title: Microbial selection pressure is not a prerequisite for granulation: dynamic granulation and microbial community study in a complete mixing bioreactor.
abstract: Microbial selection pressure is traditionally supposed as a prerequisite for aerobic granulation. This work gives a different insight on this issue. Fluorescent microspheres were used to label the flocculent biomass granulation for a period of 47days in a continuous-flow bioreactor. Analysis of the distribution of fluorescent microspheres in granules revealed that the terminal phase of granulation is in a dynamic steady state, where bioflocs detach, collide and aggregate randomly. This revealed that the un-granulated biomass was the result of the dynamic aggregation and breakage, rather than the microbial species unable to be granulated. Furthermore, denaturing gradient gel electrophoresis (DGGE) profile and UPGMA dendrogram results showed similar microbial communities during the granulation. To sum up, microbial selection pressure was not a prerequisite for aerobic granulation from both of the dynamic granulation steps and molecular biology aspects.
authors.affiliation: Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, China.
authors.forename: Dandan
authors.initials: D
authors.lastname: Zhou
authors.affiliation: Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, China.
authors.forename: Shu
authors.initials: S
authors.lastname: Niu
authors.affiliation: Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, China.
authors.forename: Yongjiao
authors.initials: Y
authors.lastname: Xiong
authors.affiliation: Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Key Lab of Groundwater Resources and Environment, Ministry of Education, Jilin University, Changchun 130021, China. Electronic address: dongshuangshi@gmail.com.
authors.forename: Shuangshi
authors.initials: S
authors.lastname: Dong
mesh_terms: D000332:Aerobiosis; D019149:Bioreactors; D059013:Microbial Consortia / Q000502:physiology*; D012641:Selection, Genetic
keywords: Aerobic granules; Fluorescent microsphere; Granulation process; Microbial community; Microbial selection pressure