甘露聚糖酶产生菌F1-5的鉴定及发酵条件研究

Identification of A Mannanase-producing Bacterial Strain F1-5 and Optimization of Its Fermentation Conditions

本研究从实验室保藏高效分泌能降解异甘露聚糖的甘露聚糖酶的细菌F1-5出发,采用菌株的个体和群体的形态观察、生理生化实验及16SrDNA系统发育分析手段进行鉴定,最终确定菌株F1-5为枯草芽孢杆菌(Bacillus subtilis)。Genbank注册号为FJ392725。通过单因素试验和正交优化试验,确定枯草芽孢杆菌F1-5的最佳发酵产酶条件。酵母细胞壁碳源浓度为4.8%,氮源浓度为0.5%,培养基初始pH6.0,接种量为6%,装液量为60ml/250ml三角瓶,转速为180r/min,培养温度为35℃,在此发酵条件下发酵48h,枯草芽孢杆菌F1-5产生的甘露聚糖酶活力达330U/ml,是优化前的3.4倍。发酵罐扩大实验,甘露聚糖酶活力可达582U/ml。

A mannanase-producing bacterial strain F1-5 that isolated and preserved in our laboratory was identified as Bacillus subtilis （Genebank accession number FJ392725） according to the results of morphological observations, physiological and biochemical tests and 16S rDNA sequence homology analysis. The optimal fermentation conditions of F1-5 for producing mannanase were determined to be fermentation for 48 h at 35 ℃ with an inoculation size of 6% in a 250 ml flask with a shaking speed of 180 r/min containing 60 ml of culture medium consisting of 4.8% yeast cell wall as carbon source and 0.5% NH4NO3 as nitrogen source by one-factor-at-a-time and orthogonal array design methods. Under such conditions, the mannanase activity was up to 330 U/ml, which was 3.4 times higher than before the optimization. Furthermore, our 5 L fermentor experiments gave a mannanase activity as high as 582 U/ml. Therefore, these optimal conditions are reliable.