Screening And Identification Of Waste Silk Degreasing Bacteria And Studying On Degreasing Technology By Bacteria

Today chemical fibre have been developed very well, however spun-silk product is still popular in the world because its soft, light, perfect luster, hygroscopic and comfortable dressing. Waste silk has many impurities which including sericin and grease, these impurities should be removed before spinning, this procedure is called refining. During the refining, degreasing is quite difficult. Schapping is a natural fermentation process, which is often used to remove oil from material. This old method is very effective on degreasing and has low investment, but it has many disadvantages, such as much area needed, long period, high intensity of force and bad smell. In this thesis, degreasing bacteria was isolated from the nature fermentation liquids and identified, and the greasing technology was searched.First oil-removing bacteria were isolated from natural fermentation liquid using double-layer medium, the species and amount of the bacteria were different in different fermentation liquid. Some bacteria had transparent zone on medium, and the others had no. The isolated bacteria was used to degrease, there wasn’t a good relativity between the degreasing efficiency and the activity of lipase produced. The strain X8 was selected due to its good degreasing ability.The strain X8 was identified based on its morphological, physiological and biochemical characteristic, The strain X8 belongs to Rhodococcus. The suitable condition for the growth of strain included 37℃, pH 7. The time of the exponential phase in LB medium is about 8 hours.The strain X8 was used to deal with waste silk, the effect of some factors on degreasing was evaluated, including the volume of inoculation, time, pH and temperature. The best conditions were got as following, 5g waste silk, the ratio of solid and liquid was 1:40, 1%bean cake, 200rpm, the volume of inoculation was 10%, fermentation time was 2 days, pH 7, 40℃. Bean cake could be used as the germ medium instead of LB medium.The degreasing process combining surfactant and fermentation was tested. The results showed that some surfactants inhibited the growth of the strain X8, some surfactants such as LAS, AES, AEO-9, Tx-10, Tween 20, Tween 80 and JFC had little influence on the growth of the strain X8. When the surfactant AEO-9 and X8 were combined to degrease, the residual oil content was low. The best technological parameters is listed as following: 0.1%Surfactant AEO-9, pH 7, 40℃, 3 days.