Characterization Of Mycobacterium Sp.WY10 And Its Biodegradation To Phenanthrene And Pyrene

Polycyclic aromatic hydrocarbons(PAHs)are ubiquitous organic pollutants with carcinogenicity,teratogenicity,and mutagenicity in the environment,which imperil the health of human and ecosystems.The remove of PAHs from the environment has been widely studied all over the world.Many studies indicated that microbial remediation is one of the main methods to remove PAHs from the environment efficiently.Therefore,obtainment of PAHs-degrading bacteria and thoughly understanding of its remediation effect in the bioremediation process provide important guiding significance for the removal of PAHs in the comtaminated environment.In this study,a phenanthrene and pyrene-degrading strain WY10 was isolated from the PAHs-polluted soil.The characteristics,optimal biodegradation conditions,bioremediation potential in phenanthrene or pyrene contaminated soils of strain WY10,and abundance of PAHs-degrading genes in bioremediation of the contaminated soil were further investigated.The main results are as follows:(1)The strain WY10 was identifies as genus Mycobacterim based on the analysis of morphological features,physiological-biochemical characteristics and sequence of 16S rRNA,hsp65,recA and rpoB.(2)The strain WY10 could degrade phenanthrene and pyrene at a condition of temperature at 20-35?,pH 4.5-8.5.The optimal conditions to degrade phenanthrene and pyrene by strain WY10 was pH 4.5-7.5,30-35? and pH 4.5-7.5,28-35?respectively.Up to 100.0%of phenanthrene(100 mg·L-1)and 92.3%of pyrene(50 mg·L-1)were degraded in 72 hours under the condition of temperature at 28?,pH 6.5.Except the first 24 hours,the addition of glucose and maltose could accelerate the degradation of pyrene by strain WY10.There is no significant influence of the addition of fructose,glucose,and maltose at 100 mg L-1 on the degradation of phenanthrene and pyrene(3)Phenanthrene and pyrene in soils were degraded effectively by strain WY10.In the strain WY10 added soils,phenanthrene and pyrene were decreased rapidly from 39.8 mg·L-1 to 3.0 mg·L-1,and 18.2 mg·L-1 to 1.1 mg·L-1,respectively,after 35-day of incubation.The indigenous microorganism in control soils could also degrade phenanthrene(39.8 mg-L-1)and pyrene(18.2 mg·L-1)to a concentration of 5.0 mg·L-1 and 2.9 mg·L-1 at the 35th day,respectively.(4)The abundance of Mycobacterium 16S rRNA,RHD?-GP,nidA,and nidB gene increased with the degradation of phenanthrene and pyrene in soils.The residual concentrations of phenanthrene and pyrene were negatively correlated with the abundance of Mycobacterium 16S rRNA,RHD?-GP,nidA and nidB genes during the phenanthrene and pyrene rapidly degrading period.It revealed that Mycobacterium and bacteria with RHDa-GP,nidA and nidB genes might play an important role in the degradation of phenanthrene and pyrene.