Journal of Microbiology

Journal Article

Quorum Quenching Potential of Reyranella sp. Isolated from Riverside Soil and Description of Reyranella humidisoli sp. nov.: Dong Hyeon Lee, Seung Bum Kim; J. Microbiol. 2024;62(6):449-461. Published online May 30, 2024; DOI: https://doi.org/10.1007/s12275-024-00131-2

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Quorum quenching refers to any mechanism that inhibits quorum sensing processes. In this study, quorum quenching activity among bacteria inhabiting riverside soil was screened, and a novel Gram-stain-negative, rod shaped bacterial strain designated MMS21-HV4-11(T), which showed the highest level of quorum quenching activity, was isolated and subjected to further analysis. Strain MMS21-HV4-11(T) could be assigned to the genus Reyranella of Alphaproteobacteria based on the 16S rRNA gene sequence, as the strain shared 98.74% sequence similarity with Reyranella aquatilis seoho-37(T), and then 97.87% and 97.80% sequence similarity with Reyranella soli KIS14-15(T) and Reyranella massiliensis 521(T), respectively. The decomposed N-acyl homoserine lactone was restored at high concentrations under acidic conditions, implying that lactonase and other enzyme(s) are responsible for quorum quenching. The genome analysis indicated that strain MMS21-HV4-11(T) had two candidate genes for lactonase and one for acylase, and expected protein structures were confirmed. In the quorum sensing inhibition assay using a plant pathogen Pectobacterium carotovorum KACC 14888, development of soft rot was significantly inhibited by strain MMS21-HV4-11(T). Besides, the swarming motility by Pseudomonas aeruginosa PA14 was significantly inhibited in the presence of strain MMS21-HV4-11(T). Since the isolate did not display direct antibacterial activity against either of these species, the inhibition was certainly due to quorum quenching activity. In an extended study with the type strains of all known species of Reyranella, all strains were capable of degrading N-acyl homoserine lactones (AHLs), thus showing quorum quenching potential at the genus level. This is the first study on the quorum quenching potential and enzymes responsible in Reyranella. In addition, MMS21-HV4-11(T) could be recognized as a new species through taxonomic characterization, for which the name Reyranella humidisoli sp. nov. is proposed (type strain = MMS21-HV4-11( T) = KCTC 82780( T) = LMG 32365(T)).

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Study of N-acyl homoserine lactone (AHL) degradation potential of bacteria isolated from environmental samples and their impact on quorum sensing regulated biofilm formation of Pseudomonas aeruginosa
Anju Tomy, Rakesh Yasarla
Journal of Environmental Chemical Engineering.2025; 13(2): 115974. CrossRef
Research progress of bacterial quorum sensing systems in synthetic biology applications
Boyu Luo, Tuoyu Liu, Zhi Sun, Yue Teng
Chinese Science Bulletin.2024; 69(36): 5213. CrossRef
Validation List no. 220. Valid publication of new names and new combinations effectively published outside the IJSEM
Aharon Oren, Markus Göker
International Journal of Systematic and Evolutionary Microbiology .2024;[Epub] CrossRef

Research Support, Non-U.S. Gov't

D101 is critical for the function of AttJ, a repressor of quorum quenching system in Agrobacterium tumefaciens: Chao Wang , Chunlan Yan , Yong-Gui Gao , Lian-Hui Zhang; J. Microbiol. 2015;53(9):623-632. Published online August 1, 2015; DOI: https://doi.org/10.1007/s12275-015-5100-x

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Abstract: The quorum quenching system of Agrobacterium tumefaciens is specifically activated upon entering the stationary phase. Evidence has shown that this system includes two key components: the IclR-type transcriptional factor AttJ (also named as BlcR) and the AHL-lactonase AttM (also named as BlcC). At exponential phase, AttJ binds to the promoter region of attM and thus suppresses the expression of attM. At stationary phase, however, the small molecule SSA directly binds to AttJ and relieves its inhibition of AttJ and thereby triggers the expression of attM. While the regulation of AttM has been extensively investigated, little is known about the regulation of AttJ. In this study, we demonstrated the D101 amino acid of AttJ is essential for the AttJ function. In vitro, the variant protein of AttJD101H appeared to be readily aggregated. In vivo, the D101H mutation in AttJ entirely abolished the inhibitory activity of AttJ and overexpressed attM in A. tumefaciens A6. In addition, D101H mutation led to an overexpression of attJ, indicating an auto-regulatory mechanism for the attJ regulation. Put together, these findings demonstrate that D101 is an important amino acid for the transcription activity of AttJ and the transcription of attJ is regulated by a negative feedback loop. These results expand previous biochemical characterization of AttJ and provide new mechanistic insights into the regulation of quorum quenching in A. tumefaciens.

Quorum Sensing and Quorum-Quenching Enzymes: Yi-Hu Dong , Lian-Hui Zhang; J. Microbiol. 2005;43(1):101-109.

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Abstract: To gain maximal benefit in a competitive environment, single-celled bacteria have adopted a community genetic regulatory mechanism, known as quorum sensing (QS). Many bacteria use QS signaling systems to synchronize target gene expression and coordinate biological activities among a local population. N-acylhomoserine lactones (AHLs) are one family of the well-characterized QS signals in Gram-negative bacteria, which regulate a range of important biological functions, including virulence and biofilm formation. Several groups of AHL-degradation enzymes have recently been identified in a range of living organisms, including bacteria and eukaryotes. Expression of these enzymes in AHL-dependent pathogens and transgenic plants efficiently quenches the microbial QS signaling and blocks pathogenic infections. Discovery of these novel quorum quenching enzymes has not only provided a promising means to control bacterial infections, but also presents new challenges to investigate their roles in host organisms and their potential impacts on ecosystems.

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