GC-MS Volatolomic Approach to Study the Antimicrobial Activity of the Antarctic Bacterium Pseudoalteromonas sp. TB41

Many bacteria produce a wide range of volatile info-chemicals compounds (mVOCs) that constitute an important regulatory factor in the interrelationships among different organisms in microbial ecosystems. It has been shown that Antarctic bacteria isolated from three different sponge species, by producing mVOCs, are able to inhibit specifically the growth of Burkholderia cepacia complex (Bcc) strains (i.e. opportunistic pathogens of cystic fibrosis patients) as demonstrated by cross-streaking inhibition assays. This study reports a metabolomics approach to investigate the volatile profile of both the Antarctic sponge associated Pseudoalteromonas sp. TB41 (P-sp-TB41) and Burkholderia cenocepacia strain LMG16654 (Bc-LMG16654) under aerobic conditions. Solid phase micro extraction (SPME) in head space of biological samples allowed an in vivo sampling of mVOCs with minimal specimen disturbance. The SPME fiber was termically desorbed in the injection port of gas chromatography–mass spectrometer (GC–MS) system setted in EI scan mode. The raw data were processed using both an automated mass spectra deconvolution and identification system and a metabolomic approach, which allowed a selection of 30 compounds presumably responsible for the inhibition of Bc-LMG16654 growth. The results obtained from samples prepared under cross-streaking conditions also suggest that the presence of Bc-LMG16654 cells neither interferes with the production of mVOCs nor induces the synthesis of different mVOCs. The employing of mass spectrometry played a key role in tuning the experimental system and in the evaluation of results. The use of this approach to study the interaction, in aerobic condition, among other Antarctic bacteria and Bcc and the possibility to extend this approach to other pathogenantagonist relationship, is currently in progress.