D-Ribose Interferes with Quorum Sensing to Inhibit Biofilm Formation of Lactobacillus paraplantarum L-ZS9.

Lei Liu,Jinlan Zhang,Ruiyun Wu,Nan Shang,Pinglan Li

doi:10.3389/fmicb.2017.01860

Lei Liu, Jinlan Zhang + Show 3 more

Open Access

https://doi.org/10.3389/fmicb.2017.01860

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Abstract

Biofilms help bacteria survive under adverse conditions, and the quorum sensing (QS) system plays an important role in regulating their activities. Quorum sensing inhibitors (QSIs) have great potential to inhibit pathogenic biofilm formation and are considered possible replacements for antibiotics; however, further investigation is required to understand the mechanisms of action of QSIs and to avoid inhibitory effects on beneficial bacteria. Lactobacillus paraplantarum L-ZS9, isolated from fermented sausage, is a bacteriocin-producing bacteria that shows potential to be a probiotic starter. Since exogenous autoinducer-2 (AI-2) promoted biofilm formation of the strain, expression of genes involved in AI-2 production was determined in L. paraplantarum L-ZS9, especially the key gene luxS. D-Ribose was used to inhibit biofilm formation because of its AI-2 inhibitory activity. Twenty-seven differentially expressed proteins were identified by comparative proteomic analysis following D-ribose treatment and were functionally classified into six groups. Real-time quantitative PCR showed that AI-2 had a counteractive effect on transcription of the genes tuf, fba, gap, pgm, nfo, rib, and rpoN. Over-expression of the tuf, fba, gap, pgm, and rpoN genes promoted biofilm formation of L. paraplantarum L-ZS9, while over-expression of the nfo and rib genes inhibited biofilm formation. In conclusion, D-ribose inhibited biofilm formation of L. paraplantarum L-ZS9 by regulating multiple genes involved in the glycolytic pathway, extracellular DNA degradation and transcription, and translation. This research provides a new mechanism of QSI regulation of biofilm formation of Lactobacillus and offers a valuable reference for QSI application in the future.

Highlights

Bacteria live in dense and diverse communities termed biofilms, which is a major mode of microbial life (Nadell et al, 2016)
Complete genome analysis showed that L. paraplantarum L-ZS9 contains all the genes involved in AI-2 production, including pfs, luxS, metE/metH, metK, and the methyltransferase gene, but sahH or its homologous gene, responsible for changing SAH
AI-2 activity was detected in culture fluid (CF) prepared from L. paraplantarum L-ZS9 grown in skim milk medium and increased with increasing incubation time to reach a maximum value (4864.748 RLUs) after 22 h (Figure 2)

Summary

Introduction

Bacteria live in dense and diverse communities termed biofilms, which is a major mode of microbial life (Nadell et al, 2016). Biofilms are sessile microbial communities that attach to biotic and abiotic surfaces and survive as self-organized, three-dimensional structures by producing an extracellular polymeric matrix (Penesyan et al, 2015). This lifestyle helps microorganisms to survive in unfavorable environments (Taylor et al, 2014; Olsen, 2015). Most research has focused on the regulation of AI-2 in biofilms of pathogens, some non-pathogenic and beneficial bacteria have been reported to use this ‘universal’ and ‘common’ signaling system to regulate their behavior (Park et al, 2016). In Bifidobacteria, AI-2 activity correlates with biofilm formation and gut colonization (Christiaen et al, 2014; Sun et al, 2014)

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