从云南温泉中分离鉴定了3株产异淀粉酶的芽孢杆菌,经16SrDNA序列比对分析及主要生理生化研究,初步鉴定为:Bacillus amyloliquefacieLCEP-1、Bacillus subtilisDL-3-4-2、Bacillus subtilisDMJS-2-1。GeneBank登录号分别为:gb.GQ199589、gb.GQ199593、gb.GQ199594。3株菌所产的异淀粉酶都能降解玉米支链淀粉。酶解反应的最适pH分别为pH6.8、5.4和pH7.8;最适温度分别为60、55、60℃。优化条件下,最高酶活分别为:36.5、18.89、11.08μ/mL。3株菌的酶对不同金属离子有不同的反应,金属螯合剂EDTA对酶活又有较强的抑制作用,推测可能都属于金属酶。3株菌能在偏酸性至中性的pH范围内(pH4.4~8.0)保持稳定,可以在pH变化较大的条件下保持较高的酶活,在偏酸性、中性和弱碱性环境中都能有效地水解淀粉质底物。3株菌所产异淀粉酶,底物专一性强,最适pH可低至5.4。

To determine the physiological and biochemical characteristics,three Bbacillus strains were isolated from Yunnan springs and were identified by 16 SrDNA sequence analysis as Bacillus amyloliquefacie LCEP-1,Bacillus subtilis DL-3-4-2 and Bacillus subtilis DMJS-2-1 with their GeneBank accession numbers of gb.GQ199589,gb.GQ199593 and gb.GQ199594,respectively.Isoamylases from all three strains could hydrolyze corn amylopectin.The optimal pH of enzymatic reaction respectively was 6.8,5.4 and 7.8;optimum temperature was 60℃,55℃ and 60℃.Under optimized conditions,the highest enzyme activity was 36.5 U/mL,18.89 U/mL and 11.08 U/mL.The enzymes react differently to metal ions.It is proposed that the three isoamylases belong to metal enzymes because some metal and EDTA showed stronger inhibitory effect than others on the enzyme activity.Within the pH range of 4.4~8.0 all three enzymes remain stable;the enzyme activities can maintain high under the condition of weak acidic,neutral to weak alkaline.