The transcriptional response of bioreactor-grown Aspergillus niger cultures towards three oils

ABSTRACT: The industrially important fungus Aspergillus niger feeds naturally on decomposing plant material, for which it is equipped with a range of enzyme systems. A significant proportion of plant material are lipids that might be available either as for energy storage or as membrane building blocks. With 63 potential lipase-encoding genes in its genome, A. niger has the tools to degrade these extracellular lipids. In contrast to polysaccharide-degrading enzyme networks not much is known about the signalling and regulatory processes that control lipase expression and activity in fungi both under laboratory and natural occurring conditions. A pulse of 1 mM of various oils was applied to four bioreactor-grown A. niger cultures to examine (i) whether A. niger responds at the level of gene transcription, (ii) at what time point this effect is detected most accurately, and (iii) whether differences between the response towards oils are observed. The triglyceride olive oil induces genes encoding peroxins and enzymes of fatty acid metabolism. A complex oil mixture extracted from wheat gluten, which is enriched for digalactosyl-diglycerides, induces genes encoding peroxins as well as enzymes of fatty acid metabolism, but with different expression profile when compared to olive oil. Pure digalactosyldiglyceride, a proxy for plant membrane lipids, does not trigger a transcriptional response. Keywords: time course; induction experiment In one week, 4 fermentor cultures were run in 2.2-liter batch fermentors in which A. niger was grown on 100 mM sorbitol. At 14 hours after oxygen supply had switched from headspace to sparger-inlet each fermentor was induced with 22 mL medium which contained 100 mM (final concentration in fermentor: 1 mM) of either olive oil, a complex oil mixture extracted from wheat gluten, pure wheat digalactosyldiglycerides, or was induced with a solution of minimal medium containing only 0.2% (in fermentor, final concentration 0.002%) triton X-100 which served as emulsifier agent. For each fermentor vessel, a sample of 10 mL was taken prior to induction (T=0), or 30 minutes, 1 hour, or 2 hours after induction. Every sample was hybridized onto a single microarray, yielding in total 16 DNA microarrays.

ORGANISM(S): Aspergillus niger

SUBMITTER: Leo De Graaff 

PROVIDER: E-GEOD-14285 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress