Invasive growth of Aspergillus oryzae in rice koji and increase of nuclear number
Background: ‘Rice koji’ is a solid culture of Aspergillus oryzae on steamed rice grains. Multiple parallel fermentation, wherein saccharification of rice by A. oryzae and alcohol fermentation by the budding yeast occur simultaneously, lead to the formation of a variety of ingredients of Japanese sake. In sake brewing, the degree of mycelial invasive growth into the steamed rice, called ‘haze-komi’, highly correlates with the digestibility and quality of rice koji, since the hyphae growing into the rice secrete amylases and digest starch of rice.
Results: In this study, we investigated mycelial distribution of GFP-tagged A. oryzae in rice koji made with different types of rice, such as sake rice and eating rice, with 50 or 90% polishing rate to remove abundant proteins and lipids near the surface. In addition, we compared transcriptomes of A. oryzae in the different types of rice koji. Finally, we found that A. oryzae increases the nuclear number and hyphal width in the course of 1-3 days cultivation.
Conclusions: Our imaging analyses indicate that A. oryzae hyphae grew more deeply into 50% polished rice than 90% polished rice. The increases of nuclear number may be a selectively acquired characteristic for the high secretory capacity during the breeding in long history.
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Posted 19 May, 2020
On 17 May, 2020
On 06 May, 2020
On 05 May, 2020
On 05 May, 2020
On 25 Mar, 2020
Received 22 Mar, 2020
On 27 Feb, 2020
Received 24 Feb, 2020
On 19 Feb, 2020
Invitations sent on 17 Feb, 2020
On 28 Jan, 2020
On 28 Jan, 2020
On 27 Jan, 2020
On 27 Jan, 2020
Invasive growth of Aspergillus oryzae in rice koji and increase of nuclear number
Posted 19 May, 2020
On 17 May, 2020
On 06 May, 2020
On 05 May, 2020
On 05 May, 2020
On 25 Mar, 2020
Received 22 Mar, 2020
On 27 Feb, 2020
Received 24 Feb, 2020
On 19 Feb, 2020
Invitations sent on 17 Feb, 2020
On 28 Jan, 2020
On 28 Jan, 2020
On 27 Jan, 2020
On 27 Jan, 2020
Background: ‘Rice koji’ is a solid culture of Aspergillus oryzae on steamed rice grains. Multiple parallel fermentation, wherein saccharification of rice by A. oryzae and alcohol fermentation by the budding yeast occur simultaneously, lead to the formation of a variety of ingredients of Japanese sake. In sake brewing, the degree of mycelial invasive growth into the steamed rice, called ‘haze-komi’, highly correlates with the digestibility and quality of rice koji, since the hyphae growing into the rice secrete amylases and digest starch of rice.
Results: In this study, we investigated mycelial distribution of GFP-tagged A. oryzae in rice koji made with different types of rice, such as sake rice and eating rice, with 50 or 90% polishing rate to remove abundant proteins and lipids near the surface. In addition, we compared transcriptomes of A. oryzae in the different types of rice koji. Finally, we found that A. oryzae increases the nuclear number and hyphal width in the course of 1-3 days cultivation.
Conclusions: Our imaging analyses indicate that A. oryzae hyphae grew more deeply into 50% polished rice than 90% polished rice. The increases of nuclear number may be a selectively acquired characteristic for the high secretory capacity during the breeding in long history.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7