Screening and identification of efficient β- fructosyltransferase- producing Aspergillus oryzae and optimization of the fermentation condition

6 β- fructosyltransferase- producing Aspergillus oryzae strains were activated and cultured at shake flask fermentation.In this study,high efficiency liquid chromatography technology was applied to gauging the enzyme activity of β- fructosyltransferase,and the enzyme activity of β- fructosyltransferase produced by 6 different Aspergillus oryzae strains were contrasted,in order to screening the efficient β- fructosyltransferase- producing Aspergillus oryzae strains. Thus,experiments of single factor and orthogonal tests were done to optimize the fermentation condition.Experimental results showed that the influencing factors of fermentation were temperature,inoculum concentration,rotation rate,sucrose concentration,yeast extract concentration,initial p H and ammonia sulfate concentration. The optimum condition for higher β- fructosyltransferase were determined: cultured in the medium of 0.4%( m / v) sucrose,0.15%( m / v) yeast extract,0.2%( m / v) Na Cl,0.15%( m / v) ammonia sulfate,initial p H7.0,inoculum concentration 1.0% under 35 ℃,200 r / min in shake cultures for 96 h.Maximal β- fructosyltransferase activity of A- F04 was 519.65 U / g,increasing 11.45% enzyme activity compared with the original fermentation condition( 466.25 U / g).