Characterization by Tandem Mass Spectrometry of Biologically Active Compounds Produced by Bacillus Strains

Among Gram-positive bacteria, Bacillus strains are known to produce numerous compounds that display a large spectrum of biological activities [1]. Owing to their production of antimicrobial substances, Bacillus strains can act as biological control agents for plant diseases [2] and some of these substances have an effect on plant pathogens [3]. Furthermore, these bacteria have beneficial effects on human health that are directly connected to their production of anti-microbial substances [4] and probiotics based on Bacillus bacteria contribute to the prevention and treatment of infectious diseases [5] and gastrointestinal microbial disorders [6]. Many compounds produced by Bacillus strains are characterized by an alkyl chain of variable length linked to a cyclic peptide, and thus can be classified as lipopeptides. Their amino acid composition and fatty acid chain length are variable, as well as the type of ring closure, thus leading to the occurrence of numerous isoforms and isobaric species (Figure 1). Surfactins are powerful biosurfactants with exceptional emulsifying and foaming properties [7]. This family encompasses structural variants, but all members are heptapeptides interlinked with a β-hydroxy fatty acid to form a cyclic lactone ring structure. Fengycins, which are also called plipastatins, are lipodecapeptides with an internal lactone ring in the peptidic moiety linked to a β-hydroxy fatty acid chain that can be saturated or unsaturated. Fengycins are less hemolytic than surfactins but retain a strong fungitoxic activity [7]. Other compounds synthesized by Bacillus strains were listed as antibiotic compounds. In 1974, Berdy reported 167 antibiotics produced by members of the Bacillus genus [8]. Since then, many new antibiotics have been isolated from strains of the Bacillus genus and have found applications in the pharmacology, veterinary and food industries [9]. These compounds include low molecular weight species (below 500 Da) such as amicoumacins JOURNAL OF APPLIED BIOANALYSIS, Jan. 2015, p. 19-25. http://dx.doi.org/10.17145/jab.15.004 Vol. 1, No. 1