Optimization Of The Production Processes For Enzymes By Aspergillus Niger Fermentation And Total Ferulic Acid By Enzymolysis Of Bran, And Antibacterial Activity Detection Of The Total Ferulic Acid

In order to improve the release of the total ferulic acid from bran and study its antibacterial effect,firstly,the strains with high yield of ferulic acid esterase,xylanase and cellulase were selected and their fermentation substrates were optimized,and then based on the single factor test,Box-Behnken test and response surface analysis were used to optimize the fermentation process of ferulic acid esterase,xylanase and cellulase from bran fermented by Aspergillus niger.Then,on the basis of single factor test of enzymatic hydrolysis of barn with mixed enzyme solution,the main influencing factors of enzymatic hydrolysis of barn with mixed enzyme solution were selected by using Plackett-Burman test,and then the hydrolysis process of self-made mixed enzyme solution were studied by Box-Behnken test and response surface analysis,so as to improve the release of the total ferulic acid in bran.Finally,the stability of total ferulic acid and its antibacterial activity against Escherichia coli and Staphylococcus aureus were analyzed.The results showed that:(1)Compared with other fungi,the mixed enzyme activity of ferulic esterase,xylanase and cellulase produced by Aspergillus Niger was the highest.The optimized conditions were as follows: bran 4.5 g,vinegar residue 0.5 g,distilled water 7.5 m L(water content about 60%),xylose 6.05 mg and yeast 6.90 mg(added amount 1.21%,1.38%,respectively),1.3×108 CFU/m L Aspergillus niger seed solution 0.49 m L(inoculation amount was 9.8%)and the fermentation time was 64 h at 30℃,ferulic acid esterase activity was the highest,16.63±0.32 U/g,under this condition,xylanase activity was3098.21±47.27 U/g,cellulase activity was 21.12±0.14 U/g.(2)The optimized process for ferulic acid production from bran by enzymatic hydrolysis with mixed enzyme solution were as follows: Ca Cl2 addition was 5.0 mmol/L,p H value was 4.5,solid-liquid ratio was 1:30.5,hydrolysis time was 120 min at48℃.The release amounts of the total ferulic acid of bran reached the highest 5.41±0.03 mg/g.(3)The stability of the total ferulic acid was affected by temperature,storage time and light.With the increase of temperature,the stability of ferulic acid was gradually decreased.The total ferulic acid was easy to decompose in incandescent light,and the higher the intensity of the light,the faster the decomposition.(4)The results of antibacterial test of the total ferulic acid showed that the minimum inhibitory concentration of the total ferulic acid against Escherichia coli was 0.6 mg/m L,the minimum bactericidal concentration was 2.4 mg/m L;the minimum inhibitory concentration of the total ferulic acid against Staphylococcus aureus was 0.3 mg/m L,the minimum bactericidal concentration was 1.2 mg/m L.In conclusion,the fermentation of bran by Aspergillus niger could produce ferulic acid esterase,xylanase and cellulase,and the mixture of these three enzymes could produce antibacterial active substance ferulic acid and its stability was affected by light,temperature and storage time.This study provides a data reference for the research and development of bran for anti-feed.