Bioresource Technology ( IF 9.7 ) Pub Date : 2023-11-14 , DOI: 10.1016/j.biortech.2023.130024
Susu Han 1 , Yibin Xue 1 , Qiaojuan Yan 2 , Zhengqiang Jiang 1 , Shaoqing Yang 1
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A chitinase (PbChi70) from Paenibacillus barengoltzii was engineered by directed evolution to enhance its hydrolysis efficiency towards powder chitin. Through two rounds of screening, a mutant (mPbChi70) with a maximum specific activity of 73.21 U/mg was obtained, which is by far the highest value ever reported. The mutant gene was further transformed into Aspergillus niger FBL-B (ΔglaA) which could secrete high level of endogenously β-N-acetylglucosaminidase (GlcNAcase), thus a two-enzyme expression system was constructed. The highest chitinase activity of 61.33 U/mL with GlcNAcase activity of 353.1 U/mL was obtained in a 5-L fermentor by high-cell density fermentation. The chitin-degrading enzyme cocktail was used for the bioconversion of GlcNAc from powder chitin directly, and the highest conversion ratio reached high up to 71.9 % (w/w) with GlcNAc purity ≥95 % (w/w). This study may provide an excellent chitinase as well as a double enzyme cocktail system for efficient biological conversion of chitin materials.
中文翻译:
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黑曲霉双酶系统的开发,用于从粉状甲壳素中高效生产 N-乙酰基-β-D-葡萄糖胺
来自Barengoltzii 类芽孢杆菌的几丁质酶 (PbChi70) 通过定向进化进行改造,以提高其对粉末几丁质的水解效率。通过两轮筛选,获得了最大比活性为73.21 U/mg的突变体(mPbChi70),这是迄今为止报道的最高值。将突变基因进一步转化至可分泌高水平内源β- N-乙酰氨基葡萄糖苷酶(GlcNAcase)的黑曲霉FBL-B(ΔglaA)中,构建双酶表达系统。在5L发酵罐中通过高细胞密度发酵获得了最高的几丁质酶活性61.33 U/mL和GlcNAcase活性353.1 U/mL。甲壳素降解酶混合物直接将粉末甲壳素生物转化为GlcNAc,最高转化率高达71.9%(w/w),GlcNAc纯度≥95%(w/w)。这项研究可能为甲壳素材料的高效生物转化提供一种优良的几丁质酶以及双酶混合物系统。