The Study Of Glycinin Basic Antibacterial Peptide Concentration And Antibacterial Property And Its Application Effect

In this study, glycinin basic antibacterial peptide (GBAP) was isolated and extracted through the method of isoelectric precipitation from defatted soybean meal. Sephadex G-50 column chromatography was used for the purification of GBAP. Then microbial membrane adsorption method was used to concentrate GBAP. The effect of GBAP on antibacterial activity, membrane permeability and morphological changes of Escherichia coli (E. coli) were investigated. Besides, the effect of GBAP on sensory properties and physicochemical indexes of chilled meat were researched. The main experimental results were as follows:(1) According to the method of isoelectric precipitation, glycinin was isolated and extracted from defatted soybean meal. Then disulfide bends between acidic and basic peptide was cut off using β-mercaptoethanol before two kinds of peptides were isolated according to the difference of isoelectric point of the peptides. GBAP was purified by Sephadex G-50 column chromatography, and the purity of 80% of GBAP was obtained. Microbial membrane adsorption method was used to get GBAP with the purity more than 95%, which showed that this method can be good to concentrate GBAP.(2) Minimal inhibitory concentration against E. coli was evaluated by Oxford cup method and spectrophotometric method, respectively. The dynamics study of GBAP against E. coli was investigated by the colony-counting method. The results showed that the minimal inhibitory concentration of GBAP was 400μg/ml. The antibacterial activity of GBAP against E. coli was increased with the increase of concentration.(3) To reveal the effect of GBAP on membrane permeability of E. coli treated with GBAP, crystal violet experiment, conductivity analysis and ion leakage analysis were performed. Through the crystal violet experiment, the value of OD590 increased with the increase of GBAP concentration. Through the conductivity analysis and ion leakage analysis, the value of conductivity and ion leakage increased with the increase of time, showing that GBAP can change cell membrane permeability. Atomic force microscope was used to observe the morphological changes of E. coli cells treated with GBAP. The photomicrographs showed that GBAP caused distinct changes in the cell envelope morphology and resulted in the formation of grooves and pore-like lesins as well as the collapse of the cell structure, as demonstrated by atomic force microscope.(4) In the research of the effect of GBAP on sensory properties (color, odor and texture) of chilled meat, compared with the control group, time of maintaining of well sensory properties of chilled meat was increased with the increase of GBAP concentration. AN OVA demonstrated that 0.16% and 0.2% GBAP can maintain good sensory properties of chilled meat for a long time, and 0.2% GBAP can better keep the good sensory properties of chilled meat for 8 days.(5) In the research of the effect of GBAP on physicochemical indexes of chilled meat, GBAP had a significantly impact on microbiological indicator (TBC) and physicochemical indexes (pH, TVB-N, and MetMb) with the increase of concentration of GBAP when compared to control. However, GBAP had no effect on TBA of chilled meat. These results revealed that 0.16% and 0.2% GBAP could significantly inhibit the growth and reproduction of microorganisms, and decrease the decomposition of meat proteins, and delay the change of color of chilled meat. Therefore, GBAP had the potential to be a nature preservative and to extend the shelf life of chilled meat.