4株琼胶降解菌的分离、鉴定及产酶条件分析

摘要

Four Gram negative strains of agarase-producing bacteria HD, JL, QJ and HS were isolated from algaes and intestine of sea cucumber. The optimum growth conditions for enzyme production were determined as follows:2216E marine medium, initial pH 7.5, 0.30%agar, culture temperature 28℃ with 120 rpm shaking and culture time 36 hours. The high enzymic activities were detected in the extracellular products of bacteria. Physiological and biochemical identification together with phylogenetic analysis based on 16S rDNA sequence similarity showed that HD, JL and HS belong to Agarivorans albus. QJ was related with Simiduia sp., Saccharophagus sp. and Teredinibacter sp., but its biochemical traits were different from those of these related species. Sequence ofβ-agarase gene was cloned from HD, JL and HS and they were highly related with those from other bacterial species.%　　从海藻及海参中分离筛选得到4株琼胶降解菌HD、JL、QJ和HS,均为革兰氏阴性菌,确定了它们发酵产酶的最佳条件均为：2216E海水培养基、初始 Ph 7.5、琼胶底物浓度0.30%、培养温度28℃、培养时间36 h。大部分酶分泌到细菌细胞外。生理生化检测、16SrDNA序列同源性及聚类分析结果表明, HD、JL、HS为白色噬琼胶菌(Agarivorans albus)；QJ的16SrDNA序列与Simiduia sp.,糖噬胞菌属( Saccharophagus sp.)和船蛆杆菌(Teredinibacter sp.)的相似性为93%~94%,在进化树上单独形成一个分支,但生理生化特征与它们有所不同,分类地位需要进一步确定。从HD、JL和HS中能克隆到β-琼胶酶基因,它们与其他物种的β-琼胶酶基因序列的相似性为97%~98%。