【摘要】 为筛选高效产褐藻胶裂解酶菌株,以褐藻胶作为唯一碳源,在海星Asteroidea sp.内脏中筛选出一株产胞外褐藻胶裂解酶的菌株AlgX2,并进行了菌株鉴定、产酶条件优化及降解寡糖结构分析。结果表明:经过菌株形态、生理生化及16S rRNA基因鉴定,该菌株属于盐单胞菌属,命名为Cobetia AlgX2;以3,5-二硝基水杨酸法(DNS)测定的菌株酶活性为指标,对褐藻胶裂解酶菌株产酶活性进行正交试验显示,产褐藻胶裂解酶的菌株最适产酶培养基成分为褐藻胶14 g/L、硫酸铵4 g/L、NaCl 30 g/L、初始pH 6.0,优化产酶培养条件为培养温度22℃、接种量2%、装液量50 mL/250 mL、转速150 r/min;在最优产酶培养条件下进行10 L发酵罐产酶试验显示,发酵液酶活力最高为0.176 U/mL;利用粗酶液酶解制备褐藻胶寡糖,并对寡糖进行HPLC色谱检测显示,样品的聚合度为dp2～dp5。研究表明,Cobetia AlgX2菌株可用于扩大发酵生产,产酶效率高且褐藻胶裂解效果显著。更多还原

【Abstract】 A alginate-producing lyase bacterial strain AlgX2 was selected in the viscera of starfish Asteroidea sp. using sodium alginate as sole carbon source in order to screen biodegradable alginate lyase microbial strain which was identified to belong to the genus of Cobetia, named as Cobetia AlgX2, upon on the identification of strain morphology, physiology, biochemistry and 16 S rRNA gene. The enzyme activity of the strain determined by the DNS method was used as an indicator, and the culture medium and conditions of the stain were optimized by orthogonal experiment. The results showed that the optimum enzyme-producing medium for the stain was observed under conditions of 14 g/L of alginate, 4 g/L of ammonium sulfate, 30 g/L of NaCl, initial pH of 6.0, culture temperature of 22 ℃, inoculation volume of 2%, liquid volume of 50 mL/250 mL and speed of 150 r/min. Under the optimal conditions, an enlarged volume of 10 L fermentation was applied in culturing and producing the enzyme, with the enzyme activity of 0.176 U/mL. HPLC analysis of alginate oligosaccharides prepared by enzymatic hydrolysis of crude enzyme liquid revealed that the samples had the polymerization degree of dp2-dp5. The findings indicate that this strain can be used to expand fermentation production, high enzyme yielding efficiency and significant alginate cracking effect.更多还原