一株产高活性多酚氧化酶菌株筛选鉴定及其酶学性质

采用变色圈法从土壤样品中分离筛选产多酚氧化酶的菌株，对其进行形态学观察、分子生物学鉴定，并对其所产多酚氧化酶的酶学性质进行研究。结果表明，筛选得到1株产多酚氧化酶活性较高的菌株，命名为ZL-2，其被鉴定为竹黄菌属（Shiraia sp.）。菌株ZL-2发酵8 d产多酚氧化酶酶活最高，达到521 U/mL。菌株ZL-2产多酚氧化酶最适底物为邻苯二酚，其最适pH值为6、最适温度为30 ℃；酶活在温度20～40 ℃及pH 3～6范围内稳定。金属离子Cu2+、Mg2+、Mn2+、Fe3+、Zn2+对多酚氧化酶都有激活作用，其中Cu2+激活作用最强；Ca2+、Al3+对酶活有一定抑制作用；L-抗坏血酸和亚硫酸氢钠对该酶抑制作用较强。

Screening and identification of a strain producing polyphenol oxidase with high activity and its enzymatic properties

Polyphenol oxidase-producing strains were isolated and screened from soil samples by color-changing circle method. Morphological observation and molecular biological identification were carried out, and the enzymatic properties of polyphenol oxidase produced by strains were studied. The results showed that a strain with high polyphenol oxidase activity was obtained, named ZL-2, and identified as Shiraia sp. The polyphenol oxidase activity produced by strain ZL-2 was the highest after fermentation for 8 d, which reached 521 U/ml. The optimum substrate of polyphenol oxidase production by strain ZL-2 was catechol, and the optimum pH and temperature was 6 and 30 ℃, respectively. The enzyme activity was stable at 20-40 ℃ and pH 3-6. The metal ions Cu2+, Mg2+, Mn2+, Fe3+ and Zn2+ could activate the polyphenol oxidase, among them, activation effect of Cu2+ was the strongest. Ca2+ and Al3+ had certain inhibitory effect on the enzyme activity. L-ascorbic acid and sodium bisulfite had stronger inhibitory effects on the enzyme.