一株产酸性α-淀粉酶产生菌的分离鉴定及所产酶学特性的初步研究

Isolation, Identification and Preliminary Enzymology of an Acidic α-Amylase-producing Fungus

摘要:

从食醋厂内土壤中分离得到一株产酸性α-淀粉酶能力较强的菌株，通过形态学和ITS区基因序列分析的手段对其进行鉴定，对其生长温度及发酵液初始pH值等生物学特性进行分析，并对其所产酶的特性进行研究，研究结果表明：通过形态学及分子生物学鉴定为黑曲霉，并命名为Aspergillus niger ZTL；菌株最适生长温度为35 ℃；最适产酶温度为40 ℃；最适生长pH值为6.0，最适产酶pH值为5.0；所产α-淀粉酶在pH值4.5~7.0时酶活性保持在80%以上；该酶的最适作用温度范围是40~50 ℃；通过测定该酶的热稳定性表明，在40~50 ℃时酶较稳定，但在60 ℃时保温一段时间后，酶稳定性显著下降；Ca2+对该酶有一定的激活作用，Na+对该酶的活性作用不明显，而Mg2+、Fe2+和Cu2+对酶的活性均有比较明显的抑制作用；该酶的Km值为4.52×10-3g/L。从而确定该菌株所产的α-淀粉酶具有具有很大的开发价值。

Abstract:

An acidic α-amylase-producing fungal strain was isolated from the soil near a vinegar factory and was identified by morphology and ITS sequence analysis. Growth characteristics such as growth temperature and pH of the initial fermentation solution as well as the characteristics of the enzyme produced by this strain were examined. The strain was identified as Aspergillus niger and was named Aspergillus niger ZTL. The optimal growth and enzyme-producing temperatures were determined as 35 ℃ and 40 ℃, respectively, while optimum growth and enzyme-producing pH values were 6.0 and 5.0, respectively. The activity of α-amylase produced was above 80% within the pH range of 4.5 to 7.0. The optimum functional temperature range was between 40 ℃ and 50℃, and the enzyme was stable within this range, as determined by thermal stability analysis. Additionally, the enzyme stability decreased significantly when kept at 60 ℃ for some time. The enzyme was activated by Ca2+ to some extent and inhibited by Mg2+, Fe2+, and Cu2+, while Na+ showed no obvious effect. The Km value was 4.5×10-3 g/L. These results indicate that α-amylase produced by the strain isolated in this study has potential development value.