The Study On Screening And Fermentation Of 1,3-propanediol Producing Strain

1,3-propanediol(1,3-PD)is an important chemical raw material.As a potential intermediate product,it is widely used in fine chemicals,cosmetics,pharmaceutical and other industries.In addition,1,3-PD can be used as a monomer in the synthesis of various polyesters,urethane polymers,etc.In recent years,the rapid development of 1,3-propanediol is due to its important and irreplaceable role as a monomer in the synthesis of polyethylene terephthalate(PTT).In this paper,a strain with short growth period and high 1,3-PD yield was selected from the silt of Fenhe River to optimize the fermentation conditions,the influence of byproducts and the optimization of extraction conditions.To provide theoretical basis for industrialized production of 1,3-PD.The main results of this paper are as follows:1.Strain ZH-1 has the strongest ability of fermenting 1,3-PD among the 3 strains with glycerol as sole carbon source isolated from the sludge of Fenhe River in China.Further study on strain ZH-1 showed that it was gram negative bacteria,short rod,and the size was0.5-0.6×0.9-1.4μm.It was classified as a member of K.pneumoniae after the study of physiological,biochemical,phylogenetic(16S rDNA)and BLAST sequence alignment.2.The effects of initial glycerol concentration and fermentation time on the yield of1,3-PD were studied.The results showed that the optimum glycerol concentration was 50 g/L and the optimum fermentation time was 36 h.Single factor analysis and response surface optimization were carried out on 3 fermentation conditions of temperature,pH and inoculum concentration.The results showed that the optimal conditions were 36.33°C,7.73 and 10.53%.Under these conditions,the practical yield of 1,3-PD was 20.1658g/L.3.The effects of different concentrations of metabolic byproducts(ethanol,acetic acid,lactic acid and succinic acid)on 1,3-PD production and key enzyme activities werestudied.The results showed that the addition of a certain concentration of succinic acid could promote the production of 1,3-PD and increase the activity of 1,3-PD oxidoreductase(PDOR)and glycerol dehydratase(GDHt),and it had a little effect on the activity of glycerol dehydrogenase(GDH).However,the addition of ethanol,acetic acid and lactic acid to 1,3-PD production and the key enzyme activity have different degrees of inhibition.4.The effects of two methods of ultrafiltration-alcohol precipitation and aqueous two-phase extraction on the purification of 1,3-PD were compared according to the removal effect of protein and inorganic salts.The results show that the optimal purification method was ultrafiltration-alcohol precipitation method,in which methanol and ethanol are good alcohol sink.In addition,the removal of pigments by activated carbon,activated clay and diatomaceous earth was studied.The results showed that the removal efficiency of activated carbon was the best.Glycerol is a by-product of fermentation in the biodiesel production process,the use of glycerol fermentation production 1,3-PD has good economic and social benefits.Therefore,the use of glycerol fermentation to produce the 1,3-PD will be a development trend in the future.The purpose of this study was to provided theoretical basis and guidance for reduced the industrial production of 1,3-PD and reduced the costs and increased the yield.