The protective role of PHB and its degradation products against stress situations in bacteria

• Published in: FEMS microbiology reviews 2021-05, Vol.45 (3), p.1
• Main Authors: Müller-Santos, Marcelo, Koskimäki, Janne J, Alves, Luis Paulo Silveira, de Souza, Emanuel Maltempi, Jendrossek, Dieter, Pirttilä, Anna Maria
• Format: Article
• Language: English
• Subjects: Aldehydes - chemistry; Aldehydes - metabolism; Archaea; Availability; Bacteria; Bacteria - metabolism; Biodegradation; Biopolymers; Carbon; Carbon sequestration; Carbon sources; Cellular stress response; Degradation products; Drug resistance in microorganisms; Environmental monitoring; Heat shock; Nutrient availability; Oligomers; Oxidative stress; Physiological aspects; Polyhydroxyalkanoates; Polyhydroxybutyrate; Polyhydroxybutyric acid; Protein interaction; Reactive oxygen species; Stress, Physiological - physiology
• ISSN: 1574-6976; 0168-6445; 1574-6976
• DOI: 10.1093/femsre/fuaa058

ABSTRACT Many bacteria produce storage biopolymers that are mobilized under conditions of metabolic adaptation, for example, low nutrient availability and cellular stress. Polyhydroxyalkanoates are often found as carbon storage in Bacteria or Archaea, and of these polyhydroxybutyrate (PHB) is the most frequently occurring PHA type. Bacteria usually produce PHB upon availability of a carbon source and limitation of another essential nutrient. Therefore, it is widely believed that the function of PHB is to serve as a mobilizable carbon repository when bacteria face carbon limitation, supporting their survival. However, recent findings indicate that bacteria switch from PHB synthesis to mobilization under stress conditions such as thermal and oxidative shock. The mobilization products, 3-hydroxybutyrate and its oligomers, show a protective effect against protein aggregation and cellular damage caused by reactive oxygen species and heat shock. Thus, bacteria should have an environmental monitoring mechanism directly connected to the regulation of the PHB metabolism. Here, we review the current knowledge on PHB physiology together with a summary of recent findings on novel functions of PHB in stress resistance. Potential applications of these new functions are also presented. PHB cycle as a stress reliever in bacteria.