title: Strain identification and quorum sensing inhibition characterization of marine-derivedRhizobiumsp. NAO1.
abstract: A novel strategy for combating pathogens is through the ongoing development and use of anti-quorum sensing (QS) treatments such as therapeutic bacteria or their anti-QS substances. Relatively little is known about the bacteria that inhabit the open ocean and of their potential anti-pathogenic attributes; thus, in an initiative to identify these types of therapeutic bacteria, planktonic microbes from the North Atlantic Ocean were collected, isolated, cultured and screened for anti-QS activity. Screening analysis identified one such strain,Rhizobiumsp. NAO1. Extracts ofRhizobiumsp. NAO1 were identified via ultra-performance liquid chromatography (UPLC) analysis. They were shown to containN-acyl homoserine lactone (AHL)-based QS analogues (in particular, theN-butyryl homoserine lactone (C4-AHL) analogue) and could disrupt biofilm formation byPseudomonas aeruginosaPAO1. QS inhibition was confirmed using confocal scanning laser microscopy and growth curves, and it was shown to occur in a dose-dependent manner without affecting bacterial growth. Secondary metabolites ofRhizobiumsp. NAO1 inhibited PAO1 pathogenicity by downregulating AHL-mediated virulence factors such as elastase activity and siderophore production. Furthermore, as a result of biofilm structure damage, the secondary metabolite products ofRhizobiumsp. NAO1 significantly increased the sensitivity of PAO1 to aminoglycoside antibiotics. Our results demonstrated thatRhizobiumsp. strain NAO1 has the ability to disruptP. aeruginosaPAO1 biofilm architecture, in addition to attenuatingP. aeruginosaPAO1 virulence factor production and pathogenicity. Therefore, the newly identified ocean-derivedRhizobiumsp. NAO1 has the potential to serve as a QS inhibitor and may be a new microbial resource for drug development.
authors.affiliation: School of Life Science, Tsinghua University, Beijing 100081, People's Republic of China; Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Shenzhen, Guangdong Province 518055, People's Republic of China.
authors.forename: Hong
authors.initials: H
authors.lastname: Chang
authors.affiliation: Shenzhen Public Platform for Screening and Application of Marine Microbial Resources , Shenzhen, Guangdong Province 518055 , People's Republic of China.
authors.forename: Jin
authors.identifier: 0000-0003-0372-2554
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Shenzhen Public Platform for Screening and Application of Marine Microbial Resources , Shenzhen, Guangdong Province 518055 , People's Republic of China.
authors.forename: Xiaoshan
authors.initials: X
authors.lastname: Zhu
authors.affiliation: School of Life Science, Tsinghua University, Beijing 100081, People's Republic of China; Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Shenzhen, Guangdong Province 518055, People's Republic of China.
authors.forename: Shenchen
authors.initials: S
authors.lastname: Yu
authors.affiliation: School of Life Science, Tsinghua University, Beijing 100081, People's Republic of China; Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Shenzhen, Guangdong Province 518055, People's Republic of China.
authors.forename: Lu
authors.initials: L
authors.lastname: Chen
authors.affiliation: School of Life Science, Tsinghua University, Beijing 100081, People's Republic of China; Shenzhen Public Platform for Screening and Application of Marine Microbial Resources, Shenzhen, Guangdong Province 518055, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Jin
authors.affiliation: Shenzhen Public Platform for Screening and Application of Marine Microbial Resources , Shenzhen, Guangdong Province 518055 , People's Republic of China.
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Cai
keywords: Rhizobium sp. NAO1; biofilm; open ocean; quorum sensing inhibition; virulence factors