Surang ChankhamhaengdechaSuphatra HongvijitAkkaraphol SrichaisupakitPattra CharnchaiWatanalai PanbangredMahidol UniversityCenter of Excellence on Agricultural Biotechnology: (AG-BIO/PERDO-CHE)2018-10-192018-10-192013-03-11BioMed Research International. Vol.2013, (2013)23146141231461332-s2.0-84874624549https://repository.li.mahidol.ac.th/handle/20.500.14594/31347Several Gram-negative pathogenic bacteria employ N-acyl-L-homoserine lactone (HSL) quorum sensing (QS) system to control their virulence traits. Degradation of acyl-HSL signal molecules by quorum quenching enzyme (QQE) results in a loss of pathogenicity in QS-dependent organisms. The QQE activity of actinomycetes in rhizospheric soil and inside plant tissue was explored in order to obtain novel strains with high HSL-degrading activity. Among 344 rhizospheric and 132 endophytic isolates, 127 (36.9%) and 68 (51.5%) of them, respectively, possessed the QQE activity. The highest HSL-degrading activity was at 151.30 ± 3.1 nmole/h/mL from an endophytic actinomycetes isolate, LPC029. The isolate was identified as Streptomyces based on 16S rRNA gene sequence similarity. The QQE from LPC029 revealed HSL-acylase activity that was able to cleave an amide bond of acyl-side chain in HSL substrate as determined by HPLC. LPC029 HSL-acylase showed broad substrate specificity from C to CHSL in which CSL is the most favorable substrate for this enzyme. In an in vitro pathogenicity assay, the partially purified HSL-acylase efficiently suppressed soft rot of potato caused by Pectobacterium carotovorum ssp. carotovorum as demonstrated. To our knowledge, this is the first report of HSL-acylase activity derived from an endophytic Streptomyces. © 2013 Surang Chankhamhaengdecha et al.Mahidol UniversityBiochemistry, Genetics and Molecular BiologyImmunology and MicrobiologyMedicineArticleSCOPUS10.1155/2013/782847