Microbial flocculant proteus vulgaris and application thereof in cane juice clarification

[0033] Example 1

[0034] Take 1 mL of activated sludge sample from a sewage treatment plant in Guangzhou and dilute it to 10 -1 ~10 -7 After different volume concentration gradients of , take 10 -4 , 10 -5 , 10 -6 , 10 -7 Sludge microorganisms were inoculated on agar medium by spread plate method. After inoculation, the cells were cultured in a constant temperature incubator at 30°C for 2 days, and a variety of microbial colonies were isolated on the plate medium. The colonies were picked by plate streak method and expanded in petri dishes. The above steps were repeated, and after 5 times of isolation and purification, microorganisms with different colony forms were obtained, which were inoculated on the slant medium and stored in a refrigerator at 4°C. The purified strains were then added to 50 ml of screening medium, and cultured in shake flasks at 35°C and 150 r/min for 3 days, and the flocculation activity of the obtained culture solution was preliminarily determined by the following method.

[0035] To 100ml of liquid containing 5g/L kaolin suspension, add 5ml of CaCl with a mass fraction of 1% 2 The solution was used as a coagulation aid, and then 2ml of microbial flocculant sample was added to adjust the pH value to 7.5. After stirring, let it stand for 5 minutes, and use a spectrophotometer to measure the absorbance of the supernatant at a wavelength of 550 nm. At the same time, distilled water was used instead of the sample to be tested. As a control, calculate the flocculation rate of the microbial flocculant sample to be tested: flocculation rate (%)=(A-B)/A×100%, A is the absorbance of the control supernatant at 550 nm, B is the sample supernatant at 550 nm Absorbance at 550 nm. Taking the strain with the flocculation rate over 80% as the target strain, re-screened to obtain a stable and highly active flocculant-producing strain. The microbial flocculant produced by the Proteus vulgaris N-25 has a remarkable flocculation effect on kaolin suspension, the flocculation rate is as high as 92.6%, the cohesion degree of the treated kaolin particles is improved, and the turbidity of the suspension is reduced.

[0036] The colony surface of the obtained strain was smooth and translucent, and expanded into a uniform thin layer on the surface of the nutrient agar, and the colony shape was straight rod. Its physiological and biochemical identification results are shown in Table 1, and the DNA sequencing results are shown in SEQ ID NO: 1. Through BLAST comparison, the homology with Proteus vulgaris is as high as 99.9%. The strain was identified as Proteus vulgaris by morphology, physiology and biochemistry and 16S rDNA gene sequence, and named as Proteus vulgaris N-25.

[0037] The microbial flocculant Proteus vulgaris N-25 obtained in this example has been deposited in the China Center for Type Culture Collection on November 5, 2014, and the serial number is CCTCC NO: M2014549. The preservation address is: Wuhan University Preservation Center, Bayi Road, Hongshan District, Wuhan City, Hubei Province, postal code: 430072.

[0038] Table 1 Physiological and biochemical identification of highly active flocculant-producing bacteria (+: positive; -, negative)

[0039]

[0040]

[0041] Example 2

[0042] The microbial flocculant Proteus vulgaris N-25 obtained by screening in Example 1 was inoculated into a test tube containing a seed culture solution and cultured at 30° C. for 24 hours. Then, it was inoculated into the fermentation medium for fermentation culture, the fermentation temperature was 35° C., the rotating speed of the shaking table was 150 rpm, and the fermentation time was 4 days. The fermentation broth was centrifuged at 6000 r/min for 30 min, and the supernatant was taken as a microbial flocculant.

[0043] Example 3

[0044] Take 100 ml of sugarcane mixed juice, add 50 μL of phosphoric acid with a mass fraction of 85%, adjust the pH to 6.8 with lime milk, heat and stir to 60° C. and keep for 2 min. Add 6% sulfur sulfite for fumigation, the amount of sulfur fumigation is 1.8g/L, then neutralize the pH to 7.1 with lime milk, heat to 100 ℃ for the second time, and quickly add 2ml of microbial flocculant or 0.1% polyacrylamide 0.2ml, stir well and let stand. The time required to settle 50 ml was recorded. After 30 minutes, measure the volume of the mud bottom, take the supernatant and filter it with a 0.45 μm microporous membrane, measure the optical conversion, refractive index and absorbance at 560 nm of the filtrate respectively, and calculate the simple purity and color value of the cane juice. Determination and calculation of purity and color value are carried out according to the method of "Analysis Method for Chemical Management of Sugarcane Sugar Production", and the results are as follows figure 1 shown. from figure 1 It can be seen from the microbial flocculant treatment of sugarcane juice, compared with polyacrylamide treatment, the sedimentation time is shortened by more than 6min, the final volume of mud bottom is compressed by more than 8ml, the purity of sugarcane juice is increased by more than 1.7%, and the decolorization rate is improved. more than 12.7%.