Study On High Density Cultivation Technics Of Halobacterium Sp XMQ19 Accumulating PHAs

In this paper,we study on high density fermentation of the Halobacterium sp accumulating PHAs.The content includes:selecting initial strains,improving culture medium and cultivation condition,fed-batch in flask and in fermentation kettle.Select the initial strains throw Nile Bule A accessed medium,and gain 8# strain as initial strains that the average CDW(cell dry weight) is 12g/L and the concentration of PHA is 3.96g/L,the productivity of PHA is 0.055g/L/h in flask.We can gain a perfect culture medium on the base of improvement test.The improved culture medium is:potato amylum 4%,NH₄Cl 0.2%,KCL 0.2%,MgSO₄.7H₂O 2%,yeast extract 0.4%,KH₂PO₄0.00375%,NaCl 16%,trace metal solution 0.5ml/L, pH7.0.and it can increase the CDW 19.6%,the concentration of PHA 3.5%compared with original culture medium.When seeds have been cultivated for 48h in flask and the percent of inoculation is 10%,then they can increase the CDW.500mL flask containing 80mL culture medium is the best.The pH of culture medium from 7.0 to 7.5 can accelerate the growth of this bacterium.The defoamer can accelerate the growth of cell,but the concentration can not exceed 4ml/L.The technique of fed-batch in flak is as follows.Initial culture medium is:potato amylum 1%,NH₄Cl0.05%,KCL 0.2%,MgSO₄.7H₂O 2%,yeast extract 0.05%,NaCl 16%, KH₂PO₄ 0.00375%.Fill potato amylum from 20h to 70h in 1ml/h velocity and NH₄Cl from 5h to 40h in 0.2ml/h velocity.Exponential fed-batch fermentation and fed-batch fermentation with intermitted culture medium addition both can increase CDW,but former suit the cultivation of this bacterium.In exponential fed-batch fermentation,the concentration of cell and PHA is 44.8g/L,19.8g/L,the productivity of cell and PHA is 0.503g/L.h,0.22g/L.h...