# Alcaligenes sp.에 의한 Poly-$\beta$-Hydroxybutyric Acid의 축적

• 임명순 (부산대학교 자연과학대학미생물학과) ;
• 손홍주 (부산대학교 자연과학대학미생물학과) ;
• 박수민 (부산대학교 공과대학 섬유공학과) ;
• 이종근 (부산대학교 공과대학 섬유공학과) ;
• 이상준 (부산대학교 자연과학대학미생물학과)
• Published : 1992.08.01

#### Abstract

Microorganisms capable of accumulating poly-p-hydroxybutyric acid(PHB) were isolated from soil by enrichment culture technique. Among them, the strain designated as FL-027 had high PHB productivity and was identified as Alcaligenes. The optimal medium composition for cell growth was 8.0 $g/\ell$ of fructose and 3.0 $g/\ell$ of $(NH_4)_2S0_4$, equivalent to C/N ratio 5.04 at pH 7.0 and $30^{\circ}C$. To investigate the optimal conditions for the PHB accumulation, we divided the process into two stages; the first stage for the growth of the cell in nutrient-rich medium and the second stage for the PHB accumulation in nutrient-deficiency medium. The optimal conditions for PHB accumulation were 8.0 $g/\ell$ of fructose and 0.25 $g/\ell$ of $(NH_4)_2S0_4$, equivalent to C/N ratio 60 at pH 6.5 and $30^{\circ}C$. PHB accumulation was stimulated by deficiency of nutrients such as $NH_4^+$, $Ca^{2+}$, $SO_4^{2+}$ in medium. Among them. $NH_4^+$ deficiency was chosen because of its effectiveness. We found the inhibition of cell growth by fructose in batch culture. In order to keep the fructose concentration at an optimal level, intermittent feeding fed-batch culture was employed, and the cell concentration as high as 10.83 $g/\ell$ whose PHB content was responsible for 43% of the dry cell weight. The purified PHB was identified as homopolymer of 3-hydroxybutyric acid by using IR and $^1H-NMR$.