Oil Removing of Waste Silk by a Process of Combining Bacteria with Surfactants

The removing of oil from waste silk is carried out widely by microbial fermentation. However, it is difficult to remove the oil completely. In this study, surfactants were used to enhance microbial oil removing. In seven of the surfactants that were tested, 0.1% of the anionic surfactants inhibited the growth of bacteria and 0.1% of the nonionic surfactants partially inhibited the growth of bacteria. When only the surfactant was used to remove oil, all of the tested surfactants helped remove oil from the waste silk and treatment that added 0.1% AEO-9 gave the lowest oil content.When surfactants were combined with bacteria to remove oil, the oil content was further reduced and the lowest oil content was obtained by combining AEO-9 and bacteria. The optimum conditions for oil removing by combining AEO-9 with bacteria were pH8.0, temperature 40°C, 4% (v/v) inoculum size and 3 days incubation time. Compared with untreated silk, silk treated by combining surfactants with bacteria resulted in a decrease in oil content and improvement in appearance. Scanning electron micrographs showed that treated samples had a clean surface.