The Optimization Of Fermentation Conditions And The Preliminary Analysis Of Synthetic Mechanism

Poly malic acid(PMLA)is a biopolymer with good biocompatibility,biodegradability and biological absorption capacity.It is considered to be a potential food packaging material and now is widely used as a drug carrier,biomedical material,water absorbent material,cosmetic product and microbial DNA polymerase Inhibitor.The application prospect is very wide.In this paper,Main results were listed as follows.The effects of amino acids on PMLA and optimization of the culture mediumTo research the influence of amino acids to PMLA,a shake-flask test was conducted and I found Aureobasidium pullulans CGMCC3337 would grow better on the medium with aspartic acid,leucine,valine and threonine,which had positive effects on promoting PMLA yield and PMLA molecular weight.Through the orthogonal experiment,the fermentation medium of A.pullulans CGMCC3337 was optimized with a assessment criteria of PMLA yield and its molecular weight.Then the results showed that after optimization,PMLA flask production and the PMLA molecular weight were increased by 40.92%and 45.20%,respectively.Optimization of process parameters in 5 L fermentation reactorFermentation experiments carried out in 5 L fermenter demonstrated that fermentation temperature,agitation rate and ventilation would have significant effects on microorganism growth,PMLA yield and PMLA molecular weight.The fermentation process have three phases of the early phase,the logarithmic phase and the stable phase,and we could control the fermentation conditions for different phases.The fermentation conditions of different stages should be controlled,separately.Finally,under a constant rotation speed of 400 r/min,and a flow rate of 1:1.2,the fermentation temperature should be adjusted to 30? during 0-24 h and after 24 h adjust the fermentation temperature to 25?.Under optimal conditions,after 144 h cultivation,the PMLA concentration reached to 44.9 g/L and the PMLA molecular weight reached to 8512 Da.Preliminary study on ATP synthase subunit alpha and ATP synthase subunit betaPreliminary analysis the gene of ATP synthase subunit alpha and ATP synthase subunit beta,and their protein three-dimensional structure were predicted.Therefore,the conclusions above provided the theoretical and technical support for rebuilding the Aureobasidium pullulans and a certain guiding significance for the construction of genetically engineered microorganism.