Quorum sensing between Gram-negative bacteria responsible for methane production in a complex waste sewage sludge consortium

Phuong Dong Thi Nguyen, Nurul Asyifah Mustapha, Kiwao Kadokami, Rodolfo Garcia-Contreras, Thomas K. Wood, Toshinari Maeda

Research output: Contribution to journalArticle

3 Scopus citations


Quorum sensing (QS) plays a key role in activating bacterial functions through small molecules called autoinducers. In this study, the QS of Gram-negative bacteria in waste sewage sludge (WSS) was downregulated by adding the quorum quenching enzyme, AiiM lactonase, which cleaved the acyl-homoserine lactone (AHL) autoinducer signals from Gram-negative bacteria, and subsequently methane production was inhibited by over 400%. The pH was lowered after 2 days in the anaerobic fermentation whereas protease activity at the hydrolysis step was almost the same with or without AiiM. The production of acetic acid significantly increased during the fermentation in the presence of AiiM. The bacterial community at day 2 indicated that the population of Gram-positive bacteria increased in the presence of AiiM, and the percentage of Gram-negative bacteria decreased in the WSS containing AiiM. The change in the bacterial community in the presence of AiiM may be due to the different antimicrobial agents produced in the WSS because some of the Gram-positive bacteria were killed by adding the solid-phase extraction (SPE) fraction from the WSS without AiiM. In contrast, the SPE fraction with AiiM had reduced bactericidal activity against Gram-negative bacteria. Thus, bacterial signaling between Gram-negative bacteria is critical for methane production by the microbial consortia.

Original languageEnglish (US)
Pages (from-to)1485-1495
Number of pages11
JournalApplied Microbiology and Biotechnology
Issue number3
StatePublished - Feb 1 2019


All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Applied Microbiology and Biotechnology

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