Ultrastructural changes in prokaryotic microorganisms caused by long-term exposure to high salt and copper ion concentrations

abstract

English

Cupriavidus necator is a soil bacterium known as a producer of polyhydroxyalkanoates (PHA), polyesters of hydroxyalkanoic acids. PHAs are polymers present in many prokaryotic organisms in the form of intracellular granules and serve as a source of carbon in the cell. Moreover, recent studies indicate, that the presence of PHA in the microbial cells enhances their robustness against various stress factors. Polyhydroxyalkanoates also attract attention as a potential substitute for petrochemical plastics. These biopolymers have similar properties as for example polypropylene, but since they are biodegradable, they will decompose in nature incomparably faster than conventional plastic materials. In our study, we focused on the PHA producer Cupriavidus necator in a long-term experiment, where the bacterial cells were exposed to high concentrations of salt (54 passages) and copper ions (64 passages). After cultivation, bacterial cells were harvested and analysed using the methods of electron microscopy, namely cryo-SEM and TEM. In the TEM images of Cu stress, it is possible to observe dense precipitates inside of the cells which can be correlated to cryo-SEM images where cells exposed to Cu+ show small hollows in the cytoplasm of similar shape and size as precipitates in TEM imaging. Also, cells exposed to high osmotic stress appeared to be smaller, than the control cultivation without any stress factors, and of a crescent shape. These findings indicate, that long-term exposure of microbial cells to stress conditions changes not only the production of intracellular polymers but also their morphology and this phenomenon deserves to be studied further.

Cupriavidus necator; polyhydroxyalkanoates; long-term stress; TEM; cryo-SEM.

MRÁZOVÁ, K.; NOVÁČKOVÁ, I.; HRUBANOVÁ, K.; NEBESÁŘOVÁ, J.; OBRUČA, S.; KRYŽÁNEK, V.

4. 9. 2022

Czechoslovak Microscopy Society

Brno

978-80-11-02253-2

16MCM: Book of Abstracts

231

232

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