L-苹果酸产生菌F-871变株合成延胡索酸酶的研究*

温特曲霉AspergilluswentiiF-871是高效转化延胡索酸为L-苹果酸的变株,通过对其合成延胡索酸酶的因素进行研究,筛选了培养基主要营养元素有L-精氨酸、酪氨酸、丝氨酸、天冬氨酸、苏氨酸、赖氨酸及相应含量丰富的酵母粉、黄豆饼粉和玉米浆。该变株生长阶段条件为:pH6.0,温度2830℃,培养时间为24h,酶合成阶段最适条件:接种量15%,初始pH6.8,培养温度2830℃,装量8090ml/500ml,酶合成周期40h。在优化的培养条件下,F-871变株延胡索酸酶合成水平可达156.33u/g,100ml发酵液中的酶可将延胡索酸转化为L-苹果酸32.06g,比国内一步发酵法产酸88.5%提高约4倍,转化率由85%提高到106.87%,发酵周期由90h缩短至57h。

STUDIES ON SYNTHESIS OF FUMARASE BY MUTANT ASPERGILLUS WENTII F-871

The factors of synthesis the fumarase by mutant Apergillus wentii F-871 that could convert fumaric acid into L-malate efficiently were studied. The culture medium containing yeast meal, defatted soybean meal and maize extract, which enriched in L-arginine, tryptophan, serine, aspartic acid, threonine and lysine, was screened. The optimal growth condition was observed after incubation 24 h, at pH 6.0, and at temperature of 28C to 30C. The optimal fumarase synthesis condition was observed after shaking incubate 40 h with an inoculum of 15%, initial pH 6.8 to 7.0, temperature of 28 to 30C, and medium volume of 80 to 90 ml per 500 ml flask. Under the above condition, the fumarase activity reached to 156.33 u/gcell, and the fumarase per 100 ml fermentation can produce 32.06 g L-malate from fumeric acid. The production of L-malate in the present process was 4 times that of one phase method of fermentation, the rate of conversion was increase to 106.87% from 85%, and fermentation period was shortened to 57 h from 90 h.