Isolation Of Xylanase Producing Bacteria From The Large Intestine Of Adult Inner Mongolia Black Sow And Its Enzyme Producing Factors

Second only to cellulose in natural abundance, xylan is a major component of hemicellulose fraction of the plant cell walls. Xylanolytic enzymes, a system of hydrolytic enzymes, act cooperatively to convert xylan into its constituent sugars. Among these, xylanase (endo-(3-1,4-D-xylanase) [EC3.2.1.8] plays a crucial role and has great potential applications in pulp and paper industry, food industry and feed industry etc. Xylanases have wide commercial applications in industrial processes, such as the feed industry, the food, the paper and pulp industry, and weave industry.The aim of this experiment is that we sceen a high-xylanase producing bacterium,reaserching the optimization of xylanase production conditions and characterization of xylanase.This thesis was described in the following two sections.1. It is based on the oligoses produced by the xylanases breaking down xylan substrates, lots of transparent circle will be formed around the bacterium, a bacteria strain Zlf was isolated from adult sow large intestines. It was preliminary identified as Bacillus. According to the common dye, Gram staining, its morphology characters.2. Researching in the optimization living conditions of Zlf and enzyme characterization producing by strain Zlf, the results showed:The best condition for strain Zlf producing xylanase was oat xylan used as carbon, peptone as nitrogen source, fermentation time 60h and initial pH6.0 temperature 38℃.The further research was performed on the properties of xylanase, we got through changed temperature and pH values when xylanase reacted with the relevant substrate, in order to determine the optimal reaction temperature and pH optimal, The activities of the crude enzymes were measured at different temperature and various pH, The results demonstrated that the optimal temperature of xylanase is at 50℃. The bacteria strain Zlf belonged to midtemperature-resistant enzymatic classify, however, when it existed in a high temperature, enzymatic activities dropped dramatically. The optimal pH is at 6, and the xylanase remained higher activity over a range of pH 5 to 8. Compared with other reports about xylanases, the xylanase produced by strain Zlf has some advantages on alkaline resistance.In the metal ions investigated, when concentration was 1 mmol/L, Fe2+ promoted effects on xylanase, Fe3+ inhabited its activity, other ions had no transparent effects.When concentration was 5 mmol/L, Cu2+ inhabited almost all the activity,other ions all inhabited its activity more or less.