## 2 Results
Surface extracts were obtained by extraction of cell material with 50% acetonitrile/0.1% trifluoroacetic acid. \(m/z=899.6\) and 913.6 were found. They are related to fusaricidins A and B with a mass difference of 16 Da, indicating a hydroxylation of these species. In addition, for these new fusaricidins +71-derivatives (\(m/z=970.5\) and 984.5) appeared. All these variants were either not found or are present in only low amount in samples of the reference strain M1. The structure of all these new fusaricidins were investigated by fragment analysis using LIFT-MALDI-TOF/TOF mass spectrometry [56]. Fragment spectra for fusaricidin A (\(m/z=883.5\)) (A) and related compounds (\(m/z=954.6\) (B) and 899.6 (C)) are shown in Figure 3A-C.  
Figure 2: (**A**) MALDI-TOF mass spectrum of the culture filtrate of _P. polypmxa_ DSM 32871 cultivated in the LOP medium for 48 h in the mass range of \(m/z=800\)–1040 covering the fusaricidin complex. (**B**) HPLC-chromatopram demonstrating fractionation of the culture filtrate of DSM 32871. The ordinate shows scales for the absorption at 210 nm in mAU and for the percentage of the eluent acetonitrile. The abscissa indicates the fraction number and the elution time. In previous studies [10; 11] we demonstrated that by laser excitation fusaricidins preferentially are decomposed in \(\beta\)-position to the carboxyl group of their fatty acid residue forming two characteristic _fragments a and b_ according to the fragment pattern displayed in Scheme 1 for ring-opened fusaricidin A:  
_Fragment a_ functions as an indicator for the fatty acid constituent of fusaricidins which is shortened by the two carbon atoms at its C-terminal end, which are connected via the carboxyl group of the fatty acid component with the amino group of the starter amino acid being part of _fragment b_ containing the complete peptide chain. In Figure 3 the mass peak of _fragment a_ was strongly dominating in the product ion spectra of fusaricidins, while _fragment b_ appeared with substantially lower intensity. _Fragment b_ was visualized in the expanded mass region from \(m/z\) = 600-720. The molecular masses for the fusaricidins  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Fusaricidins \(m/z\)** & _m/z + 71_ & _Fragment a mlz_ & _Fragment b mlz_ & **HPLC-Fraction** \\ \hline  & 855.51 & & 256.10 (C15) & 600.16 & 24 \\  & & 228.09 (C13) & 628.18 & & \\  & & 926.55 & 256.0 & 671.42 & 24 \\  & 869.53 & & 25  
produced by _P. polymyxa_ DSM 32871 together with the mass data for the corresponding _fragment ions a and b_ derived from the product ion spectra are summarized in Table 1.  
In Figure 3A,B the fragment spectrum of fusaricidin A with a C15-guanidino-pentadeca-3-hydroxy fatty acid chain is shown. As is apparent from Scheme 1 [11] here the mass numbers of _fragments a and b_ amount to \(m/z\) = 256.3 and 628.3, respectively. For the +71-derivative the same value for _fragment a_ was found as for the unsubstituted fusaricidin A (Figure 3C), but _fragment b_ as apparent in Figure 3D was 71 mass units higher (\(m/z\) = 699.2) indicating that the modification is located in the peptide portion. In contrast, for the +16-variant of fusaricidin A (\(m/z\) = 899.6) _fragment a m/z_ = 272.2 (Figure 3E) was 16 mass units higher than for the unsubstituted fusaricidin A, while the peptide part (\(m/z\) = 628.3 for _fragment b_) remained unchanged (Figure 3F). Apparently, here the fatty acid part of the derivative is hydroxylated. By evaluation of the LIFT-TOF/TOF product ion spectra of the fusaricidins produced by DSM 32871 listed in Table 1, a third group of yet unknown variants was found with molecular masses \(m/z\) = 897.3 and 911.2, which revealed as derivatives of fusaricidins A and B, exhibiting a value of \(m/z\) = 270.3 for _fragment a_.