RESEARCH ARTICLE

ll lo a (IAA) [2] and volatile compounds [3]. It is also known for antimicrobial proteins. P. polymyxa can produce several Niu et al. BMC Microbiology 2013, 13:137 http://www.biomedcentral.com/1471-2180/13/137nonribosomal peptide synthetase (NRPS) mechanism [31].10115, GermanyFull list of author information is available at the end of the articlecontrolling plant-parasitic nematodes [4,5] and fungal phytopathogens including Fusarium oxysporum [6], Fusar-ium graminearum [7], Aspergillus niger [8], Penicillium expansum [9], Leptosphaeria maculans [10], Phytophthora palmivora and Pythium aphanidermatum [11]. P. polymyxa has been recently used to control bacterial phytopathogens kinds of peptide antibiotics, including polymyxins [14-22], gavaserin and saltavidin [23], jolipeptin [24], gatavalin [25] and fusaricidins [26,27]. Polymyxins which are known for their strong inhibiting effects against gram-negative bacteria have been used to treat multidrug-resistant gram-negative bacteria [28] and to prevent septic shock [29]. The molecular structure of poly-myxin is comprised of a cyclic peptide chain and a hydro-phobic tail. Each member of polymyxins differs in the structures of fatty acids and the variations in the amino acid residues [30]. Polymyxins are synthesized by th