Font Size: a A A

Studies On The Production, Purification And Characterization Of β-mannanase From Bacillus Subtilis WD23

Posted on:2010-08-03Degree:MasterType:Thesis
Country:ChinaCandidate:B B XiangFull Text:PDF
GTID:2121360275466803Subject:Microbiology
Abstract/Summary:PDF Full Text Request
β-mannanase which is a kind of endo-hydrolases,belonging to hemiccllulases could catalyze the hydrolysis of theβ-I,4-D-glycosidic linkages,which had been found applications in food,medicine,papermaking,textile printing,petroleum extraction and biological technology and so on.Theβ-mannanase producing bacterial strains was found from the microbe laboratory of Northeast Forestry University,which was been defined Bacillus subtilis and was named as Bacillus subtilis WD23.The main research contents of this thesis include the following: optimizing the culture conditions of the fermentation,purifying theβ-manannase produced by Bacillus subtilis WD23,finding out the main characterizations of the purifted enzyme and degradation on guar gum and modified guar gum.The results showed that:(1) The fermentation conditions of the Bacillus subtilis WD23 were optimized accordin g to single factor and orthogonal tests.The results showed that the strain grew best wi th 3%konjac powder as carbon,1%beef extract and 1%NH4H2PO4 as nitrogen source, pH 9.0,temperature 37℃,100mL medium per 250mL flask,incolumn volume for the striain was 1%,180r/min.After 12 hours cultured,the strain could show the highestβ-mannanase activity as 2451U/mL which is 5.8 times compared with optimizing before.(2)β-mannanase from Bacillus subtilis WD23 was purified using DEAE-Sepharose FF anion-exchange chromatography and Sephadex G-75 gel filtration.The purification fold was 14.1 and recovery of total laccase activity was 20.7%.The molecular weight of the purified enzyme was about 40 kDa after the electrophoresis of SDS-PAGE.(3) The enzyme was sensitive to the temperature and pH,and the optimized pH was 5.6, which was bitable at pH 5.0-7.0,and the maximum enzyme activity existed at 55℃which was bitable below 55C(150min).The activity of the enzyme was stimulated by Ca2+,Mg2+,Ba2+, Co2+,Zn2+ and K+,but inhibited by Na+,NH4+ and Li+.When the substrate ofβ-mannanase is konjac glucomannan gum,the Km and the Vm are 0.11mg/mL and 52.9μg/min·mL,respectively. When the substrate ofβ-mannanase is locust bean gum,the Km and the Vm are 2.33mg/mL and 1666.7μg/min·mL,respectively.When the substrate ofβ-mannanase is guar gum,the Km and the Vm are 2.8mg/mL and 2000μg/min·mL,so that theβ-mannanase from Bacillus subtilis WD23 have the best reaction with konjac glucomannan gum.(4) Guar gum and modified guar gum with 0.65%concentration could be decompounded byβ-mannanase from our strain,whose degradation rate is 14 times by the pure enzyme than by the crude enzyme.The guar gum could be broken down with the pure enzyme in 20 minutes, which viscosity was from 1852.9mPa·s to below 20m Pa·s,and the modified guar gum could be broken down with the pure enzyme in 20 minutes,which viscosity was from 472mPa·s to below 20mPa·s.Therefore applications ofβ-mannanase from our strain in oil drilling have greater potential significance.
Keywords/Search Tags:β-mannase, Bacillus subtilis, fermentation, purification, characterization of the enzyme
PDF Full Text Request
Related items