Determination of diketopiperazines of Burkholderia cepacia CF-66 by gas chromatography–mass spectrometry

Abstract

Bacteria communicate with each other by a process termed "quorum sensing" (QS), and diffusible, low-molecular-weight chemicals, called signal molecules, are used as the communication languages. In cell-free Burkholderia cepacia CF-66 culture supernatants, five compounds suspected of being signal molecules were identified. The gene (cepI) related with AHLs synthesis were not detected by polymerase chain reaction (PCR) using specific primers. Gas chromatography-mass spectrometry (GC-MS) revealed that these compounds were not AHLs but the diketopiperazines (DKPs) cyclo(Pro-Phe), cyclo(Pro-Tyr), cyclo(Ala-Val), cyclo(Pro-Leu), and cyclo(Pro-Val), all of which were both D and L-type. Four kinds of DKPs had been isolated from other gram-negative bacteria, but the other was a novel kind discovered in CF-66, and L-cyclo (Pro-Phe) was quantified by GC-MS. It was found that exogenous DKPs had a negative effect on the candidacidal activity of the culture supernatant extracts.

Inhibition of biofilm in Bacillus amyloliquefaciens Q-426 by diketopiperazines

“…In previous study, B. amyloliquefaciens Q-426 was found to be a potential biocontrol agent against fungi and bacteria, but the biofilm formation played a negative role on it (Zhao et al 2013;Zhao et al 2014). In this study, the DKPs extracted from B. amyloliquefaciens Q-426, which was suspected as signal molecule of several bacterial (Degrassi et al 2002;Holden et al 1999;Wang et al 2010b), can inhibit the biofilm formation of the strain by inhibiting the extracellular polymeric matrix formation.…”

“…The extraction method of DKPs from the culture supernatants has been described previously (Wang et al 2010b). Briefly, supernatants (20 L) from stationary-phase cultures of sample bacteria were extracted with equal volume of acidified ethyl acetate (0.5 % acetic acid) three times.…”

“…A Bruker AVANCE III NMR Spectrometer (Bruker, Germany) of 500 MHz equipped with 13 C/ 1 H dual probe was deployed to measure the 1 H spectrum of the compounds. The mass spectra of the compounds were determined on a GCMS-QP2010 Plus (Shimadzu, Japan), and the detailed parameters set were described previously (Wang et al 2010b). …”

Endophytic Streptomyces in the traditional medicinal plant Arnica montana L.: secondary metabolites and biological activity

“…Cyclo-isoleucyl-prolyl and cyclo-prolyl-valyl were not present in the NIST11 database. Identification was done by comparison with published fragmentation patterns (Bitzer 2005;Wang et al 2010;Ortiz-Castro et al 2011). Only extract 3 contained all mentioned molecules and the respective strain was therefore chosen for genome sequencing.…”

Gas Chromathography as a Tool in Quorum Sensing Studies

“…The bacterial culture is centrifuged an the supernatant is extracted with common solvents such as ethyl acetate, chloroform and dichloromethane to obtain the signaling molecules such as AHLs, DKP and PQS (Pesci et al, 1999;Pomini et al, 2005;Wang et al, 2010). In order to prevent degradation of AHLs the extractive solvent contains acetic acid, formic acid or TFA acid in concentration from 0.05 to 1.0 % (v/v) (Götz et al, 2007;.…”