Gao Ruijie, Deng Huaxiang, Guan Zhengbing, Liao Xiangru, Cai Yujie
Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, China.
AMB Express. 2018 May 2;8(1):71. doi: 10.1186/s13568-018-0597-0.
Shiraia bambusicola is an important and valuable macrofungus and hypocrellins are its main secondary metabolites which have been widely applied in many medical fields. However, during SSF process of this filamentous fungus, use ratio of corn substrate and dissolved oxygen supply are two main limiting factors, which influence production cost, yield and product quality. To solve these problems, overexpressions of amy365-1 and vgb in S. bambusicola were investigated and three overexpression transformants were constructed. Results demonstrated that expressions and coexpression of AMY365-1 and VHb not only increased the productions of biomass, amylase, hypocrellin, but also up-regulated relative expression levels of four central carbon metabolism genes (pdc, ald, acs, acc) and seven hypocrellin biosynthesis genes (fad, mono, zftf, omef, msf, pks, mco). Furthermore, expression of VHb decreased SSF period. When amy365-1 and vgb were coexpressed, relative expression levels of zftf and pks reached their highest levels at 72 h under liquid fermentation, hypocrellin production reached the highest level 75.85 mg/gds which was 2.99-fold compared with wild type strain within 11 days under SSF, and residual starch of solid substrates was decreased from 35.47 to 14.57%.
竹黄是一种重要且有价值的大型真菌，竹红菌素是其主要的次生代谢产物，已广泛应用于许多医学领域。然而，在这种丝状真菌的固态发酵过程中，玉米底物的利用率和溶解氧供应是两个主要限制因素，它们会影响生产成本、产量和产品质量。为了解决这些问题，研究了amy365 - 1和vgb在竹黄中的过表达情况，并构建了三个过表达转化体。结果表明，AMY365 - 1和VHb的表达及共表达不仅增加了生物量、淀粉酶、竹红菌素的产量，还上调了四个中心碳代谢基因（pdc、ald、acs、acc）和七个竹红菌素生物合成基因（fad、mono、zftf、omef、msf、pks、mco）的相对表达水平。此外，VHb的表达缩短了固态发酵周期。当amy365 - 1和vgb共表达时，在液体发酵72小时时，zftf和pks的相对表达水平达到最高，在固态发酵11天内，竹红菌素产量达到最高水平75.85 mg/gds，是野生型菌株的2.99倍，固体底物的残余淀粉从35.47%降至14.57%。
