产甲壳素酶多粘类芽孢杆菌A1的筛选鉴定及发酵产酶条件研究

Screening of a strain of chitinase producing Paenibacillus polymyxa A1 and investigation on its fermentation conditions for chitinase production

从土壤中分离得到一株产甲壳素酶的细菌,经形态学、生理生化及分子生物学鉴定,确定为多粘类芽孢杆菌,命名为A1。研究发现甲壳素、壳聚糖和淀粉可诱导该菌产甲壳素酶;添加尿素可提高甲壳素酶产量。本文研究确定该菌发酵产酶条件如下:培养基采用1%甲壳素(120目),0.05%Mg SO_4·7H_2O,1.2%尿素,0.5%Na Cl,0.07%K_2HPO_4,0.03%KH_2PO_4,0.3%酵母提取粉,初始p H4.5,接种龄12 h,接种量1%,于37℃培养78 h,在此条件下,该菌产甲壳素酶水平达到0.549 U/m L。该菌在对数期,其产酶曲线的上升略滞后于生长曲线变化;而在衰亡期,产酶曲线的降低略早于生长曲线的降低,说明该酶的mRNA的稳定性较差。

A strain of chitinase producing bacteria was isolated from soil, and was identified to be Paenibacillus polymyxa based on its morphological, physiological and biochemical characteristics and I6S rDNA sequencing. The strain was named as Al.Chitin,chitosan and starch can induce A] to produce chitinase.The adding of urea in medium improved the production of chitinase.The fermentation conditions for chitinase production were determined as follows：the fermentation medium consisting of 1% chitin（ 120 mesh）,0.05% MgSQ-7H2O, 1.2% CO（ NH2）2, 0.5% NaCI,O.03% KH2PO4 ,0.07% K2HPO4,0.3% yeast extract powder, pH4.5,starter culture age 12 h, inoculum size 1% ,fermenting at 37℃ for 78 h. Under such conditions, the chitinase activity achieved 0.549 U/mL. At the exponential phase,the rising of chitinase production curve slightly lagged behind the growth curve of A1, at the decline phase,the falling of chitinase production curve was slightly earlier than the falling of growth curve.The results indicated that the mRNA of the chitinase was unstable.