TY  - JOUR
U1  - Zeitschriftenartikel, wissenschaftlich - begutachtet (reviewed)
A1  - Godard, Thibault
A1  - Zühlke, Daniela
A1  - Richter, Georg
A1  - Wall, Melanie
A1  - Rohde, Manfred
A1  - Riedel, Katharina
A1  - Poblete-Castro, Ignacio
A1  - Krull, Rainer
A1  - Biedendieck, Rebekka
T1  - Metabolic Rearrangements Causing Elevated Proline and Polyhydroxybutyrate Accumulation During the Osmotic Adaptation Response of Bacillus megaterium
JF  - Frontiers in Bioengineering and Biotechnology
N2  - For many years now, Bacillus megaterium serves as a microbial workhorse for the high-level production of recombinant proteins in the g/L-scale. However, efficient and stable production processes require the knowledge of the molecular adaptation strategies of the host organism to establish optimal environmental conditions. Here, we interrogated the osmotic stress response of B. megaterium using transcriptome, proteome, metabolome, and fluxome analyses. An initial transient adaptation consisted of potassium import and glutamate counterion synthesis. The massive synthesis of the compatible solute proline constituted the second longterm adaptation process. Several stress response enzymes involved in iron scavenging and reactive oxygen species (ROS) fighting proteins showed higher levels under prolonged osmotic stress induced by 1.8 M NaCl. At the same time, the downregulation of the expression of genes of the upper part of glycolysis resulted in the activation of the pentose phosphate pathway (PPP), generating an oversupply of NADPH. The increased production of lactate accompanied by the reduction of acetate secretion partially compensate for the unbalanced (NADH/NAD+) ratio. Besides, the tricarboxylic acid cycle (TCA) mainly supplies the produced NADH, as indicated by the higher mRNA and protein levels of involved enzymes, and further confirmed by 13C flux analyses. As a consequence of the metabolic flux toward acetyl-CoA and the generation of an excess of NADPH, B. megaterium redirected the produced acetyl-CoA toward the polyhydroxybutyrate (PHB) biosynthetic pathway accumulating around 30% of the cell dry weight (CDW) as PHB. This direct relation between osmotic stress and intracellular PHB content has been evidenced for the first time, thus opening new avenues for synthesizing this valuable biopolymer using varying salt concentrations under non-limiting nutrient conditions.
KW  - -
KW  - osmotic stress adaptation
KW  - transcriptomics
KW  - proteomics
KW  - flux analysis
KW  - proline
KW  - polyhydroxybutyrate (PHB)
Y1  - 2020
UN  - https://nbn-resolving.org/urn:nbn:de:gbv:9-opus-35580
SN  - 2296-4185
SS  - 2296-4185
U6  - https://doi.org/10.3389/fbioe.2020.00047
DO  - https://doi.org/10.3389/fbioe.2020.00047
VL  - 8
PB  - Frontiers Media S.A.
ER  -