嗜盐菌Haloferax mediterranei R4胞外淀粉酶的研究

HaloferaxmediterraneiR4是从地中海分离得到的一株极端嗜盐古生菌,属于富盐菌属(Haloferax)。该菌在适当条件下可以产胞外淀粉酶,此酶需要高浓度NaCl维持其活性及稳定性,在NaCl浓度为2～5mol·L-1时维持较高活性。在NaCl浓度为3mol·L-1时该酶的最适反应pH为6.0～7.0,最适反应温度为50℃,且最适反应温度与NaCl浓度有一定的相关性。Ca2+对酶反应活性有影响。用KCl代替NaCl,该酶可以保留约50%活性,而用Na2SO4代替NaCl则完全失活。

Properties of Amylase from Haloferax mediterranei R4

Haloferax mediterranei R4, is a halophilic archaebacterium. It is able to produce extracellular α-amylase in a suitable condition. This amylase showed a NaCl requirement for both stability and activity. The enzyme displayed maximal activity at pH 7.0, 2-5mol·L -1 of NaCl and its optimal temperature was in a range from 50℃ to 60℃. Our results implied that the optimal temperature had some relevance with the concentration of NaCl. Meanwhile,Ca 2+ was required for the enzyme activity and the activity was about a half when we added 2 mol·L -1 of KCl ,and was almost none when added 1mol·L -1 of Na 2SO 4.