Characterization of Respiration in Paraburkholderia tropica Ppe8T under Static Culture Conditions

Abstract

Objective: To investigate the respiratory chain of Paraburkholderia tropica under limited oxygen conditions would allow us to better understand their functions in plant tissue. Methods: We first optimized the medium for P. tropica biomass production in static culture. Oxidase and Oxidoreductase activities were determined in absence and presence de inhibitors. Spectroscopic analysis of cytochromes was obtained at room and liquid nitrogen temperature. Findings: Isolated membranes showed respiratory oxidase activities with succinate, glucose, NADH and ascorbate-N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD). Succinate and glucose respiration were inhibited by 2-heptyl-4-hydroxyquinoline-N-oxide, antimycin A and myxothiazol, suggesting the presence of a bc> 1 complex. KCN inhibition curves in the presence of ascorbate-TMPD, succinate or glucose were biphasic, with KCN-sensitive and -resistant oxidases. Spectral analysis with physiological or artificial substrates revealed the presence of only cytochromes b and c , with remarkable cytochrome reduction by ascorbate alone. The CO difference and photodissociation spectra of glucose-reduced membranes revealed one component with the spectral features of a cytochrome o´ -like CO complex. Air-oxidation spectra of the cytochromes with KCN showed that cytochrome c is an obligate participant in the KCN-sensitive pathway and revealed the presence of a cyanide-resistant oxidase cytochrome bo . Novelty: The characterization of the electron transport system of P. tropica allowed us to propose the following components: 1. Dehydrogenases for succinate, glucose and NADH, 2. A ubiquinone, 3. A bc complex and 4. Two oxidases, cbb -type cytochrome c oxidase and bo -type quinol oxidase.