Immobilization Of Bacillus Sbutilis In Silica-based Materials

Currently inosine production relies on the fermentation of free Bacillus subtilis, which is affected by factors scuh as short living time of bactrial, separation and purification of inosine from fermentation culture. These problems may be solved or improved by bioencapsulation.One of key issues in immobilizing cells is the support materials. Compared with organic carriers, silica-based materials have many advantages such as chemical stability and mechanical rigidity, low toxicity, strong ability of anti-microbial and controlled porous structure which is conducive to cell mass transformation, better biocompatibility, micro-environment of hydrophilic. Silica-based materials have been used by many reasrchers for enzyme and cells entrapment using sol-gel methods with TMOS and TEOS as silica sources. However, the major limitations are hydrolysis substances generated such as alcohol on enzyme and cells toxicity and poor hydrophilic. In this work, it has been investigated that sol-gel method and silica sources with two major classes, alkoxide and aqueous for bioencupsulating bacterial. Silica-based materials of organic modified TMOS, TEOS, sodium silicate solution entrapped Bacillus subtilis were prepared by alkoxide and aqueous silica sources. The effects of Bacillus subtilis encapsulation on inosine production were studied.TEOS silica gels with trace alcohol, better biocompatible DGS and doping silica gels, MSS, and MMS silica gels, double structure composite silica gels with TMOS and alginate calcium synthesis were synthesized by the silica sources of TMOS, TEOS. Materials structure was studied and inosine production Bacillus subtilis was encapsulated in synthesis silica gels. These silica-based materials are mesoporous material, some of which are microporous. They had more inosine yield than free Bacillus subtilis. The inosine yield of production inosine Bacillus subtilis entrapped in TMOS/ alginate calcium composite silica gels is 13.45g/L.Sodium silicate gels, H+ exchange sodium silicate solution gels containing trace Na+ and doping GLTES composite silica gels, nano silica powder and alginate sodium composite silica gels were prepared by silica sources of silicate sodium solution. Materials structure was studied and inosine production Bacillus subtilis was encap- sulated by synthesis silica gels, the interaction of material and cells was analysied, These silica-based materials are mesoporous material, its pore diameter range for 4-40nm, post-immobilition, the cells intact, the inosine production has increased, in particular, The inosine yield of production inosine Bacillus subtilis enclosed in the GLTES/H+ exchange sodium silicate solution composite silica gels is 14.91g/L.So, silica gels with bigger pore diameter, better biocompatible and hydrophilic, and more inosine production were prepared by aqueous silica sources precursor than the alkoxide.