METHOD OF PREPARING CITRIC ACID

摘要

Citric acid is prepd. by growing a new Aspergillus niger R-1 strain, (I), on a nutrient medium contg. sources for C, N and mineral salts, followed by mycelium sepn. and extn. of end-prod. from culture liquor. (I) is produced by combining activity of UV-radiation, ethylene imine and N-nitrosomethyl urea on Aspergillus niger EU-119 (II). Citric acid is used esp. in pharmaceutical and food industry. (i) Cultivation of (I) in place of (II) increases citric acid yield from 88-89wt.% to 99wt.%, w.r.t. sugar consumed, and, on molasses media, citric acid formation is increased from 93-94% to 97-98%, w.r.t. acid sum. (ii) (I) resists antagonistic bacteria, inhibits formation of gas-, acid- and nitrite-forming bacteria in fermentation process and ferments molasses well. (iii) (I) is less sensitive to chemical compsn. of starting molasses, and allows use of a lower quality molasses.