Investigation On Breeding And Dense Cultivation Of Lactobacillus Specific For Vegetable Fermentation

All of pickles, sour pickled cabbage,sauce, bean are a kind of public which have a long history to ferment vegetable ware, which creation craft can trace back to more than 2000 years ago. Vegetable fermented is enjoyed by more and more people in all countries with sour and fresh delicate fragrance, clearness of the pure and unadulterated, frailty is tasty and enjoy in retrospect long, get fed up with solving and open personal status and effect of the stomach. Ferment is as a kind of traditional health food which nourishment and health care effect of vegetable conduct cause people more and more of concern.The lactobacillus is to fermentvegetable production in of main production germ stub, sievingthe appropriation lactobacillus suited for the vegetable ferment is the key to shorten a vegetable to ferment production period, stabilize the product quality and raise the food safety. The key which raises a vegetable to ferment velocity, shortens to keep a hurl type pickles to ferment time and reduces to even keep second nitrate from producing is to raise the live bacteria number of compounds germ powders which is appropriatd to ferment vegetable. But dense cultivation is the key to prepare concentrated bacterial powder for vegetable fermentation.Main contents discussed in this thesis are as follows:(1) Three lactobacillus strains have been screened from the original culture fluid after certain time of vegetable fermentation. Characterization of morphology and physiochemical properties has confirmed that all of them are lactobacillus.(2) The study has been conducted to identify the fermenting capacity of these strains. After fermentation for 24 hours the fermenting solution of the strain (No.NCU0101) contains the biomass of 1.25×10⁹cfu/mL, with the acidity of 0.63 g lactic acid /100mL and pH 3.39.(3) The study of high cell density culture of lactobacillus No. NCU 0101 has shown that it is feasible to achieve the goal using buffer solution, chemical neutralization and feed batch culture. It is found that medium formula, culture conditions, and feed batch methods have great impacts on biomass growth. Suitable medium formulation is: 5% glucose, 1% peptone, 0.5%K₂HPO₄, 0.3%sodium acetate. Optimal culture conditions are pH 6.3～5.8, temperature 30℃, oscillation frequency 40 r/min , and culture time 20h. Appropriate feeding culture method is that 2.5% carbon and nitrogen sources (C/N ratio is 5:1) is added respectively after Oh, 4h and 8h. With the optimal culture conditions, the number of the bacteria cells is up to 7.83×10⁹cfu/mL.