The Effect of Initial Inoculum Source on the Microbial Community Structure and Dynamics in Laboratory-Scale Sequencing Batch Reactors

Handle URI:
http://hdl.handle.net/10754/209382
Title:
The Effect of Initial Inoculum Source on the Microbial Community Structure and Dynamics in Laboratory-Scale Sequencing Batch Reactors
Authors:
Hernandez, Susana
Abstract:
Understanding the factors that shapes the microbial community assembly in activated sludge wastewater treatment processes provide a conceptual foundation for improving process performance. The aim of this study was to compare two major theories (deterministic theory and neutral theory) regarding the assembly of microorganisms in activated sludge: Six lab-scale activated sludge sequencing batch reactors were inoculated with activated sludge collected from three different sources (domestic, industrial, and sugar industry WWTP). Additionally, two reactors were seeded with equal proportion of sludge from the three WWTPs. Duplicate reactors were used for each sludge source (i.e. domestic, industrial, sugar and mix). Reactors were operated in parallel for 11 weeks under identical conditions. Bacterial diversity and community structure in the eight SBRs were assessed by 16S rRNA gene pyrosequencing. The 16S rRNA gene sequences were analyzed using taxonomic and clustering analysis and by measuring diversity indices (Shannon-weaver and Chao1 indices). Cluster analysis revealed that the microbial community structure was dynamic and that replicate reactors evolved differently. Also the microbial community structure in the SBRs seeded with a different sludge did not converge after 11 weeks of operation under identical conditions. These results suggest that history and distribution of taxa in the source inoculum were stronger regulating factors in shaping bacterial community structure than environmental factors. This supports the neutral theory which states that the assembly of the local microbial community from the metacommunity is random and is regulated by the size and diversity of the metacommunity. Furthermore, sludge performance, measured by COD and ammonia removal, confirmed that broad-scale functions (e.g. COD removal) are not influenced by dynamics in the microbial composition, while specific functions (e.g. nitrification) are more susceptible to these changes.
Advisors:
Saikaly, Pascal E.
Committee Member:
Drewes, Jörg E.
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Program:
Chemical and Biological Engineering
Issue Date:
Jul-2011
Type:
Thesis
Appears in Collections:
Theses; Physical Sciences and Engineering (PSE) Division; Chemical and Biological Engineering Program

Full metadata record

DC FieldValue Language
dc.contributor.advisorSaikaly, Pascal E.en
dc.contributor.authorHernandez, Susanaen
dc.date.accessioned2012-02-04T08:32:23Z-
dc.date.available2012-02-04T08:32:23Z-
dc.date.issued2011-07en
dc.identifier.urihttp://hdl.handle.net/10754/209382en
dc.description.abstractUnderstanding the factors that shapes the microbial community assembly in activated sludge wastewater treatment processes provide a conceptual foundation for improving process performance. The aim of this study was to compare two major theories (deterministic theory and neutral theory) regarding the assembly of microorganisms in activated sludge: Six lab-scale activated sludge sequencing batch reactors were inoculated with activated sludge collected from three different sources (domestic, industrial, and sugar industry WWTP). Additionally, two reactors were seeded with equal proportion of sludge from the three WWTPs. Duplicate reactors were used for each sludge source (i.e. domestic, industrial, sugar and mix). Reactors were operated in parallel for 11 weeks under identical conditions. Bacterial diversity and community structure in the eight SBRs were assessed by 16S rRNA gene pyrosequencing. The 16S rRNA gene sequences were analyzed using taxonomic and clustering analysis and by measuring diversity indices (Shannon-weaver and Chao1 indices). Cluster analysis revealed that the microbial community structure was dynamic and that replicate reactors evolved differently. Also the microbial community structure in the SBRs seeded with a different sludge did not converge after 11 weeks of operation under identical conditions. These results suggest that history and distribution of taxa in the source inoculum were stronger regulating factors in shaping bacterial community structure than environmental factors. This supports the neutral theory which states that the assembly of the local microbial community from the metacommunity is random and is regulated by the size and diversity of the metacommunity. Furthermore, sludge performance, measured by COD and ammonia removal, confirmed that broad-scale functions (e.g. COD removal) are not influenced by dynamics in the microbial composition, while specific functions (e.g. nitrification) are more susceptible to these changes.en
dc.language.isoenen
dc.titleThe Effect of Initial Inoculum Source on the Microbial Community Structure and Dynamics in Laboratory-Scale Sequencing Batch Reactorsen
dc.typeThesisen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen_GB
dc.contributor.committeememberDrewes, Jörg E.en
thesis.degree.disciplineChemical and Biological Engineeringen
thesis.degree.nameMaster of Scienceen
dc.person.id101987en
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