Polyhydroxyalkanoates: Much More than Biodegradable Plastics.
Bacterial polyhydroxyalkanoates (PHAs) are isotactic polymers that play a critical role in central metabolism, as they act as dynamic reservoirs of carbon and reducing equivalents. These polymers have a number of technical applications since they exhibit thermoplastic and elastomeric properties, making them attractive as a replacement of oil-derived materials. PHAs are accumulated under conditions of nutritional imbalance (usually an excess of carbon source with respect to a limiting nutrient, such as nitrogen or phosphorus). The cycle of PHA synthesis and degradation has been recognized as an important physiological feature when these biochemical pathways were originally described, yet its role in bacterial processes as diverse as global regulation and cell survival is just starting to be appreciated in full. In the present revision, the complex regulation of PHA synthesis and degradation at the transcriptional, translational, and metabolic levels are explored by analyzing examples in natural producer bacteria, such as Pseudomonas species, as well as in recombinant Escherichia coli strains. The ecological role of PHAs, together with the interrelations with other polymers and extracellular substances, is also discussed, along with their importance in cell survival, resistance to several types of environmental stress, and planktonic-versus-biofilm lifestyle. Finally, bioremediation and plant growth promotion are presented as examples of environmental applications in which PHA accumulation has successfully been exploited.
Departamento de Química Biológica and Instituto de Química Biológica (IQUIBICEN-CONICET), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
Nancy I
NI
López
Departamento de Química Biológica and Instituto de Química Biológica (IQUIBICEN-CONICET), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
M Julia
MJ
Pettinari
Systems and Synthetic Biology Program, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain.
Pablo I
PI
Nikel
Departamento de Química Biológica and Instituto de Química Biológica (IQUIBICEN-CONICET), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
Beatriz S
BS
Méndez
D063566:Biodegradable Plastics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D054813:Polyhydroxyalkanoates / Q000378:metabolism*; D016958:Pseudomonas putida / Q000235:genetics / Q000378:metabolism*
D063566:Biodegradable Plastics; D054813:Polyhydroxyalkanoates
Bacteria; Bacterial ecology; Central metabolism; Global regulation; Polyhydroxyalkanoates