Assessment of the anti-quorum sensing effect of Lactobacillus sp. metabolites on expression levels of QS-related genes in Pseudomonas aeruginosa PAO1 Pseudomonas aeruginosa PAO1'de QS ilişkili genlerin ekspresyon seviyeleri üzerine Lactobacillus sp. metabolitlerinin anti-quorum sensing etkilerinin belirlenmesi Didem KART 1 , Suna Sibel GÜRPINAR 2 , Müjde ERYILMAZ 2 ÖZET Amaç: Pseudomonas aeruginosa hastane enfeksiyonları ile ilişkili önemli bir patojen olup patojenitesi çoğunlukla quorum

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... (QS) sistemi ile ilişkilidir. Bu çalışmanın amacı, vajinal Lactobacillus izolatlarının metabolitlerinin anti-QS aktivitelerinin değerlendirilmesi ve metabolitlerin P. aeruginosa PAO1'in QS ilişkili genlerinin transkripsiyonel regülasyonu üzerindeki etkilerinin araştırılmasıdır. Yöntem: Çalışmamızda daha önce 16S rRNA gen dizi analizi ile tanımlanmış olan 13 adet Lactobacillus izolatı kullanılmıştır. Bu izolatların metabolitlerinin, Chromobacterium violaceum CV12472 suşu kullanılarak anti-QS aktiviteleri değerlendirilmiştir. Metabolitlerin QS ile ilişkili genlerin ekspresyonları üzerindeki etkisi kantitatif revers transkriptaz polimeraz zincir reaksiyonu RT-qPZR ile araştırılmıştır. Bulgular: Test edilen tüm metabolitler C. violaceum'un şeffaf zon bölgesi görünümü ile karakterize edilen anti-QS aktivite göstermişlerdir. Metabolitlerle temas sonrasında P. aeruginosa PAO1'de, test edilen tüm quorum sensing ilişkili genler (lasI, lasR, rhlR ve mvfR) anlamlı bir down-regülasyon göstermişlerdir. ABSTRACT Objective: Pseudomonas aeruginosa is an important pathogen associated with nosocomial infections and its pathogenicity is mostly linked with the quorum sensing (QS) system. The aim of this study was to evaluate the anti-QS activity of the metabolites of vaginal Lactobacillus isolates and to investigate the effect of these metabolites on transcriptional regulation of QS related genes in P. aeruginosa PAO1. Methods: In this study, 13 Lactobacillus isolates that were previously identified by 16S rRNA gene sequence analysis were used. Metabolites of these isolates were assessed for the anti-QS activity by using Chromobacterium violaceum CV12472. The influence of metabolites on the expression of QS related genes was also examined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Results: All tested metabolites exhibited anti-QS activity with the appearance of a non-pigmented zone of C. violaceum. All tested quorum sensing-related genes (lasI, lasR, rhlR and mvfR) in P. aeruginosa PAO1 showed significant down-regulation after treating with the metabolites. of the anti-quorum sensing effect of Lactobacillus sp. metabolites on expression levels of QS-related genes in Pseudomonas aeruginosa PAO1. Turk Hij Den Biyol Derg, 2020; 77(3): 311-318 Makale Dili "İngilizce"/Article Language "English" Cilt 77  Sayı 3 2020 D. KART, S. S. GÜRPINAR and M. ERYILMAZ Shewanella baltica, the specific spoilage organism of the refrigerated shrimp. It was also concluded in the study that this antimicrobial effect was regulated by the AI-2 / LuxS-mediated QS system (27). CONCLUSION Many virulence genes may be overexpressed through the QS system in microorganisms following the transformation into more pathogenic forms. The discovery of new antimicrobial compounds targeting the QS system will result in inhibition of bacterial communication, thereby showing its activity without selective pressure on microorganisms. In our study, the metabolites of Lactobacillus vaginal isolates have been shown to have anti-QS activity. These natural compounds, alone or in combination with antibiotics, maybe future candidates for the treatment of P. aeruginosa biofilms in clinics.