Research On The Biological Degumming Of Apocynum Fiber Based On The Breaking Of The Resistant Barrier Structure

Apocynum venetum natural functional fabric is popular in recent years,but the traditional chemical degumming process is so seriously polluted that it does not conform to the sustainable development route.Therefore,efficient and clean degumming method is the key to the development of Apocynum venetum fiber products.Biodegumming,the most ideal way to extract fiber from the bast,but it has not been totally applied in produce,because of the low efficiency and unstable degumming effect.A large number of researches have been focused on the selection of degumming strains.However,biodegumming is a process which the key degumming enzyme combine with the gum substrate in phloem to catalyze decomposition.Therefore,this paper innovatively focuses on the composition and structure of the phloem.In order to improve the biodegumming effect,the general rules were explored in the selection of phloem,the breakage of bio-recalcitrance,the selection of degumming strains and the optimization of fermentation technology.The influence of different varieties,harvesting time and plant position on the grade of maturity of Apocynum venetum phloem were analyzed,and the biodegumming effect of phloem with different maturity grade was investigated.The results showed that different varieties of Apocynum venetum bast had different maturity grade at the same growth time.The later the harvest time was,the higher the bast maturity was.And the maturity of phloem root was higher than that of the middle and the tip.High maturity bast was difficult to be degummed by microorganism.The phloem suitable for biodegumming was determined in the end.The pretreatment of Apocynum venetum bast was investigated for breaking the bio-recalcitrance.The effects of physic,chemical and biological pretreatment on the bast structure and microbial were investigated.The results showed that pretreatment removed part of gum,the burden of biodegumming was reduced.In addition pretreatment increased the specific surface area of Apocynum venetum bast.Finally after pretreatment and biodegumming the residual gum content of Apocynum venetum fiber decreased by 13.5-26.3%.Different pretreatment methods had different effects on the bast structure and biodegumming process.Research showed that hand scotching,alkaline pretreatment and oxidation pretreatment were suitable for Apocynum venetum bast biodegumming.Strains with strong ability of gum degradation were screened.They were pectin-degrading microorganism p3,xylan-degrading microorganism x2 and glucomannan-degrading microorganism g3.Next the degradation ability of gum and resistance ability to polyphenols in the Apocynum venetum phloem of three strains were improved by evolutionary engineering.In addition the mixed bacteria fermentation method of degumming was adopted and the fermentation conditions were optimized by response surface method.Under the optimal condition,the weight loss rate of Apocynum venetum fiber after biodegumming was 29.1%.By comparison,the residual gum content,closed filaments percentage and bundle fiber breaking strength of biodegummed fiber were higher than that of chemical degummed fiber.