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.
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.
Pereira
Erica Mendes
EM
Departamento de Microbiologia, Instituto de Ciencias Biomédicas, Universidade de São Paulo, CEP 05508-000, São Paulo SP, Brazil.
Silva-Queiroz
Sonia Regina
SR
Cabrera Gomez
José Gregório
JG
Silva
Luiziana Ferreira
LF
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
D001426:Bacterial Proteins; D002951:Citrates; D011091:Polyesters; D011422:Propionates; C052620:poly(3-hydroxybutyrate)-co-(3-hydroxyvalerate); D000094122:Polyhydroxybutyrates; C031605:2-methylcitric acid