Induction by Bradyrhizobium diazoefficiens of different catabolic pathways for growth in D-mannitol or L-arabinose leading to pronounced differences in CO2 fixation, O2 consumption, and lateral-flagellum production
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ABSTRACT: Bradyrhizobium diazoefficiens, the soybean N2-fixing symbiont, uses mannitol or arabinose as carbon and energy source, among other substances. In this bacterium, growth with mannitol led to higher biomass production, and inhibited the synthesis of its secondary (lateral) flagellar system, regarding growth with arabinose. A proteomic comparison of bacteria grown in mannitol or arabinose suggested that mannitol may be degraded by the Calvin-Benson-Bassham pathway, while arabinose seems degraded by the L-2-keto-3-deoxyarabonate pathway, both pathways sharing only the reactions from pyruvate to CO2. Despite these differences, the stoichiometric balances resulted in similar O2 consumption and ATP production per C-mole of substrate. The poly-3-hydroxybutyrate biosynthesis pathway was stimulated in mannitol, while in arabinose there was a consistent increase in enzymes for the synthesis of nicotinamide adenine dinucleotide from aspartate, suggesting a surplus of reducing power in mannitol. This may agree to previous reports showing higher O2 consumption rate in arabinose, which taking into account the similarity in O2 consumption balance, suggests higher maintenance energy demand in this carbon and energy source. Since lateral flagella are produced only in arabinose, we wondered whether their energy demand might explain this difference. Hence, we compared the O2 consumption rates in mannitol and arabinose of the wild-type and a lafR::Km mutant devoid of lateral flagella. We observed that, while there was a three-fold higher O2 consumption rate in the wild-type in arabinose with respect to mannitol, there was no difference in the mutant, suggesting that lateral flagella behave as parasitic structures in this medium.
INSTRUMENT(S): Q Exactive
ORGANISM(S): Bradyrhizobium Japonicum Usda 110
TISSUE(S): Prokaryotic Cell
DISEASE(S): Disease Free
SUBMITTER: Carolina Cogo
LAB HEAD: Anibal Roberto Lodeiro
PROVIDER: PXD008263 | Pride | 2018-06-25
REPOSITORIES: Pride
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