Liu Juanjuan, Cheng Jing, Huang Min, Shen Chen, Xu Ke, Xiao Yazhong, Pan Wenjuan, Fang Zemin
School of Life Sciences, Anhui University, Hefei, China.
Anhui Key Laboratory of Modern Biomanufacturing, Hefei, China.
Front Microbiol. 2021 Apr 8;12:646801. doi: 10.3389/fmicb.2021.646801. eCollection 2021.
The hydrolyzation of raffinose into melibiose by using invertases under mild conditions improves the nutritional value of soybean products. However, this strategy has received little attention because a suitable invertase remains lacking. In this study, a novel invertase named InvDz13 was screened and purified from and characterized. InvDz13 was one of the invertases with the highest specific activity toward raffinose. Specifically, it had a specific activity of 229 U/mg toward raffinose at pH 6.5 and 35°C. InvDz13 retained more than 80% of its maximum activity at pH 5.5-7.5 and 25-40°C and was resistant to or stimulated by most cations that presented in soymilk. In soymilk treated with InvDz13 under mild conditions, melibiose concentration increased from 3.1 ± 0.2 to 6.1 ± 0.1 mM due to raffinose hydrolyzation by InvDz13. Furthermore, the prebiotic property of InvDz13-treated soymilk was investigated via fermentation by human gut microbiota. Results showed that InvDz13 treatment increased the proportion of the beneficial bacteria and by 1.6- and 3.7-fold, respectively. By contrast, the populations of and decreased by 1.8- and 11.7-fold, respectively. Thus, our results proved that the enzymatic hydrolysis of raffinose in soymilk with InvDz13 was practicable and might be an alternative approach to improving the nutritional value of soymilk.
在温和条件下利用转化酶将棉子糖水解为蜜二糖可提高大豆制品的营养价值。然而，由于仍缺乏合适的转化酶，该策略很少受到关注。在本研究中，从[具体来源未给出]筛选并纯化了一种名为InvDz13的新型转化酶，并对其进行了表征。InvDz13是对棉子糖具有最高比活性的转化酶之一。具体而言，在pH 6.5和35°C条件下，它对棉子糖的比活性为229 U/mg。InvDz13在pH 5.5 - 7.5和25 - 40°C时保留了超过80%的最大活性，并且对豆浆中存在的大多数阳离子具有抗性或受到其刺激。在温和条件下用InvDz13处理的豆浆中，由于InvDz13对棉子糖的水解作用，蜜二糖浓度从3.1±0.2 mM增加到6.1±0.1 mM。此外，通过人体肠道微生物群发酵研究了经InvDz13处理的豆浆的益生元特性。结果表明，InvDz13处理使有益细菌[具体细菌名称未给出1]和[具体细菌名称未给出2]的比例分别增加了1.6倍和3.7倍。相比之下，[具体细菌名称未给出3]和[具体细菌名称未给出4]的数量分别减少了1.8倍和11.7倍。因此，我们的结果证明了用InvDz13对豆浆中的棉子糖进行酶水解是可行的，并且可能是提高豆浆营养价值的一种替代方法。
