TY - JOUR
T1 - In situ identification of plant-invasive bacteria with MALDI-TOF mass spectrometry
AU - Ziegler, Dominik
AU - Mariotti, Anna
AU - Pflüger, Valentin
AU - Saad, Maged
AU - Vogel, Guido
AU - Tonolla, Mauro
AU - Perret, Xavier
N1 - Funding Information:
Co-authors Valentin Pflüger and Guido Vogel are employees of Marbitrec AG. Dominik Ziegler is a PhD student in Geneva whose research is partially funded by Mabritec AG. There are no patents or products in development to declare. This does not alter the authors' adherence to all of the PLoS ONE policies on sharing data and materials.
PY - 2012/5/17
Y1 - 2012/5/17
N2 - Rhizobia form a disparate collection of soil bacteria capable of reducing atmospheric nitrogen in symbiosis with legumes. The study of rhizobial populations in nature involves the collection of large numbers of nodules found on roots or stems of legumes, and the subsequent typing of nodule bacteria. To avoid the time-consuming steps of isolating and cultivating nodule bacteria prior to genotyping, a protocol of strain identification based on the comparison of MALDI-TOF MS spectra was established. In this procedure, plant nodules were considered as natural bioreactors that amplify clonal populations of nitrogen-fixing bacteroids. Following a simple isolation procedure, bacteroids were fingerprinted by analysing biomarker cellular proteins of 3 to 13 kDa using Matrix Assisted Laser Desorption/Ionization Time of Flight (MALDI-TOF) mass spectrometry. In total, bacteroids of more than 1,200 nodules collected from roots of three legumes of the Phaseoleae tribe (cowpea, soybean or siratro) were examined. Plants were inoculated with pure cultures of a slow-growing Bradyrhizobium japonicum strain G49, or either of two closely related and fast-growing Sinorhizobium fredii strains NGR234 and USDA257, or with mixed inoculants. In the fully automatic mode, correct identification of bacteroids was obtained for >97% of the nodules, and reached 100% with a minimal manual input in processing of spectra. These results showed that MALDI-TOF MS is a powerful tool for the identification of intracellular bacteria taken directly from plant tissues.
AB - Rhizobia form a disparate collection of soil bacteria capable of reducing atmospheric nitrogen in symbiosis with legumes. The study of rhizobial populations in nature involves the collection of large numbers of nodules found on roots or stems of legumes, and the subsequent typing of nodule bacteria. To avoid the time-consuming steps of isolating and cultivating nodule bacteria prior to genotyping, a protocol of strain identification based on the comparison of MALDI-TOF MS spectra was established. In this procedure, plant nodules were considered as natural bioreactors that amplify clonal populations of nitrogen-fixing bacteroids. Following a simple isolation procedure, bacteroids were fingerprinted by analysing biomarker cellular proteins of 3 to 13 kDa using Matrix Assisted Laser Desorption/Ionization Time of Flight (MALDI-TOF) mass spectrometry. In total, bacteroids of more than 1,200 nodules collected from roots of three legumes of the Phaseoleae tribe (cowpea, soybean or siratro) were examined. Plants were inoculated with pure cultures of a slow-growing Bradyrhizobium japonicum strain G49, or either of two closely related and fast-growing Sinorhizobium fredii strains NGR234 and USDA257, or with mixed inoculants. In the fully automatic mode, correct identification of bacteroids was obtained for >97% of the nodules, and reached 100% with a minimal manual input in processing of spectra. These results showed that MALDI-TOF MS is a powerful tool for the identification of intracellular bacteria taken directly from plant tissues.
UR - http://www.scopus.com/inward/record.url?scp=84861204948&partnerID=8YFLogxK
U2 - 10.1371/journal.pone.0037189
DO - 10.1371/journal.pone.0037189
M3 - Article
C2 - 22615938
AN - SCOPUS:84861204948
SN - 1932-6203
VL - 7
JO - PloS one
JF - PloS one
IS - 5
M1 - e37189
ER -