A Study On The Microbial Characteristics Of A Fluidized-pellet-bed Biareactor

To reveal microbial characteristic of a Fluidized-pellet-bed (FPB) bioreactor, sludge and supernatant in different heights (10cm, 60cm and 110cm) of FPB were sampled after depositing for 20min. Through bacterial cultivation, the total aerobic bacteria counts, denitrifyimg bacteria counts and devulcanizating bacteria counts along the height of FPB were detected. Meanwhile, the molecular biology method was also used to study on the microbial characteristic of a Fluidized-pellet-bed (FPB) bioreactor.The genomic DNA of microbial community was extracted directly through cells decomposition, and then amplified with the universal primers of Eubacteria and Archaebacteria (530F and 1490R). These amplified DNA fragments about 1kb were purified and then separated by denaturing gradient gel electrophoresis (DGGE) with the denaturant (urea and formamide) concentration from 30% to 60%. From that, DNA characteristic fingerprint spectrogram was got. And then, the characteristic bands of DGGE were sequenced and the phylogenetic diversity of microorganisms in the FPB bioreactor was surveyed based on the homology analysis of 16S rRNA sequences.The result of bacterial cultivation reveals that from the bottom to the top of the FPB column the total aerobic bacteria count is very abundant, especially in the bottom of the reactor. Meanwhile, some facultative anaerobe such as denitrifyimg bacteria and obligate anaerobe like devulcanizating bacteria also exsited in the FPB reactor.Through PCR-DGGE detection, we get the results that there are 23 kinds of microorganisms at the height of 10 cm, 21 kinds at 60 cm and 20 kinds at 110 cm. Meanwhile, specific microorganisms and common microorganisms are both found in different height of FPB bioreactor. However, the succession of microorganism communities in different height of the reactor is not very obvious. The comparability of the microorganism communities at the bottom, the middle and the upside of the reactor is 83.1%. It means that the structure of the microorganism communities was very stable.16S rRNA sequence analysis indicates that 18 operational taxonomic units (OTUs) which we have got all belong to Eubacteria. Among them, 61% (11/18) is Proteobacteria, 17 % (3/18) is Actinobacteria, 11% (2/18) is low G+C gram-positive bacterium and 11% (2/18) belongs to other bacteria branches.