A method for screening a nitrogen source suitable for the proliferation of lactobacilli
A technology for lactobacilli and nitrogen sources, which is applied in the field of screening nitrogen sources suitable for the proliferation of lactobacilli, can solve the problems of rapid screening of unfavorable nitrogen sources, large time and manpower, and cost, and achieve the effect of saving time and complicated operations
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[0047] (7) Preparation of seed liquid: inoculate the culture liquid of Lactobacillus (Lactobacillus casei CCFM711, Lactobacillus reuteri CCFM8631, Lactobacillus plantarum CCFM8661) activated once into the MRS liquid medium with an inoculation amount of 1-5%. The cells were activated and cultured in a constant temperature 37°C incubator for 18 hours. Then centrifuge to remove the supernatant, wash once with sterile physiological saline, add the same amount of normal saline as the culture medium to resuspend the bacteria, and use it as the seed solution for nitrogen source screening and cultivation.
[0048] (8) MRS medium composition: yeast powder 5g / L, anhydrous sodium acetate 5g / L, beef extract 10g / L, anhydrous glucose 20g / L, peptone 10g / L, magnesium sulfate heptahydrate 0.25g / L, phosphoric acid Dipotassium hydrogen 2g / L, manganese sulfate monohydrate 0.1g / L, diammonium hydrogen citrate 2g / L, Tween-80 1mL / L, adjust the pH to 6.0.
Embodiment 1
[0050] Embodiment 1: Nitrogen source screening of Lactobacillus casei CCFM711
[0051] (1) Traditional batch method for screening nitrogen sources
[0052] Medium preparation: 25g / L different nitrogen sources (yeast extract, yeast extract powder 803, yeast extract powder 528, yeast protein 103, soybean peptone, fish bone peptone, tryptone, fish peptone, beef peptone, bovine bone peptone, Beef extract powder, beef extract), replace all nitrogen sources (tryptone, yeast powder and beef extract) in the MRS medium respectively, and prepare medium with different nitrogen sources. Heat to dissolve, and sterilize at 115°C for 20 minutes.
[0053] Inoculate Lactobacillus casei CCFM711 seed solution with 2% inoculum, place it in an incubator at 37°C for static culture, and take samples to measure OD after the strain grows to the stable stage 600 . According to the results of batch culture of the strains, and using MRS as a control, a nitrogen source with a good effect on the prolife...
Embodiment 2
[0082] Nitrogen source screening of embodiment 2 Lactobacillus reuteri CCFM8631
[0083] The method is the same as in Example 1, except that the strain is replaced by Lactobacillus reuteri CCFM8631.
[0084] (1) Traditional methods for screening nitrogen sources
[0085] Table 4 Lactobacillus reuteri CCFM8631 traditional method screening results of nitrogen source
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[0087]
[0088] The results showed that the glucose content in the fermentation broth was all ≦0.92g / L at the end of the culture, indicating that almost all the glucose in the nitrogen source medium was fully utilized, and the pH value of some fermentation broths had dropped below 4.0 (Table 4); When the body grows to the stationary phase, it is due to the lack of carbon source or acid inhibition. The nitrogen source may not be fully utilized, and how much nitrogen source the bacteria have used to proliferate until the current bacterial concentration is unknown.
[0089] Moreover, when Lactobacill...
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