利用米酒廠發液進行檸檬酸醱酵

Abstract

米酒廠蒸餾廢液可被Aspergillus foetidus (F-0213）用做檸檬酸醱酵的培養基。由於廢液中含糖量低，所以必須添加適當的碳源。本實驗選擇蔗糖做為碳瞟。磷酸鹽的添加對菌絲的生長只有少許的影響，但會使檸檬酸的產量降低很多。添加4%甲醇或0.05%彩黃血鹽，很明顯的會提高檸檬酸的產量。微量元素鎂的添加，不但不會提高檸檬酸的產量且與鎂同時添加時，反而有抑制的作用。氮源的添加，可以增加菌絲的生長及糖的消耗，而唯有添加少量（0.2%）的硝酸鈉或尿素，可提高檸檬酸的產量。廢液的pH值如調高到pH 4.0，可以產生檸檬酸達消耗糖之73.59%，除了不添加氮源外，在6%彩糖濃度下總合上述有利的條件，於28℃靜置培養，接種2.4 ml/100 ml之孢子懸浮液，可使培養液之BOD降低81.55%，其產酸達消耗糖之80.29%；對原料糖收率為78.15%。

The distilled residue of rice liquor was used as a fermentation medium for the production of citric acidl by Aspigillus foetidus (F-0213). since the sugar content in the distilled residue was 10w，the addition of sucrose as a carbon source for the fermentation is needed. The addition of phosphate (KH2PO4) appearod to have little effect on mycelial growth, but markedly reduced the formation of citric acid. Methanol at a concentration of 4% or potassium ferrocyanide at 0.05% can increase the amount of citric acid markedly. The element magnesium could stimulate the production of citrate, however, the addition of zinc element not only had no effect on citrate formation, but cancelled out the stimulation effect caused by magnesium when elements zinc and magnesium added together. The addition of nitrogen compound increased mycelial growth and the consumption of sugar, but only small amount (0.2%） of NaNO3 or urea added could increase the amount of citrate produced. The pH of fermentation medium adjusted to pH 4.0 could produce the citric acid at yield of 73.59% based on the sugar consumed. when the spores were inoculated at a concentration of 2.4 ml/100 ml in the distilled residue with the addition of 0.25g/1 M(subscript g)SO4•7H2O, 4% methanol, 0.05% Ferrocyanide and 6% sucrose at pH 4.0, the yield of citric acid could reach to 80.29% based on the sugar consumption and 78.15% on the sugar addition. After the citric acid fermentation, the BOD of distilled residue could reduce 81,55%．