Enrichment Breeding For High Osmosis Tolerance And Process Research For Mannitol Production Of Lactobacillus Parabuchneri

Mannitol is a kind of functional sugar alcohol,which is widely used in medicine,food,light industry,chemical industry,etc.There are various methods for mannitol production.Microbial reforming process for mannitol production has been widely concerned and will change the mannitol production industry pattern in the future due to its high selectivity,mild reaction conditions,no by-products sorbitol,high yield,etc,Therefore,it is important to screen a mannitol high-yield strain and to study its fermentation process.In this paper,mannitol preparation under anaerobic fermentation with Lactobacillus parabuchneri has been studied including the influence of carbon source,nitrogen source,vitamin,acid neutralization agent.The results showed that there is no obvious difference on the L.parabuchneri K1 strain growth and mannitol production when total sugar concentration is lower than 240 g/L whatever the carbon source is sole fructose,or mixed sugar with glucose and fructose ratio of 1:2.The production of mannitol,acetic acid and lactic acid concentration is close to theoretical values.The essential amino acids for K1 strain is Ala,Phe,Ser,Cys,Leu,Glu,Ile,Arg,Val,Met,Trp,Thr and the essential vitamin is B1,B2,B5,B6,NA,Fa,Biotin.There is no obvious influence on L.parabuchneri K1 strain growth when adding a small amount of glycerol in the medium.The K1 strain can produce mannitol even if high concentration(12-18%)mannitol exists in the medium.Calcium carbonate can be used as acid neutralizer in the process of fermentation.In order to get rapid and efficient mannitol-producing strain,enrichment of high permeability resistance breeding was applied and got a L.parabuchneri K2 strain.The results showed that K2 strain growth,substrate utilization and product generation are much better than K1 strain.In the condition of 2L fermenter and 300 g/L fructose,fructose utilization rate of the mutant was increased by 103%,and the fermentation period was shortened by 46.4% comparing with the K1 strain.The mannitol yield was reached to 190 g/L,which was 94% of theoretical conversion.The mannitol crystallization process has explored with fermented broth.The best crystallization process for high purity and yield of mannitol is decoloring 2 h with 4% active carbon,decompression filtration,70℃ concentration at pH4.0,gradient cooling crystallization,three times concentration crystal.The mannitol purity can reach more than 96%,and the mannitol yield can reach 81% with the above process.In order to clean production,the crystallized liquid was treated with other bacteria.The results showed that the lactic acid in the crystallized liquid can be used by Propionibacterium shermanii to produce acetic acid and propionic acid.The mannitol and lactic acid in the crystallized liquid can be used by Propionibacterium acidipropionici to produce acetic acid and propionic acid.The growth of Propionibacterium acidipropionici was inhibited under high concentration of crystallized liquid.Mannitol and a small amount of acetic acid in the crystallized liquid can be used by Glutamate corynebacterium for its growth and to produce a small amount of pyruvic acid.Organic substances in the crystallized liquid can be used by G and T yeast.