Ox Bone Peptone Peptide Distribution And Industrial Fermentation

Peptone is the main nutrient nitrogen for microbial growth which is the mixture composed with protein, peptone, peptide, amino acid. In national standard, the quality criterion of peptone products is formulated as the content of ammonia nitrogen and total nitrogen . But little has been done about the length distribution of peptide chain in peptone with different hydrolysis degree and about the influence to microorgamism cultured by peptone as nitrogen source .In this paper, the peptones from bovine bone were obtained by enzyme hydrolysis, also the distribution of peptide fragments and its influence on microbial growth and fermentation were studied. The research could be a basis to make better usage of peptone as a microbial nutrient nitrogen source for fermentation.The bone protein was hydrolyzed separately by bone protease and flavor enzyme and double enzyme (bone protease and flavor enzyme ) and the hydrolysis conditions were optimized. The results showed that the optimal condition were (1)Bone protease: enzyme addition of 0.2%, pH9.5, at 55℃, reaction time 2h; (2)Flavor enzyme: enzyme addition of 0.05%, pH7.5, at 55℃, reaction time 2h;(3)Double enzyme : add ratio (bone protease: flavor enzymes) 4:1, pH9.5, at 55℃, reaction time 2h.On the basis of hydrolysis optimization, 11 types of peptone were obtained according to the differences of Enzymes and ammonia nitrogen values ,which were named respectively bone protease G0.5,G2,G6,G10, flavor enzyme F2,F6,F10, and Double enzyme D0.5,D2,D8,D10. These peptones were experimental material to study polypeptide distribution of bone peptone and its influence of fermentation.The free amino acids and peptide distribution of 11 types of peptone were analyzed in order to further investigate the degree of peptone hydrolysis. The results obtained by automatic amino acid analyzer showed that there were free amino acid at the percent of 0.8-1 in peptones hydrolyzed by Flavor enzyme, about 3.52-6.74% in peptones by bone protease and 3.81-6.98% free amino acid in peptone hydrolyzed by double enzymes. The content of free amino acids increased in the peptones with higher ammonia nitrogen.Gel chromatography were used to separate peptides of different length. In consider of dispersion distribution of peptide fragments, Three kinds of gel with different seperation range of molecular weight were selected, they were Sephadex G-100, G-50 and G-25. After enzyme hydrolysis, the peptide content of macromolecular was reduced, while the level of small molecular peptides was increased. The hydrolysis effect was obvious for hydrolysis of bone protease and doublel enzymes, at most 66.07% of macromolecule peptides were hydrolyzed into small fragments which concentrated at 5-30Kda, reached to 42.17%. The peptones with higher ammonia nitrogen were detected to be with higher proportion of small molecule peptides. Compared to bone protein before hydrolysis, only a little part of macromolecular peptide were hydrolyzed by flavor enzyme ,just like revealed by low content of ammonia nitrogenTwo strains of bacteria were cultured in order to analyze how the 11 types of peptone influence the growth and fermentation of bacteria. The culture of Lactobacillus paracasei showed that distribution of the peptides in different peptone had little effect on the growth and fermentation. Different peptones had a certain influence on the fermentation of protease-producing bacteria W7, The peptone with small peptides could be used more efficiently by bacteria W7 and created protease with higher enzyme activity. Peptone D10 by double enzyme hydrolysis got the highest protease activity ,reached to 107.53U/mL.