Change in the community structure of ammonia-oxidizing bacteria in activated sludge during selective incubation for MPN determination

Kayako Hirooka, Ryoki Asano, Yutaka Nakai

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

We investigated the changes in the community structure of ammonia-oxidizing bacteria (AOB) in activated sludge during incubation of the sludge in a medium selective for AOB. The number of AOB present in the activated sludge sample was enumerated by the most-probable-number (MPN) method. Both the activated sludge sample and the incubated samples for MPN determination were analyzed by polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE). Universal PCR-DGGE indicated that even after 40-d incubation in a medium selected for AOB, the MPN samples were predominantly composed of heterotrophic bacteria and not AOB. Denitrification by heterotrophic bacteria might lead to the underestimation of the MPN count of AOB. Not dominated in whole bacteria, one species of AOB was detected in both original activated sludge and samples after MPN incubation by PCR-DGGE targeting AOB. Furthermore, two new species of AOB were detected only after incubation. Therefore, the community structure of AOB in the MPN samples partially resembled that in the original activated sludge.

Original languageEnglish
Pages (from-to)679-685
Number of pages7
JournalJournal of Industrial Microbiology and Biotechnology
Volume36
Issue number5
DOIs
Publication statusPublished - 2009 May 1

Keywords

  • Ammonia-oxidizing bacteria
  • Microbial community structure
  • Most-probable-number (MPN) method
  • Polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE)

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology

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