Biological activity and chemical identification of ornithine lipid produced by Burkholderia gladioli pv. agaricicola ICMP 11096 using LC-MS and NMR analyses

Lipoamino acids (LAs) have been isolated from bacterial species and are included among the most important microbial secondary metabolites. Some synthetic LAs are being increasingly used in pharmaceutical applications such as ornithine lipid (OL) which is present in relatively large amounts in some G-ve bacteria. Many Burkholderia spp. produce in vitro secondary metabolites with lipodepsipeptide nature and have showed relevant biological activities and potential practical applications. The purposes of this research were i) to study the antibacterial activity of cell-free culture filtrate of B. gladioli pv. agaricicola strain ICMP 11096; ii) HPLC fractionation and antibacterial evaluation of isolated compounds; iii) Finally, the identification by LC-MS and NMR analysis of the principle bioactive compound produced by the bacterium. Results showed that the cell-free culture filtrate has a promising antibacterial activity against the two studied target microorganisms. In addition, HPLC fractionation demonstrated the presence of five single bioactive compounds produced by the bacterium and their antibacterial activity stated that peak no. 2 is the most bioactive one against B. megaterium and E. coli. Successively, the principal bioactive compound was identified by LC-MS and ¹H NMR as OL with mass spectrum (m/z) 719. This research is considered the first report of isolation and chemical identification of OL compound isolated from B. gladioli pv. agaricicola ICMP 11096.