Beginning a molecular analysis of the eukaryal community in activated sludge

Terence L. Marsh, Wen Tso Liu, Larry J. Forney, Hans Cheng

Research output: Contribution to journalConference articlepeer-review


As a means to furthering our understanding of the eukaryal community in activated sludge, we have applied contemporary molecular techniques to an activated sludge community maintained in a laboratory-scale bioreactor. The initial inoculum was derived from a local wastewater treatment facility in East Lansing, MI and maintained with continuous aeration and a daily feeding regime that included glucose and peptone. Samples were taken on a weekly basis for 5 weeks and community DNA was extracted from 2-5 ml of activated sludge. Using a variety of oligonucleotide primers specific to eukaryotic small subunit ribosomal DNA, we PCR amplified rDNA from the total community DNA. PCR products were analyzed by three techniques, denaturing gradient gel electrophoresis (DGGE), terminal restriction fragment length polymorphism (T-RFLP) and comparative sequence analysis of rDNA clones. Over the course of 5 weeks, analysis with DGGE revealed dramatic changes in the eukaryotic community based on differences in denaturation profiles, However, the analysis is limited to 5-6 bands corresponding to 5-6 different 'ribotypes'. Analysis with T-RFLP also suggests changes to the eukaryotic community over time. Both increases and decreases in population size can be detected as a function of time. Up to 15 different terminal restriction fragments can be detected with T-RFLP indicating that this technique is considerably more sensitive than DGGE. Phylogenetic analysis of partial sequences from 11 cloned rDNAs indicate that all 11 clones are from the Ciliophora phylum.

Original languageEnglish (US)
Pages (from-to)455-460
Number of pages6
JournalWater Science and Technology
Issue number4-5
StatePublished - 1998
Externally publishedYes
EventProceedings of the 1997 2nd International Conference on Microorganisms in Activated Sludge and Biofilm Processes - Berkeley, CA, USA
Duration: Jul 21 1997Jul 23 1997


  • Activated sludge
  • DGGE
  • Diversity
  • Eukaryotes
  • Phylogeny
  • T-RFLP
  • Terminal restriction fragment length polymorphism

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology


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