【摘要】 从堆肥中筛选到一株产耐热内切葡聚糖酶的放线菌菌株,通过形态观察和16S rRNA序列分析,鉴定为蚀木链霉菌(Streptomyces Xylophagus)。实验中对其产酶的液态发酵条件进行了研究,碳源为1%(w/v)羧甲基纤维素钠,氮源为1%(w/v)豆粕粉,250ml三角瓶30%装液量,接种量为2%,培养基初始pH为8.0,培养温度为40℃,200r/min培养48h后,发酵液中内切葡聚糖酶活达到0.538IU/ml。该酶的最适作用温度和pH分别为50℃和7.0,50℃下酶活保持1h不变,60℃保温1h,仍有60%的原酶活性,pH为6.0～7.0酶活稳定,该酶属于一种耐热的中性内切葡聚糖酶。更多还原

【Abstract】 A strain KX6,producing thermotolerant endoglucanase,was isolated from compost. The morpholo-gical identification and 16S rRNA sequence analysis showed it belongs to Streptomyces xylophagus. The production and characterization of endoglucanase from Streptomyces xylophagus KX6 was studied. Maximum endoglucanase yield of 0.538 IU/ml was achieved with medium pH8.0,containing CMC2Na 1.0% as carbon resource,soybean meal 1% as nitrogen resource,2% inoculating volume,30% 250 ml triangle flask bulk for medium volume at 40℃ 200r/min shaker for 48h. The endoglucanase exhibited optimum catalytic activity at pH7.0 and 50℃. The enzyme was stable at 50℃,and able to retain 60% of the full activity,when it was incubated at 60℃ for 1h.The enzyme was stable at pH6.0~7.0. All these findings suggest that the enzyme is a thermotolerant neutral endoglucanase.更多还原