Different control mechanisms regulate glucoamylase and protease gene transcription in Aspergillus oryzae in solid-state and submerged fermentation

Abstract

Solid-state fermentation (SSF) with Aspergillus oryzae results in high levels of secreted protein. However, control mechanisms of gene expression in SSF have been only poorly studied. In this study we show that both glucoamylase (glaB) and protease (alpA, nptB) genes are highly expressed during surface cultivation on wheatbased solid medium, and even higher during cultivation on wheat kernels. In wheat-based liquid medium, low levels of gene expression are observed. Typical SSF cultivation conditions, such as low water activity and the formation of aerial hyphae, did not contribute to the high-level gene expression on wheat-based solid medium. Analysis of wheat-based solid and liquid cultivations showed differences in carbon and nitrogen utilisation and external pH. The results presented show that the difference in regulation of transcription of the alpA and nptB genes in wheatbased liquid and solid medium could be pH dependent, involving a pH-dependent transcription regulator. The results obtained suggest that the difference in regulation of transcription of the glaB gene in wheat-based liquid and solid medium is caused by a difference in carbohydrate degradation and consumption under the different culture conditions.

Adjunctive Application of Solid-State Culture Products from Aspergillus Oryzae for Semi-Hard Cheese

“…Traditional fermentation of A. oryzae on steamed rice, wheat or soybean generally occurs at 30~35ºC and pH 6.0~6.5 [5,6] and suitable strains have been selected depending on their purpose. In general, solid-phase media is superior to submerged culture for enzyme production by A. oryzae [7][8][9], and some enzymes are exclusively produced by solid-state cultivation [10].…”

Monitoring Global Gene Expression of Proteases and Improvement of Human Lysozyme Production in thenptBGene Disruptant ofAspergillus oryzae

“…It has been reported that transcription of these secretory protease genes was induced when the culture pH changed to neutral pH from acidic pH, suggesting that their transcription is regulated by pH. 20) Our DNA microarray data indicate that the pacC transcript, encoding a transcription factor required for alkaline adaptation, 21) was up-regulated more than 2-fold in the late phase (data not shown), in which pH recovery to neutral was observed (Fig. 1A).…”

A fungal biofilm reactor based on metal structured packing improves the quality of a Gla::GFP fusion protein produced by Aspergillus oryzae

“…Plasmid pAB4.1 (Hartingsveldt et al 1987) containing the Aspergillus niger pyrG mutant was used as the source of the selection marker. The glucoamylase B gene (glaB) was shown to be highly expressed during solid-state cultivation (Te Biesebeke et al 2005a). Therefore, an expression vector was generated based on glaB expression signals.…”