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J Biotechnol. 2018 Mar 20;270:30-38. doi: 10.1016/j.jbiotec.2018.01.023. Epub 2018 Feb 3.

Soil metagenome-derived 3-hydroxypalmitic acid methyl ester hydrolases suppress extracellular polysaccharide production in Ralstonia solanacearum.

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Department of Applied Bioscience, Dong-A University, Busan 49315, Republic of Korea.
Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Wuhan University, Wuhan, 430072, China.
Department of Chemistry, Dong-A University, Busan 49315, Republic of Korea.
Department of Applied Bioscience, Dong-A University, Busan 49315, Republic of Korea. Electronic address:


Autoinducers are indispensable for bacterial cell-cell communication. However, due to the reliance on culture-based techniques, few autoinducer-hydrolyzing enzymes are known. In this study, we characterized soil metagenome-derived unique enzymes capable of hydrolyzing 3-hydroxypalmitic acid methyl ester (3-OH PAME), an autoinducer of the plant pathogenic bacterium Ralstonia solanacearum. Among 146 candidate lipolytic clones from a soil metagenome library, 4 unique enzymes capable of hydrolyzing the autoinducer 3-OH PAME, termed ELP86, ELP96, ELP104, and EstDL33, were selected and characterized. Phylogenetic analysis revealed that metagenomic enzymes were novel esterase/lipase candidates as they clustered as novel subfamilies of family I, V, X, and family XI. The purified enzymes displayed various levels of hydrolytic activities towards 3-OH PAME with optimum activity at 40-50 °C and pH 7-10. Interestingly, ELP104 also displayed N-(3-oxohexanoyl)-L-homoserine lactone hydrolysis activity. Heterologous expression of the gene encoding 3-OH PAME hydrolase in R. solanacearum significantly decreased exopolysaccharide production without affecting bacterial growth. mRNA transcription analysis revealed that genes regulated by quorum-sensing, such as phcA and xpsR, were significantly down-regulated in the stationary growth phase of R. solanacearum. Therefore, metagenomic enzymes are capable of quorum-quenching by hydrolyzing the autoinducer 3-OH PAME, which could be used as a biocontrol strategy against bacterial wilt.


3-Hydroxy palmitic acid methyl ester hydrolases; Quorum quenching; Ralstonia solanacearum; Soil metagenome

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