Study On The Bacterial Consortium Of Ramie Degumming

Ramie is an excellent natural fiber material,with a unique long fiber length,moisture absorption,and quick release.The ramie raw hemp usually contains about 33% of non-fibrous components,and only after these non-fibrous components are removed can industry requirements be met.Traditional chemical degumming methods are not suitable for the needs of today's society because of the shortcomings of pollution.The degumming of biotechnology due to low pollution and mild processing conditions is the most promising alternative to chemical degumming.In the present study,using a wild ramie retting microbialflora collected from ramie planting gardened as a start population,a stable bacterial consortium was obtained by subculturing and domestication with ramie as the only carbon source and energy source.For this obtained retting microbial flora,the retting process was optimized and the degumming potential was evaluated.Three domain retting strains were isolated from the obtained stable consortium,for which the identification and degumming potential analysis were performed.(1)The fiber separating period for the domesticated consortium was about 3 days compared 5 days of the wild flora collected from ramie planting gardened.The effects of temperature,pH,rotation speed and bath ratio on the degumming rate and the activity of key degumming enzymes were investigated by single factor analysis combined with orthogonal analysis.Results show that the optimum fermentation conditions for the domesticated flora were as follows: pH 8,40?,bath ratio 1:15,the shaking speed 100 r/min.After 72 h degumming under such conditions,69.2% ramie gums were removed,and the resulted fiber can met the spinning requirement.And the quality of the resulted fiber was also characterized by SEM,XRD and FT-IR.(2)Using streaked plate method and Congo red hydrolysis circle staining method,seven dominant degummingstrains designated as G1,G2,M1,M2,X1,X2,and X3 were screened out from the domesticated flora.And 3 trains M1,G1,and G2 were finally confirmed and selected by enzyme activity test and were identified as Bacillus subtilis,Paenibacillus macerans and Bacillus cereus strain,respectively.For M1,the laccase activity was tested to be 0.65 U/mL and can be effect utilized for ramie degumming by “two-stage method”.(3)For the three strains selected,the degumming process was optimized and the degumming potential was evaluated.The optimal degumming conditions for G1 was pH 7,40°C,bath ratio1:15,speed 150 rpm;for M1 was pH 8,40°C,bath ratio 1:15,speed 50 rpm;for G2 was pH 6,40°C,the bath ratio1:15,rotation speed 100 rpm.(4)Multiple strains combined degumming was studied by three-srain combination and tow-strain combination,and G1-G2-M1 was the better conbination.The ramie degumming experiment was conducted under the conditions of temperature 40°C,pH8,bath ratio of 1:15,100 rpm,and inoculation amount of 10%.After 84 hours of degumming,66.1% ramie gums were removed.