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Biotransformation of keratin waste to amino acids and active peptides based on cell-free catalysis.
Biotechnology for Biofuels ( IF 6.3 ) Pub Date : 2020-04-01 , DOI: 10.1186/s13068-020-01700-4
Zheng Peng 1, 2 , Xinzhe Mao 1, 2 , Juan Zhang 1, 2 , Guocheng Du 1, 2 , Jian Chen 1, 3
Affiliation  

Background Keratin is the primary constituent of the vertebrate epidermis and epidermal appendages, as well as the main waste product generated during poultry processing from feathers, hair, scales, nails, etc. Keratin is generally hard, stubborn and difficult to hydrolyze; however, it is also inexpensive and contains more than 85% protein. Currently, tens of millions of tons of keratin waste are produced each year worldwide; however, no effective methods for the recovery of keratin waste have been reported thus far, making such research urgent. Keratinase has been reported to be useful for keratin waste recovery; however, nearly all keratinases are unable to hydrolyze keratin after they are detached from living cell systems. This may be due to low keratinase activity and lack of synergistic factors. Results Herein, the keratinase gene from Bacillus licheniformis BBE11-1 was successfully expressed in Bacillus subtilis WB600, allowing for improved activity of the recombinant keratinase KerZ1 to 45.14 KU/mL via promoter substitution and screening of the ribosome-binding sites. Further, real-time control of temperature, pH, dissolved oxygen, and feed strategy allowed the activity of KerZ1 to reach 426.60 KU/mL in a 15-L fermenter, accounting for a 3552-fold increase compared to the wild-type keratinase (120.1 U/mL). Most importantly, we proposed a method based on the synergistic action of keratinase KerZ1 and sodium sulfite, to hydrolyze feathers into amino acids. In specific, 100 g/L of feather waste can be successfully converted into 56.6% amino acids within 12 h, while supporting the production of dozens of bioactive peptides. Conclusions The activity of recombinant keratinase can be greatly enhanced via transcription and translational regulation in Bacillus subtilis. The synergistic action of keratinase and sulfite can rapidly degrade feather waste and produce amino acids and polypeptides.

中文翻译:

基于无细胞催化将角蛋白废物生物转化为氨基酸和活性肽。

背景角蛋白是脊椎动物表皮和表皮附件的主要成分,也是家禽加工过程中羽毛、毛发、鳞片、指甲等产生的主要废物。然而,它也很便宜,并且含有超过 85% 的蛋白质。目前,全球每年产生数千万吨角蛋白废物;然而,到目前为止,还没有关于回收角蛋白废物的有效方法的报道,这使得这项研究变得紧迫。据报道,角蛋白酶可用于角蛋白废物的回收;然而,几乎所有的角蛋白酶在它们脱离活细胞系统后都不能水解角蛋白。这可能是由于角蛋白酶活性低和缺乏协同因素。结果在此,来自地衣芽孢杆菌 BBE11-1 的角蛋白酶基因在枯草芽孢杆菌 WB600 中成功表达,通过启动子替换和核糖体结合位点筛选,使重组角蛋白酶 KerZ1 的活性提高到 45.14 KU/mL。此外,对温度、pH、溶解氧和补料策略的实时控制使 KerZ1 在 15 L 发酵罐中的活性达到 426.60 KU/mL,与野生型角蛋白酶相比增加了 3552 倍。 120.1 单位/毫升)。最重要的是,我们提出了一种基于角蛋白酶KerZ1和亚硫酸钠协同作用的方法,将羽毛水解成氨基酸。具体而言,100 g/L的羽毛废料可在12小时内成功转化为56.6%的氨基酸,同时支持数十种生物活性肽的生产。结论 重组角蛋白酶的活性可通过枯草芽孢杆菌的转录和翻译调控而大大增强。角蛋白酶和亚硫酸盐的协同作用可以快速降解羽毛废料并产生氨基酸和多肽。
更新日期:2020-04-22
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