| Mannitol is used extensive in several industrial areas,such as food industry,pharmaceutical industry,chemical industry,light industry.At present mannitol is produced commercially by natural extraction and catalytic hydrogenation methods.Microbial(LAB,Lactic Acid Bacteria)transformation for producing mannitol has many advantages,such as high reaction selectivity,mild reaction conditions,less sorbitol production and high yield.Lactobacillus parabuchneri fermentation to produce mannitol was mainly investigated in this paper.By studying the fermentation medium carbon source,nitrogen source,vitamin content,age of vaccination,inoculation quantity,pH,temperature,cultivation ways on the impact of transformation of mannitol,Also detected in the fermentation process(OD600)densities,produce acid quantity,fructose and glucose content changes,In the end,to optimize the culture medium and fermentation conditions(g/L):Glucose 50,fructose 50,corn steep liquor 20,K2HPO4 1.5,MgSO4 0.5,tween80 1,8 kinds of compound vitamins were greater than 1 mg,vaccination age 36 h,the inoculation volume of 20%,initial pH6.3 fermentation and fermentation temperature 30 C,anaerobic fermentation.The experimental results show that high concentration of sugar to the class brinell has inhibitory effect on the growth of lactobacillus,early growth slowly.Experiment with the method of fed-batch fermentation,total sugar 300 g/L(100 g/L glucose,fructose is 200 g/L)shorter fermentation time form 144 h to 120 h,mannitol concentration of 168 g/L,conversion rate was 93%,the volume production is:1.41 g/(L-h).With NaOH regulate pH,linkage flow and carbohydrate supplement,further shorten time to 96 h,eventually mannitol concentration of 172 g/L,conversion rate can reach.95%,volume production is:1.76 g/(L·h).For producing strains resistant to high concentrations of sugar,for 70 days,and the continuous culture of more than 1700 h of the strain resistance evolution.Sugar strains resistant,sugar in the early 300 g/L under the condition of fructose,growth rate increased significantly,the fermentation cycle is shortened from 168 h to 144 h,mannitol production increased from 180 g/L to 200 g/L.Through the study of chemical medium brinell lactobacillus,learned that Ala,Phe,Ser,Cys,Leu,Glu,Ile,Arg,Val is its essential amino acids.Growth factors must be as follows:B1,B2,B5,B6,NA,FA,Biotin.This paper further studies the fermented liquid filtration,concentration and crystallization process,one-time raw mannitol crystallization,mannitol purity reached 90%,the yield was 82%.Again after recrystallization can further improve the product purity,up to 99%. |
