Solid-state Fermentation Of Sheep Gastric Contents To Produce Xylanase By Bacillus Subtilis S-211

The paper studied respectively from the medium components,inorganic salts, inoculum,cultivation time,cultivation temperature and initial pH on the single factor solid-state fermentation of laboratory preservation Bacillus subtilis S-211 producing exocellular xylanase by sheep gastric contents and optimized by orthogonal experimental design.The results showed that the best optimized culture medium of solid-state fermentation by Bacillus subtilis S-211 were(adding 10g culture medium in 100mL triangle flask) sheep gastric contents/corn flour/cake flour/wheat bran50: 12:19:19,Mn²⁺0.6g/L,Na⁺7g/L,Mg²⁺5g/L,K⁺14g/L,Fe²⁺0.3g/L,Ca²⁺6g/L,Zn²⁺0.5g/L.The optimal laboratory fermentation conditions were initial pH7.0,inoculation 4mL(adding 4mL of concentration of 10⁷cfu/mL spore suspension in each 100mL triangle flask), fermentation temperature 30℃,fermentation time 36h.The optimized xylanase production reached 1219.628U/mL,increased 1.8 times more than normal culture.The experimental study provided a reliable theoretical basis for enlarging solid-state fermentation conditions of sheep gastric contents to produce xylanase by Bacillus subtilis S-211.Followed the optimal fermentation conditions to culture Bacillus Subtilis S-211 for receiving crude xylanase.The crude xylanase was isolated and purified by means of 20%-80% ammonium sulfate precipitation followed by chromatography on SephadexG-25 and SephadexG-100.The purification multiples of the xylanase were 5.28,the source enzyme with an activity recovery of 30.98% and specific activity of 14.58IU/mg.SDS-PAGE showed a single electrophoretic band and its molecular weight was 37.8kD.Studied the properties of xylanase producing by Bacillus Subtilis S-211,the results showed that the optimum temperature of was xylanase was 55℃,among 25℃-50℃,the xylanase was stabile;The optimum pH was pH 6.0,among pH4.0-pH8.6,the xylanase was stabile;The xylanase could be inhibited by Pb²⁺,Fe³⁺,Hg²⁺ and activated by Mg²⁺,Zn²⁺,Fe²⁺,K⁺.Its Km for Xylose at 55℃and pH6.0 was 5.202mg?mL and Vmax was 0.243mg/(min·mL).