Enzyme Production Capacity Of Bacillus Licheniformis And Bacillus Subtilis And Its Application In The Fermentation Of Moringa Oleifera Leaves

Moringa oleifera is a high-yielding woody forage tree species which is native to India.It is rich in nutrients and exhibit high-efficient biological activity.However,Moringa oleifera has more anti-nutritional factors,so that it is difficult to be directly absorbed and utilized,and the palatability is also relatively poor.Microbial fermentation technology can effectively improve the nutritional level and palatability of Moringa oleifera.Improving the enzyme production ability by optimizing the culture conditions of microbial strains is one of the ways to improve the effect of feed fermentation.In this work,the enzyme activities of the fermentation fluids of two Bacillus strains cultured in different conditions were analyzed.The results show that the optimized culture conditions of Bacillus licheniform and Bacillus subtilis are inoculated 2 % seeds in the medium which contain 1.5 % nitrogen source and 1 % Na Cl and cultured for 32 h.The cellulase activity of Bacillus licheniformis fermentation fluids is about 12 U/m L,the protease activity is 29.069 U/m L and the amylase activity is 57.588 U/m L.The cellulase activity of Bacillus subtilis fermentation fluids is 12.520 U/m L,the protease activity is 87.185 U/m L,and the amylaseactivity is 685.129 U/m L.In order to further study the effect of strain culture conditions on the metabolic pathway of the strain,Bacillus subtilis was cultured with 0 %,1 % and 3 % Na Cl,and determined the GC-MS metabolism group of different salinity culture strains.From the result of metabolomics analysis based on GC-MS,11,41 and 35 metabolites are detected from the 0 %,1 % and 3 % salinity groups respectively.From the KEGG database,it is found that the metabolites identified under three different salinity,the metatolities are involved in carbohydrate metabolism,amino acid metabolism,nucleotide metabolism and lipidmetabolism pathway.What's more,the metabolites from 1 % salinity groups also participate in the process of energy metabolism.Two strains are used to ferment the Moringa oleifera leaves.The results show that after fermentation by Bacillus licheniformis,the content of soluble protein increase by 76.6% and the content of reducing sugar increase by 16 times after fermentation.After fermentation with Bacillus subtilis,the content of soluble protein and reducing sugar increase by 92.7 % and 3times.The content of cellulose decrease by 14.38 %,and the content of 10 amino acids increase in 16 kinds of free amino acids.The valine,isoleucine,leucine,phenylalanine and lysine of essential amino acids increase 5.88 %,5.13 %,12.90 %,12.12 % and 10.63 %,and threonine content decreases by 2.56%.This study provide theoretical basis for improving the enzyme production performance by improving the culture conditions of the strains,and provide reference data for the application of these two Bacillus to Moringa oleifera fermentation.