响应面法优化海洋细菌NTa产琼胶酶的发酵条件

利用Plackett-Burman试验、最陡爬坡试验和响应面法，对培养基组成、培养条件对Stenotrophomonas sp .NTa发酵产琼胶酶的影响进行分析并优化，研究该菌株发酵产酶的动态规律，并利用薄层色谱和MALDI-TO-MS进行酶解产物的鉴定。结果显示，在琼脂、酵母浸膏、CaCl2、MgSO4·7H2O、培养基的初始pH值、装液量、接种量几个因素中，酵母浸膏和培养基初始pH值对菌株NTa产琼胶酶具有显著影响，在含有1.03%酵母浸膏、初始pH=8.0的基础发酵培养基（NaCl、KNO3、MgSO4·7H2O、CaCl2、K2HPO4、FeSO4·7H2O、琼脂的质量浓度分别为50，5.0，5.0，0.2，0.1，0.02，2.0 g/L）中可获得最高的琼脂酶活力。菌株在28 ℃、180 r/min条件下发酵时，对数生长中后期快速合成琼胶酶。发酵48 h，琼胶酶活力高达2.688 U/mL。酶解72 h的产物分析结果显示，菌株NTa琼胶酶水解琼脂主要产生四糖。

Response Surface Optimization of Fermentation Conditions for Agarase Production by Marine Bacterium NTa

Effects of medium composition and culture conditions on agarase production by Stenotrophomonas sp.NTa in liquid culture were investigated by Plackett-Burman design,steepest ascent method and response surface methodology.The dynamic law of enzyme production by this strain was studied,and the enzyme hydrolytic products were analyzed by thin layer chromatography and MALDI-TOF-MS.Among the tested seven factors,including agar,yeast extract, MgSO4·7H2O, CaCl2,initial culture pH,liquid medium volume,and inoculum size,yeast extract and initial culture pH had significant effects on agarase production.The highest agarase production was obtained in the basic fermentation medium（NaCl 50.0 g/L,KNO3 5.0 g/L,MgSO4·7H2O 5.0 g/L,CaCl2 0.2 g/L,K2HPO4 0.1 g/L,FeSO4·7H2O 0.02 g/L,agar 2.0 g/L) containing 1.03% yeast extract and with initial pH of 8.0.At the conditions of 25 ℃ and 180 r/min,agarase was rapidly synthesized in the middle and late log phase during the fermentation.After incubation for 48 h,the agarase activity reached 2.688 U/mL.Analysis of the enzyme hydrolytic products after 72 h reaction showed that the hydrolysis of agar by strain NTa agarase mainly produced tetraose.