褐藻胶裂解酶产生菌的分离鉴定及产酶发酵优化

Identification of an Alginate Lyase Producing Strain Halomonas sp.WF6 and Fermentation Optimization

对一株从腐烂海带中筛选得到的产褐藻胶裂解酶的菌株进行鉴定,并对其产酶条件进行发酵优化。经形态学、生理生化特征和分子生物学鉴定,将其鉴定为盐单胞菌属,并命名为Halomonas sp.WF6。通过在摇瓶培养水平上进行单因素和多因素正交试验,确定褐藻胶裂解酶产生菌WF6的最适产酶培养基为:褐藻酸钠6.0g/L,蛋白胨5.0g/L,酵母粉2.5g/L,NaCl30g/L,K^+5 mmol/L。进而采用最适培养基进行产酶条件的优化,优化后的发酵产酶条件为:初始pH8.0,培养温度25℃,接种量为2%,摇瓶装液量30 ml/250 ml,培养时间39 h。优化后的褐藻胶裂解酶酶活达117.66 U/ml,是优化前的2.1倍。该酶对褐藻酸钠的酶解产物主要由聚合度为二和三的褐藻寡糖组成。

An efficient alginate-degrading strain isolated from rotten seaweed was identified. With the results of morphological properties, physiological characteristics as well as 16S rDNA sequencing, the strain was identified as Halomonas sp. WF6. The fermentation medium component was optimized by both single factor and orthogonal test, which was composed of sodium alginate 6.0 g/L, peptone 5.0 g/L, yeast extract 2.5 g/L, NaC1 30 g/L, K＋ 5 mmol/L. This strain was cultivated at 25℃ for 39 h with optimized conditions of initial pH 8.0, inoculum size 2% and liquid volume 30 mL/250 ml, the alginate lyase activity was increased to 117.66 U/ml, which was 2.1-fold compared with the control. The enzymatic hydrolysates of sodium alginate mainly included di- and tri-alginate oligosaeeharides.