Accumulation of Poly(3-hydroxybutyrate) Helps Bacterial Cells to Survive Freezing

Accumulation of polyhydroxybutyrate (PHB) seems to be a common metabolic strategy adopted by many bacteria to cope with cold environments. This work aimed at evaluating and understanding the cryoprotective effect of PHB. At first a monomer of PHB, 3-hydroxybutyrate, was identified as a potent cryoprotectant capable of protecting model enzyme (lipase), yeast (Saccharomyces cerevisiae) and bacterial cells (Cupriavidus necator) against the adverse effects of freezing-thawing cycles. Further, the viability of the frozen-thawed PHB accumulating strain of C. necator was compared to that of the PHB non-accumulating mutant. The presence of PHB granules in cells was revealed to be a significant advantage during freezing. This might be attributed to the higher intracellular level of 3-hydroxybutyrate in PHB accumulating cells (due to the action of parallel PHB synthesis and degradation, the so-called PHB cycle), but the cryoprotective effect of PHB granules seems to be more complex. Since intracellular PHB granules retain highly flexible properties even at extremely low temperatures (observed by cryo-SEM), it can be expected that PHB granules protect cells against injury from extracellular ice. Finally, thermal analysis indicates that PHB-containing cells exhibit a higher rate of transmembrane water transport, which protects cells against the formation of intracellular ice which usually has fatal consequences.
Akumulace polyhydroxybutyrate (PHB) se zdá být společnou metabolickou strategií adoptovanou mnoha bakteriemi za účelem odolat chladnému prostředí. Cílem této práce bylo pochopení kryoprotektivního účinku PHB. Monomer PHB - 3-hydroxybutyrát, byl identifikován jako silný protektant schopný chránit enzymy, kvasinky (Saccharomyces cerevisiae) a bakteriální buňky (Cupriavidus necator) proti nepříznivým účinkům cyklů zmrazování rozmrazování.

Keywords

Polyhydroxybutyrát, 3-hydroxybutyrát, kryoprotektanty, voda vnitrobuněčná, stresová odpověď, Polyhydroxybutyrate, 3-hydroxybuyrate, cryoprotectants, intracellular water, stress response

Citation

PLOS ONE. 2016, vol. 11, issue 6, p. 1-16.
http://europepmc.org/articles/PMC4912086?pdf=render

Document type

Peer-reviewed

Document version

Published version

Language of document

en

Document licence

Creative Commons Attribution 4.0 International
http://creativecommons.org/licenses/by/4.0/