Journal of Microbiology

Journal Article

A common evolutionary pathway for maintaining quorum sensing in Pseudomonas aeruginosa: Bai-min Lai , Hui-cong Yan , Mei-zhen Wang , Na Li , Dong-sheng Shen; J. Microbiol. 2018;56(2):83-89. Published online February 2, 2018; DOI: https://doi.org/10.1007/s12275-018-7286-1

Abstract: In the bacterium Pseudomonas aeruginosa, the synthesis and secretion of extracellular protease is a typical cooperative behavior regulated by quorum sensing. However, this type of cooperative behavior is easily exploited by other individuals who do not synthesize public goods, which is known as the “tragedy of the commons”. Here P. aeruginosa was inoculated into casein media with different nitrogen salts added. In casein broth, protease (a type of public good) is necessary for bacterial growth. After 30 days of sequential transfer, some groups propagated stably and avoided “tragedy of the commons”. The evolved cooperators who continued to synthesize protease were isolated from these stable groups. By comparing the characteristics of quorum sensing in these cooperators, an identical evolutionary pattern was found. A variety of cooperative behaviors regulated by quorum sensing, such as the synthesis and secretion of protease and signals, were significantly reduced during the process of evolution. Such reductions improved the efficiency of cooperation, helping to prevent cheating. In addition, the production of pyocyanin, which is regulated by the RhlIR system, increased during the process of evolution, possibly due to its role in stabilizing the cooperation. This study contributes towards our understanding of the evolution of quorum sensing of P. aeruginosa.

Research Support, Non-U.S. Gov'ts

Note] Inhibition of quorum sensing in Pseudomonas aeruginosa by two herbal essential oils from Apiaceae family: Ehsan Sepahi , Saeed Tarighi , Farajollah Shahriari Ahmadi , Abdolreza Bagheri; J. Microbiol. 2015;53(2):176-180. Published online January 5, 2015; DOI: https://doi.org/10.1007/s12275-015-4203-8

Abstract: Ferula (Ferula asafoetida L.) and Dorema (Dorema aucheri Bioss.) both from Apiaceae family were tested for their antiquorum sensing (QS) activity against Pseudomonas aeruginosa. Both essential oils exhibited anti-QS activity at 25 μg/ml of concenteration. At this concenteration Ferula fully abolished and Dorema reduced the violacein production by C. violaceum. Pyocyanin, pyoverdine, elastase and biofilm production were decreased in Ferula oil treatments. Dorema oil reduced pyoverdine and elastase production, while pyocyanin and biofilm production were not affacted. Expresion analysis of QS-dependent genes confirmed our phenotypic data. Our data introduced native Dorema and Ferula plants as novel QS and virulence inhibitors.

Inhibitory Effects of 4-Hydroxy-2,5-Dimethyl-3(2H)-Furanone (HDMF) on Acyl-Homoserine Lactone-Mediated Virulence Factor Production and Biofilm Formation in Pseudomonas aeruginosa PAO1: Sung-Chan Choi , Can Zhang , Sooyoung Moon , Young-Sook Oh; J. Microbiol. 2014;52(9):734-742. Published online August 2, 2014; DOI: https://doi.org/10.1007/s12275-014-4060-x

Abstract: 4-Hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF), a nonhalogenated furanone found in a variety of fruits, has been shown to have antimicrobial activity. However, few studies have focused on its inhibitory effect on bacterial quorum sensing (QS) at levels below the non-inhibitory concentration. In this study, 0.1 μM HDMF decreased the production of QS signal molecules and inhibited QS-controlled biofilm formation by Pseudomonas aeruginosa PAO1 without causing growth inhibition. In the presence of 0.1 and 1.0 μM HDMF, biofilm production by PAO1 was reduced by 27.8 and 42.6%, respectively, compared to that by untreated control cells. HDMF (1.0 μM) also significantly affected virulence factor expression (regulated by the las, rhl, and pqs system), resulting in a significant reduction in the production of LasA protease (53.8%), rhamnolipid (40.9%), and pyocyanin (51.4%). This HDMF-dependent inhibition of virulence factor expression was overcome by increasing the levels of two QS signal molecules of P. aeruginosa, N-(3-oxo-dodecanoyl)-L-homoserine lactone and N-butyryl-L-homoserine lactone, suggesting reversible competitive inhibition between HDMF and these molecules. The results of this study indicate that HDMF has great potential as an inhibitor of QS, and that it may be of value as a therapeutic agent and in biofilm control, without increasing selective pressure for resistance development.

Acyl-Homoserine Lactone Quorum Sensing in Bacteria: E. Peter Greenberg; J. Microbiol. 2000;38(3):117-121.

Abstract: Recent advances in studies of bacterial gene expression and light microscopy show that cell-to-cell communication and community behavior are the rule rather than the exception. One type of cell-cell communication, quorum sensing in Gram-negative bacteria involves acyl-homoserine lactone signals. This type of quorum sensing represents a dedicated communication system that enables a given species to sense when it has reached a critical population density, and to respond by activating expression of specific genes. The LuxR and LuxI proteins of Vibrio fisheri are the founding members of the acyl-homoserine lactone quorum sensing signal receptor and signal generator families of proteins. Acyl-homoserine lactone signaling in Pseudomonas aeruginosa is one model for the relationship between quorum sensing, community behavior, and virulence. In the P. aeruginosa model, quorum sensing is required for normal biofilm maturation and virulence. There are multiple quorum-sensing circuits that control the expression of dozens of specific genes in P. aeruginosa.

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