Monday, May 5, 2008
9-23

Development of Efficient Purification Process for Poly(γ-glutamic acid) from  Newly Isolated Bacillus sp. RKY3.

Jae-Hoon Jeong1, Jin-Nam Kim1, Young-Jung Wee2, and Hwa-Won Ryu2. (1) Higher Education Center for Bioregulator Research, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, South Korea, (2) School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, South Korea

Recently, there has been an increasing interest in the development of biopolymer materials, such as polylactic acid, poly-3-hydroxybutyrate, bacterial cellulose, and poly(γ-glutamic acid) (γ-PGA). It is necessary for pretreatment to separate cells, because the viscosity of γ-PGA culture broth is very high. Therefore, to separate the γ-PGA from culture broth, the cells should be separated from culture broth prior to γ-PGA purification.

We studied influence of various pHs and dilutions on viscosity of culture broth, and studied the effect of solvent for separation of γ-PGA from cell free-culture broth. Furthermore, the more effective and economical purification procedure of γ-PGA from cell free-culture broth was investigated with ultra filtration system. The completed removal of cell was achieved with dilution of 7.5, 5, and 2.5 fold at pH 6, 4, and 2, respectively. In the study about proportion of culture broth and ethanol for separation of γ-PGA from broth, the maximal recovery was accomplished in the proportion of 1 to 5 at pH 6. In experiment of U/F system, the γ-PGA with less 100 kDa of molecular weight was separated with water, so that γ-PGA with more 100 kDa of molecular weight was concentrated.


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