两株芽孢杆菌在苎麻纤维复合脱胶中的应用

Application of two Bacillus sp. strains in composite degumming of ramie fibers

摘要:

[背景] 苎麻纤维细长、强韧、洁白、有光泽，被誉为"天然纤维之王"，应用广泛。但其被以半纤维素和果胶为主要成分的胶质所包裹，脱胶是生产精干麻工艺的核心工序。利用单一菌株脱胶，往往因其脱胶酶系不全，存在胶质去除率低的问题，导致后期仍需要大量的碱和漂白剂处理。[目的] 丰富苎麻脱胶过程中关键酶系，从而提高苎麻胶质去除率，并降低脱胶后期化学试剂的用量，推进苎麻生物脱胶的工艺应用。[方法] 选用2株芽孢杆菌HG-9 （高果胶酶和甘露聚糖酶）和HG-25 （高木聚糖酶）建立了复合微生物脱胶技术，并对其进行了优化。[结果] 当2株菌接种量均为6%，水料比16：1，初始pH值5.9，在温度37.6℃下脱胶处理14 h时脱胶效果最佳，与菌株HG-9单独脱胶相比，脱胶时间减少2 h，胶质去除率、半纤维素去除率和木质素去除率分别提高9.32%、21.24%和17.93%，次氯酸钠用量减少20%。通过电子显微镜分析其形貌特征发现，混合脱胶获得的纤维表面更加平滑，无明显扭曲和损伤且纤维分散度较高。[结论] 通过复合微生物协同作用，丰富脱胶过程中关键酶系，提高了苎麻纤维胶质去除率，缩短了脱胶时间，而且减少了脱胶后期漂白剂的用量，为苎麻生物脱胶工业化应用的进一步发展提供了指导。

Abstract:

[Background] Ramie fiber is known as the "king of natural fiber" and used in many fields due to its excellent properties such as slender, strong, white, and shiny. However, the fiber is wrapped by the gum materials with hemicellulose and pectin as the main components, and degumming is the pivotal process for obtaining the refined ramie fibers. Using a single strain for ramie degumming, the gum removal rate is always low due to its incomplete degumming enzyme system. As a result, lots of alkalis and bleachers have to be used to remove the residual gum materials in the later stage. [Objective] Enriching the key enzyme systems in the degumming process of ramie fibers, improving the gum removal rate, reducing the usage of chemical reagents in the later stage, and promoting the industrial application of ramie biological degumming. [Methods] One strain Bacillus sp. HG-9 with highly activities of pectinase and mannanase and another Bacillus sp. HG-25 with highly activities of xylanase were selected to establish a mixed microbial degumming technology. Besides, the related parameters of the degumming process were optimized.[Results] When the inoculation amount of the two strains, the ratio of water to material, the initial pH value, the temperature, and the degumming time were 6%, 16:1, 5.9, 37.6℃, and 14 h, respectively, the effect was best. Compared with strain HG-9 alone, the degumming time was reduced by 2 h, and the removal rate of gums, hemicellulose, and lignin were increased by 9.32%, 21.24%, and 17.93%, respectively. The amount of sodium hypochlorite was reduced by 20%. The results of scanning electron microscopy showed that the fibers obtained by composite degumming was smoother, without obvious distortion and damage. Meanwhile, the fiber dispersion was high. [Conclusion] With the synergistic action of composite microorganisms, the key enzymes in the degumming process was enriched, the gum removal rate was improved, the degumming time and the amount of bleacher in the later stage was reduced. This study provided meaningful guidance for the further industrial application of ramie biological degumming.