Characterization of N-acyl homoserine lactone overproducing mutants of Burkholderia multivorans ATCC 17616

Abstract

Burkholderia multivorans ATCC 17616 ordinarily produces insufficient amounts of N-acyl homoserine lactones (AHLs) to promote AHLdependent formation of the pigment violacein by the reporter strain Chromobacterium violaceum CV026. We have isolated AHLoverproducing mutants of strain 17616 by screening for variants which do cross-feed AHLs to strain CV026. Nucleotide-sequence analysis of the bmuIR locus which specifies AHL synthase (BmuI) and AHL-binding transcriptional activator protein (BmuR) indicated that the increased capacity to produce AHLs was not a consequence of changes upstream or internal to the bmuI or bmuR genes. We conclude that the mutations leading to AHL overproduction lie outside the bmuI/bmuR locus. ß

Biofilm Formation and Acyl Homoserine Lactone Production in the Burkholderia cepacia Complex

“…We do not yet understand the significance of the increase in biofilm formation for genomovar III-A strains over that for genomovar III-B strains, but it would be informative to study a larger number of strains from these two subgenomovar groups to determine if this relationship is true for a larger population. The results of our survey of acyl-HSLs synthesized by BCC isolates was in agreement with previous reports that most of these organisms synthesize C 8 -HSL (10,19,36). Exceptions included a genomovar III isolate that produced C 4 -HSL and/or 3OC 6 -HSL and two genomovar V isolates that synthesized C 10 -HSL in greatest abundance.…”

“…C4455 synthesized an unidentified species that eluted in fraction 32 under the HPLC conditions used. This species eluted between C 6 -HSL and C 8 -HSL and may resemble a previously reported unidentified species that migrates between C 6 -HSL and C 8 -HSL on C 18 reversed-phase thin layer chromatography plates (19,36). One organism, ATCC 17765 (genomovar III-B), produced C 4 -HSL and/or 3OC 6 -HSL, which elute together under the HPLC conditions used.…”

“…Under the HPLC conditions used, this molecule eluted between C 6 -HSL and C 8 -HSL. Other investigators have also reported unidentified molecules that eluted between C 6 -HSL and C 8 -HSL for both a genomovar II and genomovar VII isolate (19,36). It remains to be determined if these species are acyl-HSLs.…”

“…In all cases, except for the genomovar II isolates, at least one autoinducer synthase gene was identified, indicating that these organisms have the genetic potential for acyl-HSL synthesis. Recently it was reported that one genomovar II organism, B. multivorans ATCC 17616, readily gave rise to mutants that produced high levels of acyl-HSL and that it contained a novel acyl-HSL synthase gene, bmuI (36). It is likely that other genomovar II strains contain bmuI and that most BCC organisms have the ability to synthesize acyl-HSLs.…”

A Quorum-Quenching Approach To Investigate the Conservation of Quorum-Sensing-Regulated Functions within the Burkholderia cepacia Complex

“…CepR controls the tight expression of cepI through binding to a lux box-like sequence that partially overlaps the Ϫ35 region of the putative cepI promoter (32,51), creating a classic autoinduction loop. QS systems that are highly homologous to the CepI/CepR system of B. cenocepacia were subsequently identified in all B. cepacia complex species investigated thus far (1,21,34,54). Several strains of B. vietnamiensis also produce N-decanoylhomoserine lactone (C10-HSL) in addition to C8-and C6-HSL via a second QS system that consists of BviI and BviR (9,21,34).…”