the 10th day of low temperature phenanthrene degrading bacteria A,B,C and D was 50%to 70%,respectively,and the degradation efficiency of A and B bacteria was higher,named as GP1 and GP2.Through the degradation ability test,strains with high-efficiency degradation ability were selected for growth characteristics determination.The optimal growth conditions for the two low-temperature naphthalene degrading bacteria were as follows:naphthalene concentration 300 mg/L,pH 7.0,culture temperature 10°C,and culture rotation number 120 r/min.The optimal growth conditions for the two low-temperature phenanthrene-degrading bacteria were:pH 7.0,culture temperature 10°C,and culture rotation number 120 r/min.At the same time,the concentration of phenanthrene in the phenanthrene-inorganic salt medium has similar effects on the growth of GP1 and GP2degrading bacteria,and all five levels can be used.