1株产菊粉酶菌株的筛选、鉴定及发酵条件优化

Isolation,Identification & Ferment Condition Optimization of an Inulinase-Producing Strain

筛选分离可以分解菊芋中菊糖的菌株。采用平板稀释法从土样中筛选出能够分解菊芋中菊糖的菌株,并从中得到1株酶活较高的真菌A-15,经菌落观察及采用18S rRNA基因测序鉴定,研究不同因素对菌株菊粉酶活力的影响。通过对分离得到的菌株形态观察及分子鉴定后,确定菌株A-15为黑曲霉(Aspergillus niger)。通过正交试验优化菌株A-15的发酵条件分析结果显示,菌株A-15产菊粉酶最优条件:最佳氮源为酵母膏,氮源量1.0%,氯化钠0.5%,磷酸氢二钾0.3%,菊芋汁定容,初始pH 6,培养温度30℃,摇瓶发酵6 d。结果表明菌株A-15具有很好地降解菊芋中菊糖的性能。

The inulinase production strains that could decompose inulin from Jerusalem artichoke（ Helianthus tuberosus） were screened. Plate dilution method was used to screen strains from soil samples that could decompose inulin from H. tuberosus. A fungal strain A-15 with fairly high enzyme activity was obtained and classified as Aspergillus niger after identifying the morphological,physiological and biochemical properties and 18 S rRNA gene sequencing,and studied the influence of different factors on the inulinase activity. The optimization of the fermentation conditions for A-15 strain through orthogonal experiments were： The best nitrogen source was yeast extract with nitrogen amount at 1. 0%（ W/V）,0. 3% Na Cl,and 0. 3% K_2HPO_4,constant volume of Jerusalem artichoke juice,initial pH 6,culture temperature 30 ℃ and shaking fermenting time for 6 days. Strains A-15 has good performance in the degradation of Jerusalem artichoke inulin.