Mysterious Amorphous State of Native Granules of Polyhydroxyalkanoates and Its Transitions Into Crystalline State

Mysterious Amorphous State of Native Granules of Polyhydroxyalkanoates and Its Transitions Into Crystalline State

Abstract

Polyhydroxyalkanoates (PHA) are hydrophobic polyesters of hydroxyalkanoic acids produced and accumulated by numerous microorganisms in form of intracellular granules. Surface of the granules is covered by the layer of proteins which serve as a border between hydrophobic PHA and aqueous cytoplasm. Bacteria cells are producing and degrading this polymer simultaneously. Therefore, even where the content of polymer reaches up to 90%wt of cellular dry matter, the cell maintains also the concentration of monomer on a significant level. The role of PHA is not only as carbon or energy storage but due to our previous findings, the PHA has also protective effect on bacteria cells of Cupriavidus necator H16 against temperature, UV, osmotic stress etc. These all stunning properties are closely associated with its physical amorphous character. It can be assumed that the granules maintain its amorphous state thanks to presence of low molecular plasticizers (e.g. water, monomer molecules) despite of thermodynamical unfavorability of this arrangement.

Polyhydroxyalkanoates (PHA) are hydrophobic polyesters of hydroxyalkanoic acids produced and accumulated by numerous microorganisms in form of intracellular granules. Surface of the granules is covered by the layer of proteins which serve as a border between hydrophobic PHA and aqueous cytoplasm. Bacteria cells are producing and degrading this polymer simultaneously. Therefore, even where the content of polymer reaches up to 90%wt of cellular dry matter, the cell maintains also the concentration of monomer on a significant level. The role of PHA is not only as carbon or energy storage but due to our previous findings, the PHA has also protective effect on bacteria cells of Cupriavidus necator H16 against temperature, UV, osmotic stress etc. These all stunning properties are closely associated with its physical amorphous character. It can be assumed that the granules maintain its amorphous state thanks to presence of low molecular plasticizers (e.g. water, monomer molecules) despite of thermodynamical unfavorability of this arrangement.

Polyhydroxyalkanoates; intracellular granules; amorphous state; bacterial cells

Polyhydroxyalkanoates; intracellular granules; amorphous state; bacterial cells

SLANINOVÁ, E.; SEDLÁČEK, P.; OBRUČA, S.

2019

16.04.2018

978-80-86238-83-8

1

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