| Autor: |
Retamal-Morales G; Biology Department, Universidad de Santiago de Chile, Av. Libertador Bernardo O'Higgins, 3363, Santiago, Chile.; Institute of Biosciences, TU Bergakademie Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany., Senges CHR; Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstr. 150, 44780, Bochum, Germany., Stapf M; Institute of Organic Chemistry, TU Bergakademie Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany., Olguín A; Environmental Sciences Department, Universidad de Santiago de Chile, Av. Libertador Bernardo O'Higgins, 3363, Santiago, Chile., Modak B; Environmental Sciences Department, Universidad de Santiago de Chile, Av. Libertador Bernardo O'Higgins, 3363, Santiago, Chile., Bandow JE; Applied Microbiology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstr. 150, 44780, Bochum, Germany., Tischler D; Institute of Biosciences, TU Bergakademie Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany.; Microbial Biotechnology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstr. 150, 44780, Bochum, Germany., Schlömann M; Institute of Biosciences, TU Bergakademie Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany. michael.schloemann@ioez.tu-freiberg.de., Levicán G; Biology Department, Universidad de Santiago de Chile, Av. Libertador Bernardo O'Higgins, 3363, Santiago, Chile. gloria.levican@usach.cl. |
| Abstrakt: |
Rhodococcus erythropolis S43 is an arsenic-tolerant actinobacterium isolated from an arsenic contaminated soil. It has been shown to produce siderophores when exposed to iron-depleting conditions. In this work, strain S43 was shown to have the putative heterobactin production cluster htbABCDEFGHIJ(K). To induce siderophore production, the strain was cultured in iron-depleted medium in presence and absence of sodium arsenite. The metabolites produced by S43 in the colorimetric CAS and As- m CAS assays, respectively, showed iron- and arsenic-binding properties reaching a chelating activity equivalent to 1.6 mM of desferroxamine B in the supernatant of the culture without arsenite. By solid-phase extraction and two subsequent HPLC separations from both cultures, several fractions were obtained, which contained CAS and As- m CAS activity and which were submitted to LC-MS analyses including fragmentation of the major peaks. The mixed-type siderophore heterobactin B occurred in all analyzed fractions, and the mass of the "Carrano heterobactin A" was detected as well. In addition, generation of a molecular network based on fragment spectra revealed the occurrence of several other compounds with heterobactin-like structures, among them a heterobactin B variant with an additional CH 2 O moiety. 1 H NMR analyses obtained for preparations from the first HPLC step showed signals of heterobactin B and of "Carrano heterobactin A" with different relative amounts in all three samples. In summary, our results reveal that in R. erythropolis S43, a pool of heterobactin variants is responsible for the iron- and arsenic-binding activities. KEY POINTS: • Several heterobactin variants are the arsenic-binding compounds in Rhodococcus erythropolis S43. • Heterobactin B and the compound designated heterobactin A by Carrano are of importance. • In addition, other heterobactins with ornithine in the backbone exist, e.g., the new heterobactin C. |
