ダウノマイシン発酵 : 鉄イオンの特異的生産増強効果と回収・精製法

抗腫瘍性抗生物質ダウノマイシンの発酵生産に対する鉄イオンの特異的な増強効果を明らかにするとともに、培養液からのダウノマイシンの回収・精製法を検討した。増強効果は、特に3価鉄イオンが有効で、およそ10mMの添加培養で無添加の4倍の生産力価(およそ300μg/ml)を達成した。関達するダウノマイシン前駆体D788-1発酵生産にはむしろ生産阻害的で、その効果はダウノマイシン発酵に特微的であった。ダウノマイシン培養液を水で3倍に希釈し、リン酸でpHを1.5として液層に酸抽出した後、合成吸着樹脂HP-20カラムに吸着させ、15～50%アセトンの直線濃度勾配溶出をおこない、ついでクロロホルム抽出処理により副成アナログ含有率2.0%以下の高純度ダウノマイシンを取得する方法を確立した。

The fermentation yield of antitumor anthracycline antibiotic daunomycin was found to be considerably increased by iron salts. The effect was more significaut with ferric ion than ferrous ion. When an optimum 10 mM of ferric sulfate was added to the culture, the daunomycin production was enhanced 4 folds as compared with that in the control culture without ferric sulfate. The iron effect was not observed with related anthracycline D788-1 fermentation. Recovery of intracellularly accumulated daunomycin to cultural filtrate was carried out by adding phosphoric acid to 3-fold fermentation broth to acidify to pH 1.5 and stirring 2 hours. The filtrate was then applied to HP-20 resin column, which was eluted with a linear gradient from 15 % to 50 % acetone. Daunomycin was eluted with about 30 % acetone as almost pure fractions which were free from 13-dihydrodaunomycin, a major by-product. After extraction with CHCl3, daunomycin powder which was less than 2 % in analog content was obtained with overall recovery yield of about 70 %.