A high-efficiency and eco-friendly degumming process for ramie fibers

Degumming is the most critical step in the preparation of ramie fibers for textile application. However, the traditional chemical degumming process, which uses large amounts of alkali at high temperature, has been a severe challenge to the environment. In this study, a bacterial strain Pectobacterium carotovorum HG-49, was isolated and successfully applied to the degumming of ramie fibers at an industrial scale. The gum removal ratio can reach 82.16% within 16 h of degumming, which is more efficient than most reported methods. Analyses of changes in bacterial populations and community structures over the degumming process showed that strain HG-49 is the dominant bacteria at all time points with a lmaximum concentration of 2.17 x 10(9) CFU/mL at 12 h. The maximum activities of pectinase, mannanase, and xylanase reached 110.89, 39.89, and 32.17 U/mL at 10-12 h, respectively. The residual gum content of refined ramie fibers decreased to 1.85% after degumming, and their bundle breaking tenacity and whiteness reached 5.03 cN/dtex and 52, respectively. These values exceed the first-class standards of China textile criteria. Scanning Electron Microscopy (SEM) and Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR FT-IR) analysis further confirmed the excellent degumming effects of the proposed method. The whole genome sequencing of strain HG-49 was completed, and 28 degumming enzyme genes were found, which explains its high-efficiency degumming abilities. Moreover, because the method abandons the use of acid and greatly reduces alkali consumption, it is eco-friendly. This study provides a promising cleaner degumming method for the ramie textile industry. (C) 2020 Elsevier Ltd. All rights reserved.