The Studies On The Extract Process Of The Polyhydroxyalkanoates(PHA) From Halobacterium Sp XMQ19 Fermentation Broth

This text studied the PHA extract-craft from(Halobacterium sp) XMQ19 and the main physical and chemical characters of PHA.It contains:pretreatment experiment of fermentation,extraction experiment of PHA by organic-impregnant,directly extraction experiment of PHA from water solution,DSC and TGA test of PHA production.As follows are the main experiment results:1.PHA-product's biggest absorb wave-length is 234nm.The standard curve of UV absorb shows that nice linear relationship exist between sample concentration and PHA's UV absorb value.2.Flocculation and dilution can improve the cell recovery to 96.25%:dilute the fermentation solution to 1/2 times volume and adjust the pH to 8.0,then joined 0.2% ZnSO₄ into it,last centrifugate the fermentation under 4000r/min for 30min.3.Optimize the extraction craft by chloroform through orthogonal experiment.The best extract conditions by chloroform are 45℃,25ml solvent for 1g cell,90min.The recovery of PHA can achieve 89.34%at the purity of 98.56%and the molecular weight has 7.8×10⁵.4.Established a simple,economical and environmental extraction craft from water solution of PHA.It can keep the recovery of PHA above 75.64%at the purity of 94.66% and the molecular weight has 7.3×10⁵.The primary step of this craft is adjust the pH of the cell solution(37.5g cell/L) to 3.0 firstly,then joined 0.1%(w/v) detergent into it,and keep the temperature at 60℃,last centrifugate the cell solution under 4000r/min for 20min and ingather the deposition after stirring.The futher step is to wash the deposition by water to fixed volume(50.0g cell/L),then adjust the pH of the solution to 5.0,joined 0.15%SDS and 2.0%NaClO into it,keep the temperature at 40℃,last centrifugate the cell solution under 4000r/min for 20min and ingather the PHA after stirring.5.The result of DSC and TGA experiments shows nice character of machining.The melting point of PHA extracted through different crafts are both about 135℃,and the decompounding point are about 290℃also.