title: Disruption of the 2-methylcitric acid cycle and evaluation of poly-3-hydroxybutyrate-co-3-hydroxyvalerate biosynthesis suggest alternate catabolic pathways of propionate in Burkholderia sacchari.
abstract: The objective of the present work was to evaluate the relevance of the 2-methylcitric acid cycle (2MCC) to the catabolism of propionate in Burkholderia sacchari. Two B. sacchari mutants unable to grow on propionate were obtained: one disrupted in acnM, and the other in acnM and prpC deleted. An operative 2MCC significantly reduces the bacterial ability to incorporate 3-hydroxyvalerate (3HV) into a biodegradable copolyester accumulated from carbohydrates plus propionate. The efficiency of the mutants in converting propionate to 3HV units (Y(3HV/prp)) increased from 0.09 g*g(-1) to 0.81-0.96 g*g(-1), indicating that acnM and prpC are both essential for growth on propionate. None of the mutations resulted in achievement of the maximum theoretical Y3HV/prp (1.35 g*g(-1)). When increasing concentrations of propionate were supplied, decreasing values of Y3HV/prp were observed. The results obtained corroborate the hypothesis of the presence of other propionate catabolic pathways in B. sacchari. The 2MCC would be the more operative pathway, but a second pathway, which remains to be elucidated, would assume more importance under propionate concentrations of 1 g*L(-1) or higher. The efficiency in converting propionate to 3HV units can be improved by decreasing the propionate concentrations, owing to the role of the 2MCC.
authors.affiliation: Departamento de Microbiologia, Instituto de Ciencias Biomédicas, Universidade de São Paulo, CEP 05508-000, São Paulo SP, Brazil.
authors.forename: Erica Mendes
authors.initials: EM
authors.lastname: Pereira
authors.forename: Sonia Regina
authors.initials: SR
authors.lastname: Silva-Queiroz
authors.forename: José Gregório
authors.initials: JG
authors.lastname: Cabrera Gomez
authors.forename: Luiziana Ferreira
authors.initials: LF
authors.lastname: Silva
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D053898:Biosynthetic Pathways; D019117:Burkholderia / Q000235:genetics / Q000378:metabolism*; D002951:Citrates / Q000378:metabolism*; D011091:Polyesters / Q000378:metabolism*; D011422:Propionates / Q000378:metabolism*; D017384:Sequence Deletion; D000094122:Polyhydroxybutyrates
chemical_list: D001426:Bacterial Proteins; D002951:Citrates; D011091:Polyesters; D011422:Propionates; C052620:poly(3-hydroxybutyrate)-co-(3-hydroxyvalerate); D000094122:Polyhydroxybutyrates; C031605:2-methylcitric acid