Phenotypic properties and microbial diversity of methanogenic granules from a full-scale UASB reactor treating brewery wastewater

E.E. Diaz, A.J.M. Stams, R. Amils, J.L. Sanz

Research output: Contribution to journalArticleAcademicpeer-review

131 Citations (Scopus)


Methanogenic granules from an anaerobic bioreactor that treated wastewater of a beer brewery consisted of different morphological types of granules. In this study, the microbial compositions of the different granules were analyzed by molecular microbiological techniques: cloning, denaturing gradient gel electrophoresis and fluorescent in situ hybridization (FISH), and scanning and transmission electron microscopy. We propose here that the different types of granules reflect the different stages in the life cycle of granules. Young granules were small, black, and compact and harbored active cells. Gray granules were the most abundant granules. These granules have a multilayer structure with channels and void areas. The core was composed of dead or starving cells with low activity. The brown granules, which were the largest granules, showed a loose and amorphous structure with big channels that resulted in fractured zones and corresponded to the older granules. Firmicutes (as determined by FISH) and Nitrospira and Deferribacteres (as determined by cloning and sequencing) were the predominant Bacteria. Remarkably, Firmicutes could not be detected in the brown granules. The methanogenic Archaea identified were Methanosaeta concilii (70 to 90% by FISH and cloning), Methanosarcina mazei, and Methanospirillum spp. The phenotypic appearance of the granules reflected the physiological condition of the granules. This may be valuable to easily select appropriate seed sludges to start up other reactors.
Original languageEnglish
Pages (from-to)4942-4949
JournalApplied and Environmental Microbiology
Issue number7
Publication statusPublished - 2006


  • in-situ hybridization
  • rna-targeted oligonucleotides
  • gram-positive bacteria
  • dna g+c content
  • physiological-properties
  • methanosarcina-barkeri
  • population dynamics
  • activated-sludge
  • blanket reactor
  • start-up

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