Su Chang, Gong Jin-Song, Wu Ze-Xi, Liu Yan-Ling, Li Heng, Shi Jin-Song, Xu Zheng-Hong
Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Life Sciences and Health Engineering, Jiangnan University, Wuxi, Jiangsu 214122, PR China.
National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, PR China.
J Agric Food Chem. 2023 Feb 8;71(5):2421-2429. doi: 10.1021/acs.jafc.2c07624. Epub 2023 Jan 11.
Keratinases specifically degrade insoluble keratin waste, thus contributing to environmental protection and sustainable biomass development. However, their industrial application is hindered by inefficient enzyme production and poor biomass generation. In this study, the heterologous expression of keratinase was found to have cytotoxicity and might block host cell growth due to its proteolytic property. To address this problem, an autoregulatory expression system based on quorum sensing was developed to synergistically regulate cell growth and keratinase production in . The growth-dependent promoter P was chosen and shown to be effective in delaying keratinase production while promoting host cell proliferation. Copy number screening and core region mutations further balanced the two states. Carbon supplement optimization indicated that addition of 2% glucose facilitated biomass accumulation during the early stage of fermentation. Cell density increased to 15.6 (OD) from 8 with keratinase activity raised to 4200 U·mL from 1162 U·mL. Keratinase was then utilized in the bioconversion of feather waste to prepare soluble keratins, polypeptides, and amino acids. This study provides a powerful system for efficient production of keratinase and paves the way for keratin waste recycling.
角蛋白酶能特异性降解不溶性角蛋白废物，从而有助于环境保护和可持续生物质发展。然而，其工业应用受到酶产量低和生物质产量低的阻碍。在本研究中，发现角蛋白酶的异源表达具有细胞毒性，可能因其蛋白水解特性而阻碍宿主细胞生长。为了解决这个问题，开发了一种基于群体感应的自动调节表达系统，以协同调节细胞生长和角蛋白酶在……中的产生。选择了生长依赖性启动子P，结果表明它在延迟角蛋白酶产生的同时促进宿主细胞增殖方面是有效的。拷贝数筛选和核心区域突变进一步平衡了这两种状态。碳源补充优化表明，添加2%葡萄糖有助于发酵早期的生物质积累。细胞密度从8增加到15.6（OD），角蛋白酶活性从1162 U·mL提高到4200 U·mL。然后将角蛋白酶用于羽毛废物的生物转化，以制备可溶性角蛋白、多肽和氨基酸。本研究为高效生产角蛋白酶提供了一个强大系统，并为角蛋白废物回收铺平了道路。
