产淀粉酶芽孢杆菌的分离鉴定、高温驯化及酶学性质研究

Isolation,identification,high temperature acclimation and enzymatic property of amylase-producing Bacillus

该研究从酱香型高温大曲中筛选出产淀粉酶芽孢杆菌,对筛选菌株进行形态学观察、分子生物学鉴定以及高温驯化,并针对驯化前后所产淀粉酶进行酶学性质研究。结果表明,分离筛选到的产淀粉酶菌株AmyZ5为贝莱斯芽孢杆菌(Bacillus velezensis),在45℃培养条件下生物量及淀粉酶活性有较大幅度降低。菌株AmyZ5经高温驯化,生长温度提高至45℃,并缩短对高温环境的适应期,培养3 h时OD600 nm值即提高4.2倍。高温驯化后的菌株HTAmyZ5所产淀粉酶的最适反应温度从40℃提高至70℃,最适反应pH仍为3,在20~90℃及pH 1~7条件下酶活均能保持在60%以上,pH 9时仍有40%的酶活;最高酶活性提高了3.1倍,达到322.1 U/mL;但稳定性受到高温环境影响略有下降。该研究对酱香型大曲微生物高温发酵、原料高效持久利用及关键香气成分的形成均具有一定的参考意义。

Amylase-producing strains were selected from sauce-flavor(Jiangxiangxing)high-temperature Daqu.Morphological observation,molecular biological identification and high temperature acclimatization of the screened strains were carried out,and the enzymatic properties of amylase produced before and after acclimation were studied.The results showed that the isolated amylase-producing strain AmyZ5 was identified as Bacillus velezensis.The biomass and amylase activity decreased significantly at 45℃.After high temperature acclimatization,the growth temperature of strain AmyZ5 was increased to 45℃,the adaptation period to high temperature environment was shortened,and the OD600 nm value increased 4.2 times after culture for 3 h.The optimum reaction temperature of amylase produced by the strain HTAmyZ5(after high temperature acclimation of strain AmyZ5)increased from 40℃to 70℃,the optimum reaction pH was still 3,the enzyme activity could be maintained above 60%at 20-90℃and pH 1-7,and the enzyme activity was still 40%at pH 9.The highest activity increased 3.1 times to 322.1 U/ml.However,the stability slightly decreased under the influence of high temperature environment.This study had certain reference significance for the high-temperature fermentation of sauce-flavor Daqu,efficient and sustainable utilization of raw materials and the formation of key aroma components.