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The turnover of medium-chain-length polyhydroxyalkanoates in Pseudomonas putida KT2442 and the fundamental role of PhaZ depolymerase for the metabolic balance.
- Source :
-
Environmental microbiology [Environ Microbiol] 2010 Jan; Vol. 12 (1), pp. 207-21. Date of Electronic Publication: 2009 Sep 29. - Publication Year :
- 2010
-
Abstract
- Polyhydroxyalkanoates (PHAs) are biodegradable polymers produced by a wide range of bacteria, including Pseudomonads. These polymers are accumulated in the cytoplasm as carbon and energy storage materials when culture conditions are unbalanced and hence, they have been classically considered to act as sinks for carbon and reducing equivalents when nutrients are limited. Bacteria facing carbon excess and nutrient limitation store the extra carbon as PHAs through the PHA polymerase (PhaC). Thereafter, under starvation conditions, PHA depolymerase (PhaZ) degrades PHA and releases R-hydroxyalkanoic acids, which can be used as carbon and energy sources. To study the influence of a deficient PHA metabolism in the growth of Pseudomonas putida KT2442 we have constructed two mutant strains defective in PHA polymerase (phaC1)- and PHA depolymerase (phaZ)-coding genes respectively. By using these mutants we have demonstrated that PHAs play a fundamental role in balancing the stored carbon/biomass/number of cells as function of carbon availability, suggesting that PHA metabolism allows P. putida to adapt the carbon flux of hydroxyacyl-CoAs to cellular demand. Furthermore, we have established that the coordination of PHA synthesis and mobilization pathways configures a functional PHA turnover cycle in P. putida KT2442. Finally, a new strain able to secrete enantiomerically pure R-hydroxyalkanoic acids to the culture medium during cell growth has been engineering by redirecting the PHA cycle to biopolymer hydrolysis.
- Subjects :
- Acyltransferases genetics
Acyltransferases metabolism
Bacterial Proteins genetics
Carbon metabolism
Carboxylic Ester Hydrolases genetics
Gene Deletion
Gene Expression Regulation, Bacterial
Microbial Viability
Nitrogen metabolism
Pseudomonas putida genetics
Pseudomonas putida growth & development
Substrate Specificity
Bacterial Proteins metabolism
Carboxylic Ester Hydrolases metabolism
Polyhydroxyalkanoates metabolism
Pseudomonas putida metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1462-2920
- Volume :
- 12
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Environmental microbiology
- Publication Type :
- Academic Journal
- Accession number :
- 19788655
- Full Text :
- https://doi.org/10.1111/j.1462-2920.2009.02061.x