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Infections by Burkholderia cenocepacia lead to life-threatening disease in immunocompromised individuals, including those living with cystic fibrosis (CF). While genetic variation in various B. cenocepacia strains has been reported, it remains unclear how the chemical environment of CF lung influences the production of small molecule virulence factors by these strains. Here we compare metabolomes of three clinical B. cenocepacia strains in synthetic CF sputum medium (SCFM2) and in a routine laboratory medium (LB), in the presence and absence of the antibiotic trimethoprim. Using a mass spectrometry-based untargeted metabolomics approach, we identify several compound classes which are differentially produced in SCFM2 compared to LB media, including siderophores, antimicrobials, quorum sensing signals, and various lipids. Furthermore, we describe that specific metabolites are induced in the presence of the antibiotic trimethoprim only in SCFM2 when compared to LB. Herein, C13-acyl-homoserine lactone, a quorum sensing signal previously not known to be produced by B. cenocepacia as well as pyochelin-type siderophores were exclusively detected during growth in SCFM2 in the presence of trimethoprim. The comparative metabolomics approach described in this study provides insight into environment-dependent production of secondary metabolites by B. cenocepacia strains and suggests future work which could identify personalized strain-specific regulatory mechanisms involved in production of secondary metabolites. Investigations into whether antibiotics with different mechanisms of action induce similar metabolic alterations will inform development of combination treatments aimed at effective clearance of Burkholderia spp. pathogens.

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Methods have been developed for the determination of sulphur, sulphide, thiosulphate, sulphite and sulphate when present together in commercial calcium chloride. The analysis is divided into three sections: Section I.—Precipitation of sulphide by addition of zinc carbonate suspension; the precipitate also contains all the elementary sulphur present in the sample, and some insoluble sulphite and sulphate. The filtrate contains soluble thiosulphate, sulphite and sulphate, and these are determined by well‐known methods. The zinc carbonate precipitate is examined for sulphide and insoluble sulphite by iodine titration. The precipitate from another zinc carbonate separation is added to an excess of acidified iodine solution in which case sulphur is precipitated in amount equivalent to the sulphide present. This sulphur is separated together with any sulphur present in the sample, oxidized to sulphate and determined as barium sulphate. The filtrate from the acidified iodine separation of sulphur contains sulphate equivalent to the insoluble sulphate and sulphite associated with the zinc carbonate separation. Section 2.—Total sulphate is determined in the sample by first boiling with dilute hydrochloric acid and then precipitating the sulphate with barium chloride. Section 3.—A third portion of the sample is used for the determination of insoluble sulphite plus total sulphide. A separation of the insoluble sulphite and sulphide is carried out with zinc carbonate suspension and the mixture filtered. The sulphide together with insoluble sulphite is determined in the precipitate by titration with iodine. The filtrate contains soluble sulphate, sulphite and thiosulphate. From the results of analyses of each section and by a series of calculations the contents of sulphur, sulphide, thiosulphate, sulphite and sulphate can be obtained. The scheme of analysis is shown on p. 367.