Miyazawa Ken, Yoshimi Akira, Zhang Silai, Sano Motoaki, Nakayama Mayumi, Gomi Katsuya, Abe Keietsu
a Laboratory of Applied Microbiology, Department of Microbial Biotechnology , Graduate School of Agricultural Science, Tohoku University , Sendai , Japan.
b Microbial Genomics Laboratory , New Industry Creation Hatchery Center, Tohoku University , Sendai , Japan.
Biosci Biotechnol Biochem. 2016 Sep;80(9):1853-63. doi: 10.1080/09168451.2016.1209968. Epub 2016 Jul 21.
Under liquid culture conditions, the hyphae of filamentous fungi aggregate to form pellets, which reduces cell density and fermentation productivity. Previously, we found that loss of α-1,3-glucan in the cell wall of the fungus Aspergillus nidulans increased hyphal dispersion. Therefore, here we constructed a mutant of the industrial fungus A. oryzae in which the three genes encoding α-1,3-glucan synthase were disrupted (tripleΔ). Although the hyphae of the tripleΔ mutant were not fully dispersed, the mutant strain did form smaller pellets than the wild-type strain. We next examined enzyme productivity under liquid culture conditions by transforming the cutinase-encoding gene cutL1 into A. oryzae wild-type and the tripleΔ mutant (i.e. wild-type-cutL1, tripleΔ-cutL1). A. oryzae tripleΔ-cutL1 formed smaller hyphal pellets and showed both greater biomass and increased CutL1 productivity compared with wild-type-cutL1, which might be attributable to a decrease in the number of tripleΔ-cutL1 cells under anaerobic conditions.
在液体培养条件下，丝状真菌的菌丝体会聚集形成菌球，这会降低细胞密度和发酵生产力。此前，我们发现构巢曲霉细胞壁中的α-1,3-葡聚糖缺失会增加菌丝的分散性。因此，我们在此构建了工业真菌米曲霉的一个突变体，其中编码α-1,3-葡聚糖合酶的三个基因被破坏（tripleΔ）。尽管tripleΔ突变体的菌丝没有完全分散，但该突变菌株形成的菌球比野生型菌株的小。接下来，我们通过将编码角质酶的基因cutL1转化到米曲霉野生型和tripleΔ突变体中（即野生型-cutL1、tripleΔ-cutL1），在液体培养条件下检测酶的生产力。与野生型-cutL1相比，米曲霉tripleΔ-cutL1形成的菌丝菌球更小，生物量更大，CutL1生产力也更高，这可能归因于厌氧条件下tripleΔ-cutL1细胞数量的减少。
