| The genus Massilia is widely found in water,soil,air,plants rhizosphere,phyllosphere and other environments.It has many functions such as participating in carbon and nitrogen cycle,secreting auxin and enzyme,sewage denitrification,dissolving phosphorus,degrading polycyclic aromatic hydrocarbons,and enhancing plant stress resistance.Due to the wide distribution,strong adaptability to the environment,and potential important application value of Massilia strains,its research has gradually attracted people's attention,and it has shown potential application value in soil remediation,enzyme production and secondary metabolites.As a matrix-microbe-plant composite ecosystem,constructed wetland uses the triple synergy of biology,physics and chemistry to remove pollutants.Among them,microorganisms play a vital role.It is driven by microorganisms that the organic pollutants and nitrogen and phosphorus in the sewage are finally degraded and converted into nutrients that can be absorbed by aquatic plants and microorganisms or released into the environment.Studying the composition and ecological function of Massilia in the sewage treatment system of constructed wetlands is of great significance for elucidating the purification mechanism of constructed wetlands and understanding the interaction mechanism between substrates,plants and microorganisms.In this study,the surface flow constructed wetland sewage treatment system was used as the research object.Real-time quantitative PCR,high-throughput sequencing,16S rDNA clone library construction and RFLP methods were used to study the dynamic changes of the composition and quantity of Massilia in the sewage,substrate,rhizosphere,phyllosphere and air of the constructed wetland system for sewage treatment.The correlation between environmental factors and the structure of Massilia species was clarified,and the differences of microbial community structure in air samples from different functional areas and the differences of dominant species of Massilia were clarified.The following results are obtained through research:(1)The 16S rDNA clone library and RFLP sequence analysis were used to analyze the composition of Massilia in the sewage,substrate,rhizosphere,phyllosphere and air of the constructed wetland sewage treatment system.A total of 24 Massilia species were detected in a total of 235 samples,accounting for 55.8%of the found Massilia currently.Among them,there were 5 dominant species(relative abundance of>1%)in different environmental ecological samples,which were M.albidiflava?M.alkalitolerans?M.aurea?M.brevitalea?M.timonae.The number of Massilia species in the constructed wetland sewage treatment system is followed by matrix sample and rhizosphere sample(24)>sewage sample(23)>phyllosphere sample(18)>air sample(16).(2)The relative abundance of M.albidiflava,M.alkalitolerans,M.aurea,M.brevitalea,M.timonae in the sewage,substrate,rhizosphere,phyllosphere and air of constructed artificial wetland showed obvious seasonal differences.The relative abundance of M.alkalitolerans and M.albidiflava was higher in autumn,but lower in summer.The relative abundance of M.aurea and M.brevitalea was higher in spring and summer,but lower in autumn.The relative abundance of M.timonae reached the highest in summer,but was lower in other seasons.(3)Real-time PCR was used to determine the variation of the number of Massilia in constructed wetland wastewater treatment system.The results showed that the number of Massilia in sewage,substrate,plant rhizosphere,phyllosphere and air was significantly different in different growth stages of reeds.Among them,the number of Massilia in the sewage varied from 1.13×105 copies/m L to 2.21×106 copies/m L.The number of Massilia in the substrate varied from 2.57×107 copies/g to 1.00×1010 copies/g.The number of Massilia in plant rhizosphere varied from 1.91×108 copies/g to1.37×1010 copies/g.The number of Massilia in phyllosphere varied from 1.59×106copies/g to 2.21×107 copies/g.The number of Massilia in air varied from 6.90×104copies/m3 to 1.09×106copies/m3.The number of Massilia in sewage,substrate,plant rhizosphere and phyllosphere gradually were less in spring and winter,and more in autumn;The number of Massilia in the air showed a trend of first increasing and then decreasing.There were more Massilia in early autumn,but fewer in spring and winter.There were significant correlations between rhizosphere and substrate,rhizosphere and sewage,sewage and air,sewage and substrate,phyllosphere and air in the quantity of Massilia.(4)RDA(redundancy analysis)method was used to analyze the correlation between the dominant species of Massilia and environmental factors in the constructed wetland wastewater treatment system.The results showed that the dominant species of Massilia in the sewage were mainly affected by NH3-N,T,DO and NO3--N.The dominant species of Massilia in the substrate were mainly affected by T,p H,moisture content,organic matter,TN,TP,and TK.The dominant species of Massilia in the air are mainly affected by humidity,NO2,temperature and SO2.(5)Pearson correlation analysis results show that the correlation between the dominant species of Massilia in substrate,sewage and air was basically consistent.There was a significant negative correlation between M.timonae with M.alkalitolerans and M.albidiflava in constructed wetland sewage treatment system(P<0.01).M.alkalitolerans was significantly positively correlated with M.albidiflava,M.plicata and M.aerilata(P<0.01).M.brevitalea was significantly negatively correlated with M.plicata and M.aerilata(P<0.01).M.plicata and M.aerilata showed a highly significant positive correlation(P<0.01).(6)16S rDNA clone library and high-throughput sequencing were used to compare and analyze the bacterial community structure of constructed wetland and Qingdao urban streets.The results showed that the dominant bacteria genus(>10%)in constructed wetland were mainly Massilia,Pseudomonas and Sphingomonas.Massilia,Acinetobacter and Deinococcus were the main species in urban streets.Four dominant species of Massilia were found in the air bacterial community of constructed wetlands,namely M.brevitalea,M.timonae,M.aurea and M.albidiflava.There were seasonal and regional differences in the composition of the air microbial community in constructed wetlands and urban street functional areas.The proportion of Massilia in constructed wetlands in spring,summer,autumn and winter was 72.13%,20.45%,33.33%and 26.96%,which was higher than that in urban streets,Among them,M.brevitalea,M.aurea and M.aurea had relatively high relative abundance in different seasons(>1%). |
PDF Full Text Request