嗜碱细菌碱性果胶酶的研究——Ⅰ.菌种筛选、产酶条件和酶作用条件的研究

STUDIES ON ALKALINE PECTINASE FROM ALKALOPHILIC BACTERIA Ⅰ.Selection of Strains and Studies on the Culture Conditions for Enzyme Producing and Enzyme Properties

从碱性土壤中分离得到的97株嗜碱细菌,从中筛选到15个产碱性果胶酶活力较高的菌株,摇瓶发酵酶活力范围1467～2500u·ml^(-1).其中被鉴定为专性嗜碱芽孢杆菌(Bacillussp.)的 HL-6菌株在 pH8～11.5培养基中生长良好,在 pH7以下不生长。该菌产碱性果胶酶的最适培养条件为:以2%果胶和2%乳糖为复合碳源,培养基起始 pH10～10.5,温度37℃,摇瓶培养60h 达产酶高峰。0.5%甘氨酸提高酶活平均达34%。在上述条件下,芽孢杆菌LH-6菌株摇瓶发酵的粗酶液以果胶为底物,酶作用的最适 pH 为11.5,最适温度为60℃。

Fifteen strains producing high activity of alkaline pectinase were selected from the ninety-six alkalophilic bacteria isolated from alkaline soil.The range of the enzyme activity produced by above strains with shalking was 1467-2500 u·ml^(-1). Bacillus sp.LH 6 was determined as a stable obligate alkalophilic and alkline pectinase producing bacteria.This microorganism had good growth in pH 8-11.5 media,and no growth occurred below pH7.The culture conditions for the enzyme production was investigated.The organism was grown in the medium containing complex carbon source(2%(w/v)pectin and 2%(w/v) lactose)at an initial pH of 9.7 and 37℃,and the highest enzyme activity was obtained after 60 h cultivation with shalking.Glycine(0.2—1% w/v)was evidently effective to stimulate the production of the enzyme,and the average rate of increase in the enzyme activity produced by the organism was reached 34% at 0.5%(w/v).The investigation on some properties of the crude enzyme solution produced by Bacillus sp.LH 6 under above culure conditions indicated when the pectin was used as the substrate of the enzymes, the optimum pH and temperature for the enzyme activity was 11.5 and 60℃.