低温β-半乳糖苷酶产生菌的筛选、鉴定、生长特性及酶学性质的初步研究

SCREENING AND IDENTIFICATION OF COLD-ACTIVE β-GALACTOSIDASE-PRODUCING BACTERIUM AND CHARACTERIZATION OF THE β-GALACTOSIDASE

自北冰洋楚科奇海、加拿大海盆、格陵兰海和中国南极中山站近岸的海水、海冰和沉积物样品中分离的322株低温细菌中筛选出73株低温β-半乳糖苷酶产生菌,并对其中1株BCw006进行了研究。通过16S rDNA序列同源性分析表明,该菌株属于交替单胞菌属,定名为Alteromonas sp.BCw006。对该菌株研究表明:该菌最适生长和产酶温度为24℃;在pH6.0—8.0、含0%—6.O% NaCl的培养基条件下菌株能够较好地生长与产酶,其最适生长和产酶NaCl浓度分别为3%和1%,乳糖对β-半乳糖苷酶合成具有明显诱导作用,酵母粉和蛋白胨是菌株生长和产酶较适宜的氮源,酶的最适作用温度为35℃,0℃时能保持35℃下酶活的25%左右,表明其具有较好的适应低温特性。酶对热敏感,60℃时作用30min后酶活力下降了41%。

In this study, 73 β-galactosidase-producing bacterial strains were screened from 322 cold- adopted isolates from the seawater, sea ice and marine sediment samples collected from Chuk- chi Sea, Canada Basin, Greenland Sea and coastal regions of Chinese Antarctic Zhongshan Station. Strain Bcw006, one of the producers, was further studied. Based on 16S rRNA gene sequence homology, the strain was identified as Alteromonas sp. BCw006. The optimal growth and enzyme production for the strain was at 24℃, pH of 6.0--8. 0 ; The optimal NaCl concentration for growth and enzyme production was 3 % and 1%, respectively. The production of β- galactosidase of strain BCw006 was effectively induced by lactose. Yeast extract and peptone were good nitrogen source for enzyme production. The enzyme was cold active（ optimal activity at35 ℃ and 25% activity remaining at 0 ℃） and heat labile（all% lost at 60 ℃ after 30 rain）.