Invasive growth of Aspergillus oryzae in rice koji and increase of nuclear number
Invasive growth of Aspergillus oryzae in rice koji and increase of nuclear number
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DOI：
10.1186/s40694-020-00099-9
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发表时间：
2020-06-05
影响因子：
--
通讯作者：
Takeshita, Norio
中科院分区：
文献类型：
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作者：
Yasui, Mizuki;Oda, Ken;Takeshita, Norio
背景：“米曲”是米曲霉在蒸过的米粒上的固体培养物。稻曲霉对大米的糖化和出芽酵母的酒精发酵同时进行的多重平行发酵，形成了日本清酒的多种成分。在清酒酿造中，菌丝侵入大米的程度，称为“雾米”，与大米曲的消化率和质量高度相关，因为生长在大米中的菌丝分泌淀粉酶和消化淀粉。结果：在本研究中，我们研究了gfp标记的米曲菌在以不同类型的米（如清米和食米）制作的米曲中的菌丝分布，抛光率为50%或90%，以去除表面附近丰富的蛋白质和脂质。此外，我们还比较了稻曲霉在不同类型稻曲中的转录组。最后，我们发现在1 ~ 3天的培养过程中，米芽孢杆菌的核数和菌丝宽度都有所增加。结论：成像分析表明，稻瘟病菌菌丝在50%精米中的生长深度大于90%精米。核数的增加可能是该物种在长期的栽培历史中选择性获得的高分泌能力的特征。
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, leads 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. 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 long history of cultivation of this species.