Degradation of N-Acylhomoserine Lactone Quorum Sensing Signaling Molecules by Potato Root Surface-Associated Chryseobacterium Strains

Abstract

N-Acylhomoserine lactones (AHLs) are used as quorum-sensing signaling molecules by many Gram-negative bacteria. Here, 413 bacterial strains were obtained from the roots of potato plants and screened for AHL-degrading bacteria using Chromobacterium violaceum reporter strains. Sixty one isolates degraded N-hexanoyl-L-homoserine lactone (C6-HSL) within 24 h. Based on their 16S rRNA gene sequences, most of these isolates were assigned to the genus Chryseobacterium and divided into eight groups. Most of the strains degraded N-decanoyl-L-homoserine lactone (C10-HSL) and were active against 3-oxo-substituted AHLs. Groups V and VI were more effective at inactivating AHLs. One group V strain, StRB402, showed putative AHL-lactonase activity. This is the first report of AHLdegrading Chryseobacterium strains.

AidC, a Novel N -Acylhomoserine Lactonase from the Potato Root-Associated Cytophaga-Flavobacteria-Bacteroides (CFB) Group Bacterium Chryseobacterium sp. Strain StRB126

“…2B). In our previous study, putative AHL lactonase activities were detected from StRB126 (16). Therefore, to determine whether AidC functions as an AHL lactonase, the structure of C 10 -HSL treated with MBP-AidC was analyzed by HPLC.…”

“…In a previous study, we isolated 34 AHL-degrading Chryseobacterium strains from the roots of potato plants and divided them into eight related species groups (16). We now attempted to amplify by PCR procedures the aidC-homologous genes from the three AHL-degrading Chryseobacterium strains which belong to group VI, as well as StRB126 (16). The group VI strains, which were StLB126, StLB340, StLB341, and StLB342, had higher AHL-degrading activity than the other groups (16).…”

“…We now attempted to amplify by PCR procedures the aidC-homologous genes from the three AHL-degrading Chryseobacterium strains which belong to group VI, as well as StRB126 (16). The group VI strains, which were StLB126, StLB340, StLB341, and StLB342, had higher AHL-degrading activity than the other groups (16). Specific primers were designed FIG 7 (A) Optimal pH of AHL-degrading activity of purified MBP-AidC.…”

“…ACKQ00000000). However, we have previously reported that C. gleum NBRC 15054 did not show any AHLdegrading activity (16). To assess whether the AidC homolog (aidC 15054 ) from NBRC 15054 shows AHL lactonase activity, aidC 15054 was amplified from the chromosome of NBRC 15054 and cloned into the pUC118 cloning vector.…”

“…In previous studies, we have reported the putative AHL lactonase activities in the potato root-associated strains of Chryseobacterium sp., which is a member of the Cytophaga-FlavobacteriumBacteroides (CFB) group (16). Recently, it was reported that the fish pathogen Tenacibaculum maritimum, also a member of the CFB group, produces and degrades AHLs (18).…”