Isolation,Screening And Application Of Excellent Acetic Acid Bacteria

Acetic acid bacteria(AAB)are very important industrial microorganisms.It can ferment ethanol to produce acetic acid,which was widely used in the production of vinegar and related products.Moreover,some AAB can produce pigments and bacterial cellulose that have a wide range of applications.In the present study,the isolates were isolated from Shangri-La barley vinegar,and the highly acetic acid yielded bacteria were screened.Then,the acetic acid production characteristics of three isolates with higher acetic acid yield were studied,and the best isolate of them was used in Panax notoginseng honey vinegar producing.In addition,the bacterial cellulose membrane production of 10 isolates with high acid and cellulose production were studied.And the medium for the bacterial cellulose producing were optimized.The main results are as follows:1.In total,37 bacterial strains were isolated from Shangri-La barley vinegar,and 30 of them were proved to be acetic acid bacteria.From them,13 highly acid-producing isolates were screened,and were identified to be Komagataeibacter.Then,three isolates(G-6,G-8,G-11)were found to be able to produce more acetic acid than the others,and the acid production rate of them were G-11>G-6>G-8.However,the yield of them were G-6>G-8>G-11.Further study indicated that the optimum acid production condition of them were: initial ethanol and acid concentration is 6% and2 %,respectively,and the fermentation temperature is 30 ?.G-6 was chosen for Panax notoginseng honey vinegar production for its better acid production rate and the yield.2.The Panax notoginseng honey vinegar production condition was optimized by single factor experiment as followers: 5 %-7 % initial alcohol concentration,29 ?-31 ? fermentation temperature,8 %-12 % bacterial inoculation and p H 5-6.It was further optimized by orthogonal experiment as followers: 6 % initial alcohol concentration,10 % bacterial inoculation,p H 6,fermentation temperature 30 ? and10 days fermentation cycle,and the maximum acid yield is 47.9 g/L.The fermented Panax notoginseng honey vinegar is a new type of natural nutritive vinegar,which has special health care function of Panax notoginseng,honey and vinegar,rich in nutrition and good flavor.3.The water content of the membrane produced by each of the 10 bacterial cellulose-producing AAB was more than 95 %,and the highest water content membrane was produced by G-14(98.63 %).It was found that the yield,the flexibility and the elasticity of the cellulose produced by each isolate was better under the stationary culture when compared with the shaking culture.Among them,the highest yield was found in strain G-6.Further study indicated that the optimum media for G-6 producing cellulose was as follows: mannitol with the concentration of 3 %,yeast powder and beef powder in 1:1 ratio with the concentration of 2.5 %,triammonium citrate and disodium hydrogen phosphate with a concentration of 0.5 %,without organic acids and anhydrous ethanol.In addition,it was found that the nitrogen sources affect the yield of cellulose in G-6 very much.It arrives 14.94 g/L when adding 2.5 % yeast powder and beef powder to the medium.