Dataset Information

Reducing Quorum Sensing-Mediated Virulence Factor Expression and Biofilm Formation in Hafnia alvei by Using the Potential Quorum Sensing Inhibitor L-Carvone.

ABSTRACT: Quorum sensing (QS), one of the most remarkable microbiological discoveries, is considered a global gene regulatory mechanism for various traits in bacteria, including virulence and spoilage. Hafnia alvei, an opportunistic pathogen and a dominant psychrophile, uses the lux-type QS system to regulate the production of virulence factors and biofilms, which are harmful to the food industry. Based on the QS interference approach, this study aimed to reveal the efficacy of L-carvone at sublethal concentrations on QS-regulated virulence factors and biofilm formation in H. alvei. QS inhibitory activity was demonstrated by the reduction in swinging motility (61.49%), swarming motility (74.94%), biofilm formation (52.41%) and acyl-homoserine lactone (AHL) production (0.5 ?L/mL). Additionally, in silico analysis and RT-qPCR studies for AHL synthase HalI and QS transcriptional regulator HalR revealed a plausible molecular mechanism for QS inhibition by L-carvone. These findings suggest that L-carvone (a main component of spearmint essential oils) could be used as a novel quorum sensing inhibitor to control H. alvei in the food industry.

SUBMITTER: Li T

PROVIDER: S-EPMC6334668 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Reducing Quorum Sensing-Mediated Virulence Factor Expression and Biofilm Formation in Hafnia alvei by Using the Potential Quorum Sensing Inhibitor L-Carvone.

Li Tingting T Mei Yongchao Y He Binbin B Sun Xiaojia X Li Jianrong J

Frontiers in microbiology 20190109

Quorum sensing (QS), one of the most remarkable microbiological discoveries, is considered a global gene regulatory mechanism for various traits in bacteria, including virulence and spoilage. Hafnia alvei, an opportunistic pathogen and a dominant psychrophile, uses the lux-type QS system to regulate the production of virulence factors and biofilms, which are harmful to the food industry. Based on the QS interference approach, this study aimed to reveal the efficacy of L-carvone at ...[more]

PMID: 30687295

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Project description:Acinetobacter baumannii possesses a single divergent luxR/luxRI-type quorum-sensing (QS) locus named abaR/abaI This locus also contains a third gene located between abaR and abaI, which we term abaM, that codes for an uncharacterized member of the RsaM protein family known to regulate N-acylhomoserine lactone (AHL)-dependent QS in other beta- and gammaproteobacteria. Here, we show that disruption of abaM via a T26 insertion in A. baumannii strain AB5075 resulted in increased production of N-(3-hydroxydodecanoyl)-l-homoserine lactone and enhanced surface motility and biofilm formation. In contrast to the wild type and the abaI::T26 mutant, the virulence of the abaM::T26 mutant was completely attenuated in a Galleria mellonella infection model. Transcriptomic analysis of the abaM::T26 mutant revealed that AbaM differentially regulates at least 76 genes, including the csu pilus operon and the acinetin 505 lipopeptide biosynthetic operon, that are involved in surface adherence, biofilm formation and virulence. A comparison of the wild type, abaM::T26 and abaI::T26 transcriptomes, indicates that AbaM regulates ∼21% of the QS regulon including the csu operon. Moreover, the QS genes (abaI and abaR) were among the most upregulated in the abaM::T26 mutant. A. baumannii lux-based abaM reporter gene fusions revealed that abaM expression is positively regulated by QS but negatively autoregulated. Overall, the data presented in this work demonstrates that AbaM plays a central role in regulating A. baumannii QS, virulence, surface motility, and biofilm formation.IMPORTANCE Acinetobacter baumannii is a multiantibiotic-resistant pathogen of global health care importance. Understanding Acinetobacter virulence gene regulation could aid the development of novel anti-infective strategies. In A. baumannii, the abaR and abaI genes that code for the receptor and synthase components of an N-acylhomoserine (AHL) lactone-dependent quorum sensing system (QS) are separated by abaM Here, we show that although mutation of abaM increased AHL production, surface motility, and biofilm development, it resulted in the attenuation of virulence. AbaM was found to control both QS-dependent and QS-independent genes. The significance of this work lies in the identification of AbaM, an RsaM ortholog known to control virulence in plant pathogens, as a modulator of virulence in a human pathogen.

Project description:BACKGROUND: In a previous study, we demonstrated that Vibrio scophthalmi, the most abundant Vibrio species among the marine aerobic or facultatively anaerobic bacteria inhabiting the intestinal tract of healthy cultured turbot (Scophthalmus maximus), contains at least two quorum-sensing circuits involving two types of signal molecules (a 3-hydroxy-dodecanoyl-homoserine lactone and the universal autoinducer 2 encoded by luxS). The purpose of this study was to investigate the functions regulated by these quorum sensing circuits in this vibrio by constructing mutants for the genes involved in these circuits. RESULTS: The presence of a homologue to the Vibrio harveyi luxR gene encoding a main transcriptional regulator, whose expression is modulated by quorum-sensing signal molecules in other vibrios, was detected and sequenced. The V. scophthalmi LuxR protein displayed a maximum amino acid identity of 82% with SmcR, the LuxR homologue found in Vibrio vulnificus. luxR and luxS null mutants were constructed and their phenotype analysed. Both mutants displayed reduced biofilm formation in vitro as well as differences in membrane protein expression by mass-spectrometry analysis. Additionally, a recombinant strain of V. scophthalmi carrying the lactonase AiiA from Bacillus cereus, which causes hydrolysis of acyl homoserine lactones, was included in the study. CONCLUSIONS: V. scophthalmi shares two quorum sensing circuits, including the main transcriptional regulator luxR, with some pathogenic vibrios such as V. harveyi and V. anguillarum. However, contrary to these pathogenic vibrios no virulence factors (such as protease production) were found to be quorum sensing regulated in this bacterium. Noteworthy, biofilm formation was altered in luxS and luxR mutants. In these mutants a different expression profile of membrane proteins were observed with respect to the wild type strain suggesting that quorum sensing could play a role in the regulation of the adhesion mechanisms of this bacterium.

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Dataset Information

Reducing Quorum Sensing-Mediated Virulence Factor Expression and Biofilm Formation in Hafnia alvei by Using the Potential Quorum Sensing Inhibitor L-Carvone.

Publications

Reducing Quorum Sensing-Mediated Virulence Factor Expression and Biofilm Formation in <i>Hafnia alvei</i> by Using the Potential Quorum Sensing Inhibitor L-Carvone.

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