Study On The Diversity And Community Structure Of PAOs In Eutrophication Of Reservoir Sediment

Polyphosphate accummulating organisms(PAOs)play an important role in the phosphorus metabolic cycle in the eutrophic reservoir sediment.Further study of the diversity and community structure of PAOs helps to reveal microbial mechanism of phosphorus metabolic cycle in the eutrophic reservoir sediment.In order to study the diversity and community structure of PAOs in the particular section of sediment of three reservoirs(Jiulongjiangxipi reservoir,Sanshiliujiao lake,Dongyaxi reservoir)in Fujian province,the molecular biology methods combined with the determination of the physical and chemical index were used in this paper.In order to analyze the physical and chemical indexes of the water and different forms of phosphorus in the sediment,the field and laboratory methods were combined.It showed that TP in the three reservoirs were 1361.6±9.1mg/kg,563.9±8.6mg/kg,599.1 ±6.4mg/kg,respectively.The percentages of active phosphorus Fe/Al-P and OP accounted for 61.7%,78.7%,67.6%in the sediments of the three reservoirs,Sanshiliujiao lake has the highest potential for phosphorus release.The Sanshiliujiao lake was considered as seasonal dynamic research object.The results showed that the TP of S3 sediments and S1 sediments in summer were 512.3±7.2 mg/kg,362.1±7.4mg/kg,respectively.The TP of S3 sediments and S1 sediments in winter were 522.9 ± 7.0mg/kg,503.7 ± 2.3mg/kg,respectively.The overall trend of different forms of phosphorus from summer to winter varied from obvious to similarity.The contents of Fe/Al-P and OP in the two sites were decreased from 79.6%,79.8%in summer to 73.2%,71.7%in winter,and the potential of phosphorus release became smaller.The sediment samples in 3 reservoir center points and 0 to 2cm columnar samples of important points(S1 and S3)in Sanshiliujiao lake reservoir were used as study object.The space-time distribution patterns of diversity of PAOs were detectd by terminal restriction fragment length polymorphism(T-RFLP)method.The results showed that diversity varied from different reservoirs in center points sediments.The community structure of PAOs in Sanshiliujiao lake reservoir was most complicated.But the dominant T-RFs fragments of three reservoirs were all between 220 bp to 260 bp,besides,the groups of PAOs represented by 223 bp and 237 bp were all exist in 3 reservoirs,and the proportion of 237 bp in different samples was similar.The differences of diversity of PAOs were more apparent in different seasons than in different space.The dominant T-RFs segments concentrated in the range 200 bp to 300 bp in summer,while concentrated in the range 150 bp to 200 bp in winter.Except for 181 bp presented in both S1 and S3 in winter and S1 in the summer,with relative abundance all reached 25%,other fragments were not detected at the same time in different seasons.The community structure of PAOs in sediment samples of 3 reservoir center points were analyzed by PCR-RFLP and clone sequencing methods.The results showed that PAOs in sediment samples of Jiulongjiangxipi reservoir included 9 phylum and 19 genera,PAOs in sediment samples of Sanshiliujiao lake included 11 phylum and 24 genera,PAOs in sediment samples of Dongyaxi reservoir includes 9 phylum and 18 genera.Community structure of PAOs in Sanshiliujiao lake was most complicated,which was consistented with the results of the T-RFLP.The differences of dominant PAOs in 3 reservoir are obvious,but mainly concentrated in the Proteobacteria,Actinobacteria and Acidobacteria.The percentage of this three phylum accounted for 74.5%,74.5%and 74.5%respectively in 3 reservoir.The dominant groups existed in all reservoir sediment samples were only Anaeromyxobacter and Solibacter.