香云纱染整技艺机理解析及铁还原菌对过乌用泥的强化作用

Mechanism of dyeing technique of Xiang-yun-sha and bioaugmentation of its coating mud with iron reducing bacteria

具有六百多年传承历史的香云纱染整技艺是一种同时结合植物染(过薯莨)和矿物染(过乌)的独特纯手工染整工艺,已被列入国家级非物质文化遗产,但香云纱染整技艺的科学机理尚未被系统解析.本研究采用电离喷雾高分辨质谱和红外光谱等分析方法,分析了薯莨色素的组成成分和结构,探究了其与丝蛋白的相互作用机制;通过化学模拟法从分子层面解析了"过乌"工艺的化学机理,并考察了微生物对"过乌"河泥特性的维护作用.结果表明:薯莨色素中同时存在儿茶素类缩合单宁酚和醌两种结构,其通过多位点氢键与丝蛋白肽键结合;曝晒后向阳面胶质色素进一步与河泥中Fe(II)反应形成溶解态缩合单宁络合物,并快速被氧化形成含Fe(III)的黑色沉淀,最终形成一面乌黑发亮一面棕色的香云纱.并发现微生物的铁还原作用是保障"过乌"河泥质量和呈现香云纱经典特色的关键,通过添加具有铁还原功能的希瓦氏菌S12可以显著改善不合格"过乌"用泥的染色性能.本研究的结果对保障我国古老的香云纱染整技艺的传承和推动该产业的规范化生产提供了可靠的科学理论支撑.

The dyeing technique of Xiang-yun-sha, with a history of more than 600 years, is a kind of unique hand-made dyeing process that combines both plant dyeing（immersed with Juliang extract） and mineral dyeing（mud coating）. It has been included in the national intangible cultural heritage. However, the scientific mechanism of this heritage has not been systematically explained. In this study,the composition and structure of Juliang were analyzed with ionizing-spray high-resolution mass spectrometry and infrared spectroscopy, and the interaction mechanism of the Juliang with silk protein was explored. The mud-coating process was explained from the molecular level through a chemical simulation method, and the maintenance effect of microbes on characteristics of river mud was examined. Results showed that there are phenol and quinone of catechin condensed tannin in the Juliang extract, and they were combined with silk protein peptide bonds through multi-sites hydrogen bonds. The gial pigments on the silk surface after exposure further reacted with Fe（II） in the mud to form soluble condensed tannin complex, and then this complex was rapidly oxidized to form black precipitate containing Fe（III）. Eventually, lustrous dark brown was formed on sun side, brown on the other side. Further, it was found that microbial iron reduction played a key role on maintaining the mud properties, because the addition of Shewanella decolorationis S12 with iron reducing function can significantly improve the dyeing performance of unqualified mud.This study provides reliable scientific support to protect inheritance of dyeing technique and promote the standardized production of the industry.