The Production Optimization And Structure Analysis Of EPS That Produced By Lactobacillus Kefiranofa Ciens ZW3

The study on EPS that produced by lactic acid bacteria has become a hotspot. It is generally recognized as safe, green, and has played an important role on water holding capacity, texture and taste of fermented foods. Furthermore, the physiological functions of EPS that are produced by lactic acid bacteria are obvious.Those functions include cholesterol-lowering, anti-allergic, antineo-plastic, antibacterial, anti-inflammatory, regulation of immune and so on. The EPS produced by lactic acid bacteria has become one of hot research topics in the study of the industrial microorganisms.Firstly, we determined the optimum medium and conditions:glucose1.6%, lactose0.4%, yeast powder4.5%, dipotassium phosphate0.18%, manganese sulfate0.02%, sodium chloride0.01%, cysteine hydrochloride0.1%, sodium acetate1.5%, Tween-800.1%, initial pH6.2, inoculation quantity was3.0%. Cultivation methods:anaerobic and stationary cultivation at30℃, fermentation time was84h.Then, the EPS that was produced by modified medium was extracted and purified. The protein in EPS was deproteinization by TCA method and purified by chromatographic column of Q-Sepharose Fast Flow and Sepharose CL-4B. Full wavelength scanning and HPLC were used to identify its purity identification. The purity of the purified EPS was93.1%.At last, the structure of EPS was analyzed after purification. And we compared the difference between the EPS produced by modified medium and whey medium respectively. Gas chromatography mass spectrometry results showed that both kinds of EPS contain three kinds of monosaccharide components, they are glucose, galactose and mannose, but the proportions of every component had a really large difference. Malaprade reaction and Simth degrade results showed that the EPS mainly contain1â†'2connection, also contain a small amount of1â†'6,1â†'4and1â†'3connection. The FT-IR results showed that both EPS are pyranose carbohydrates.The AMF result showed that the EPS are granular.Two kinds of EPS surface microstructures had great difference. SEM showed the former surface took a shape of thin slice, and the surface are folding; While the latter has a typical alveolate structure, it formed the network structure, and seen at2000x there are some larger cavity.