1株褐藻胶降解菌的筛选、鉴定及产酶条件优化

Screening and Identification of an Alginate Degrading Strain and Optimization of Its Enzyme Producing Conditions

为获得可产生褐藻胶裂解酶并高效降解褐藻胶的菌株,以海藻酸钠为唯一碳源配制培养基,以透明圈法进行初筛,DNS法复筛,从海洋生物中筛选得到1株高酶活力褐藻胶降解菌株B12,经16S rDNA序列分析、生理生化试验、电镜观察,确定该菌为弧菌属(Vibrio sp.)。通过单因素试验及响应面优化试验对影响菌株生长和产酶条件的5个因素(发酵初始pH值、发酵温度、NaCl质量浓度、接种量和装液量)进行优化。得到该菌株最佳产酶条件:pH 6.52,发酵温度28.2℃,NaCl质量浓度20.1 g/L,接种量2.1%,装液量59.5 mL。在最佳发酵条件下,B12菌株酶活力可达91.68 U/mL,相比于优化前提高了38.5%。菌株开始产酶时间提前6 h,4℃冷藏酶活力稳定性较好。

In order to obtain a strain that can produce alginate lyase and degrade alginate efficiently,sodium alginate was used as the sole carbon source to prepare culture medium.An alginate degradable strain B12 with high enzyme activity was screened from marine organisms by transparent circle method and DNS method to rescreen.The strain was identified as Vibrio sp.through 16S rDNA sequence analysis,physiological and biochemical tests and electron microscope observation.By single factor test and response surface optimization experiment,five factors affecting the growth and enzyme production conditions of the strain,initial pH value,fermentation temperature,NaCl concentration,inoculum and liquid filling volume were optimized.The optimum conditions for enzyme production were as follows:pH 6.52,28.2℃,NaCl concentration 20.1 g/L,inoculation amount 2.1%,and liquid filling volume 59.5 mL.Under these optimal fermentation conditions,the enzyme activity of strain B12 reached as high as 91.68 U/mL,increased by 38.5%higher than that before optimized one.The enzyme start producing time of the strain was advanced by 6 hours,and the enzyme activity has good stability when keep in 4℃cold storage.