Aspergillus niger CU-1菌株在水相中深层发酵生产高含量异麦芽低聚糖的研究

Produce Isomaltooligosaccharides with High Concentration by Submerged Fermentation of Aspergillus niger CU-1

对实验室选育的Aspergillus niger CU-1菌株在最佳培养条件下菌体生长与产酶的关系进行测定,在最佳培养条件下,72h生物量达到最大值,88h左右α-葡萄糖转苷酶活力达到最高点,溶液pH5.0有利于α-葡萄糖转苷酶稳定积累;将A.niger CU-1按照10%接种量接入25%木薯淀粉和3%麸皮的转苷反应培养基中,在30℃、160r/min下培养3.0d,定时取样检测pH、还原糖、总糖、菌体干重、异麦芽低聚糖(IMO)含量,绘制发酵过程曲线。产物经过HPLC分析,表明主要的有效组分是异麦芽糖、潘糖、异麦芽三糖和异麦芽四糖,还有明显的聚合度为5和6的低聚糖,异麦芽低聚糖含量≥80%,葡萄糖含量约4%。结果表明,高浓度底物和长时间发酵策略,适合于Aspergillus niger CU-1的发酵生产高含量异麦芽低聚糖。

In this paper, Aspergillus niger CU-1 was found to produce maximum amount of α-glucosidase at 88 h while to peak its biomass at 72 h under the best conditions. The pH value of 5.0 was helpful to pile up α-glucosidase. The inoculum of A. niger CU-1 was 10% in a medium contained 25% （w/v） of cassava starch and 3% （w/v） of wheat bran. Then transglucosylation performed for 3.0 d at 160 r/rain and 30℃. The pH, reduced sugar, total sugar, biomass （dry weight） , and isomahooligosaccharides （IMOs） were tested. HPLC analysis showed the amount of effective IMOs was higher than 80% , including isomaltose, panose, isomaltotriose, isomahotetraose, and oligosaccharides with polymerization of 5 or 6. The glucose was about 4%. These results showed that a long period of fermentation with high concentration of substrate was suitable for producing IMOs by A. niger CU-1.