Biotechnologically Relevant Enzymes and Proteins

Applied Microbiology and Biotechnology

, Volume 92, Issue 5, pp 961-969

First online:

Identification of potential cell wall component that allows Taka-amylase A adsorption in submerged cultures of Aspergillus oryzae

  • Hiroki SatoAffiliated withLaboratory of Bioindustrial Genomics, Graduate School of Agricultural Science, Tohoku University
  • , Yoshiyuki ToyoshimaAffiliated withLaboratory of Bioindustrial Genomics, Graduate School of Agricultural Science, Tohoku UniversityYamasa Shoyu Co. Ltd.
  • , Takahiro ShintaniAffiliated withLaboratory of Bioindustrial Genomics, Graduate School of Agricultural Science, Tohoku University
  • , Katsuya GomiAffiliated withLaboratory of Bioindustrial Genomics, Graduate School of Agricultural Science, Tohoku University Email author 

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Abstract

We observed that α-amylase (Taka-amylase A; TAA) activity in the culture broth disappeared in the later stage of submerged cultivation of Aspergillus oryzae. This disappearance was caused by adsorption of TAA onto the cell wall of A. oryzae and not due to protein degradation by extracellular proteolytic enzymes. To determine the cell wall component(s) that allows TAA adsorption efficiently, the cell wall was fractionated by stepwise alkali treatment and enzymatic digestion. Consequently, alkali-insoluble cell wall fractions exhibited high levels of TAA adsorption. In addition, this adsorption capacity was significantly enhanced by treatment of the alkali-insoluble fraction with β-glucanase, which resulted in the concomitant increase in the amount of chitin in the resulting fraction. In contrast, the adsorption capacity was diminished by treating the cell wall fraction with chitinase. These results suggest that the major component that allows TAA adsorption is chitin. However, both the mycelium and the cell wall demonstrated the inability to allow TAA adsorption in the early stage of cultivation, despite chitin content in the cell wall being identical in both early and late stages of cultivation. These results suggest the existence of unidentified factor(s) that could prevent the adsorption of TAA onto the cell wall. Such factor(s) is most likely removed or diminished from the cell wall following longer cultivation periods.

Keywords

Aspergillus oryzae α-Amylase Cell wall Chitin Submerged culture Protein production