高产柠檬酸黑曲霉菌株的航天诱变选育及其产酸条件的研究

Breeding of high citric acid-producing Aspergillus niger strain by aerospace mutagenesis and its optimization of ferm entation conditions

对在工业生产中有较高性价比的产柠檬酸黑曲霉C9为出发菌株,航天诱变后,进行了透明圈初筛、耐酸度复筛、遗传稳定性和产柠檬酸发酵条件实验。结果表明,选育出的黑曲霉AM-51是一株优良的高产柠檬酸菌株。该菌株的耐酸度能达到16%以上,产酸稳定性良好;以玉米粉为原料,在产酸温度为34℃～37℃、初始pH值为5.5～6.5、发酵时间为70h～96h的条件下产酸率基本稳定。当发酵温度为37℃、初始pH值为6.0、发酵时间为84h时,平均产酸率达16.50%,较出发菌株产酸率(12.80%)提高了22.42%。

Aspergillus niger C9 was used as the original strain mutated by aerospace mutagenesis.One mutated strain（A.niger AM-51） producing high citric acid was obtained after transparent circle preliminary screening,acid resistance,genetic stability and fermentation conditions optimization.The results showed that the strain can tolerate over 16% acid,and the production citric acid stability was well.The optimal fermentation conditions were as followed： fermentation temperature 34℃～37℃,initial pH value 5.5～6.5 and fermentation time 70h～96h,When fermentation temperature was 37℃ and initial pH value was 6.0,the average yield of acid reached 16.50% using corn flour as raw material after fermented for 84h,which was about 12.80% higher than that of the original strain.