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Involvement of polyhydroxyalkanoates in stress response of thermophilic bacterium Schlegelella thermodepolymerans
Berger, Matyáš ; Nováčková, Ivana (referee) ; Slaninová, Eva (advisor)
This bachelor's thesis is focused on investigating the effect of different stress factors on the bacteria Schlegelella thermodepolymerans, which is capable of producing polyhydroxyalkanoates. In this case, in the form of poly(3-hydroxybutyrate). The selected stress factors were temperature shock, repeated freezing and defrosting. The last stress factor was osmotic stress, caused by sodium chloride solutions of different concentrations. In the theoretical part, polyhydroxyalkanoates, thermophilic organisms, mechanisms of individual stresses and methods of analysis of polyhydroxyalkanoates were characterized. In the experimental part, two strains of the thermophilic bacteria Schlegelella thermodepolymerans were compared, namely M 15344 and DSM 15344. The stress resistance of both strains was compared by measuring viability using flow cytometry. During the measurement, the increase in optical density was monitored, and the content of P(3HB) in the biomass was determined using GC-FID. Morphological changes caused by stresses were observed using Cryo-SEM and STEM electron microscopy methods. The DSM 15344 strain showed better growth and P(3HB) production than the M 15344 strain, which, on the other hand, showed better stress resistance.
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