Lactic Acid Piece Aureus Un - 27 Embedding Immobilized And The Nature Of The Research

Pediococcus acidilactici could be produce y-aminobutyric acid (gamma-Aminobutyric acid, GABA), pediocin which been used as functional factors.The Pediococcus acidilactici UN-27which stored in the laboratory was immobilized with calcium alginate were studied in the paper. The embedding conditions were optimized by orthogonal test and response surface methodology. The properties of capsule were determined and its micro-structure was determined by using scanning electron microscopy, then semi-continuous fermentation were done to accumulat GABA by the fixed strains.At first, the preparation conditions of immobilized capsule with calcium alginate were optimized by single factor experiment, the major factors influenced the diameter, thickness and mechanical pressure of the capsule, CaCl2concentration, the concentration of sodium carboxymethyl cellulose (CMC), sodium alginate (SA) concentration, gel reaction time, hardening time, chitosan concentration and coating time. Therefore, on the basis of single factor experiments, significance factors affected the capsule mechanical pressure were selected by two-level experimental design. The significant factors were three:CMC, SA, and gel reaction time. the best conditions were obtained by using response surface analysis through three factors and three levels experimental:CMC concentration1.08%,0.66%of the SA, the concentration of the gel reaction time21.19min, the capsule optimized mechanical pressure is15.32N. Ultimately the optimum conditions of capsule prepared as follows:CaCl2concentration10.0%, the CMC concentration1.08%, SA concentration0.66%, gel reaction time21.19min, hardening time15min,0.4%chitosan coating time30min. Capsules made with the best conditions were scanned by electron microscope. Capsules inner surface was dense aperture, which can prevent the leakage of bacteria effectively, its outer surface was wrapped with a layer of chitosan which made it have compact structure, and can provide a good microenvironment that was a liquid microenvironment provied for the immobilized cells. The outer surface was apertures that nutrients and metabolites can flow free. The preliminary efficiencys of capsule were tested. The result showed the capsule with good storage stability, cell activity is still the original70.63%and has integrity structure through soaking15days; The capsule’s mechanical pressure didn’t changed with heating30min under30℃～80℃respectively.108cfu/mL Pediococcus acidilactici UN-27were entrapped. Through36h immobilized cell proliferation, the cell density was multituded from108cfu/g to1012cfu/g which precursor material was2.5g/L. The orthogonal experiments were done to obtain the optimum fermentation conditions that immobilized cells to produced GABA. That were incubation temperature of40℃; initial pH7.0;1.0%of the inoculum size;50%of the liquid volume. An average yield of GABA is6.29g/L through optimizing. Semi-continuous fermentation to accumlation GABA was done with immobilized cells, the first batch fermentation cycle time was three days, and2-17fermentation cycle time was2days. The total accumulation of GABA in semi-continuous fermentation during17fermentation cycle (35days) with immobilized cells is1.93times that of free cells.